On 17 August 2017 the Advanced LIGO and Virgo detectors observed the gravitationalwave event GW170817a strong signal from the merger of a binary neutronstar system. Less than two seconds after the merger a ray burst GRB 170817A was detected within a region of the sky consistent with the LIGOVirgoderived location of the gravitationalwave source. This sky region was subsequently observed by optical astronomy facilities resulting in the identification of an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first multimessenger astronomical observation. Such observations enable GW170817 to be used as a standard siren meaning that the absolute distance to the source can be determined directly from the gravitationalwave measurements to measure the Hubble constant. This quantity represents the local expansion rate of the Universe sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitationalwave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements ours does not require the use of a cosmic distance ladder the gravitationalwave analysis can be used to estimate the luminosity distance out to cosmological scales directly without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. This value is consistent with existing measurements while being completely independent of them. Additional standard siren measurements from future gravitationalwave sources will enable the Hubble constant to be constrained to high precision.
['Astrophysics - Cosmology and Nongalactic Astrophysics']
A gravitationalwave standard siren measurement of the Hubble constant
{'A GRAVITATIONAL-WAVE STANDARD SIREN MEASUREMENT OF THE HUBBLE CONSTANT': 'THE LIGO SCIENTIFIC COLLABORATION AND THE VIRGO COLLABORATION, THE 1M2H COLLABORATION, THE DARK ENERGY CAMERA GW-EM COLLABORATION AND THE DES COLLABORATION, THE DLT40 COLLABORATION, THE LAS CUMBRES OBSERVATORY COLLABORATION, THE VINROUGE COLLABORATION, THE MASTER COLLABORATION, et al.', 'ABSTRACT': "The detection of GW170817 (Abbott et al. 2017a) in both gravitational waves and electromagnetic waves heralds the age of gravitational-wave multi-messenger astronomy. On 17 August 2017 the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) (LIGO Scientific Collaboration et al. 2015) and Virgo (Acernese et al. 2015) detectors observed GW170817, a strong signal from the merger of a binary neutron-star system. Less than 2 seconds after the merger, a gamma-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO-Virgo-derived location of the gravitational-wave source (Abbott et al. 2017b; Goldstein et al. 2017; Savchenko et al. 2017). This sky region was subsequently observed by optical astronomy facilities (Abbott et al. 2017c), resulting in the identification of an optical transient signal within ∼ 10 arcsec of the galaxy NGC 4993 (Coulter et al. 2017; Soares-Santos et al. 2017; Valenti et al. 2017; Arcavi et al. 2017; Tanvir et al. 2017; Lipunov et al. 2017). These multi-messenger observations allow us to use GW170817 as a standard siren (Schutz 1986; Holz & Hughes 2005; Dalal et al. 2006; Nissanke et al. 2010, 2013), the gravitational-wave analog of an astronomical standard candle, to measure the Hubble constant. This quantity, which represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Our measurement combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using electromagnetic data. This approach does not require any form of cosmic 'distance ladder' (Freedman et al. 2001); the gravitational-wave (GW) analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be 70 . 0 +12 . 0 -8 . 0 kms -1 Mpc -1 (maximum a posteriori and 68% credible interval). This is consistent with existing measurements (Planck Collaboration et al. 2016; Riess et al. 2016), while being completely independent of them. Additional standard-siren measurements from future gravitational-wave sources will provide precision constraints of this important cosmological parameter.  \nThe Hubble constant H 0 measures the mean expansion rate of the Universe. At nearby distances ( d glyph[lessorsimilar] 50 Mpc) it is well approximated by the expression  \nv H = H 0 d, (1)  \nwhere v H is the local 'Hubble flow' velocity of a source, and d is the distance to the source. At such distances all cosmological distance measures (such as luminosity distance and comoving distance) differ at the order of v H /c where c is the speed of light. As v H /c ∼ 1% for GW170817 we do not distinguish between them. We are similarly insensitive to the values of other cosmological parameters, such as Ω m and Ω Λ .  \nTo obtain the Hubble flow velocity at the position of GW170817, we use the optical identification of the host galaxy NGC 4993 (Abbott et al. 2017c). This identification is based solely on the 2-dimensional projected offset and is independent of any assumed value of H 0 . The position and redshift of this galaxy allow us to estimate the appropriate value of the Hubble flow velocity. Because the source is relatively nearby the random relative motions of galaxies, known as peculiar velocities, need to be taken into account. The peculiar velocity is ∼ 10% of the measured recessional velocity (see Methods).  \nThe original standard siren proposal (Schutz 1986) did not rely on the unique identification of a host galaxy. By combining information from ∼ 100 independent GW detections, each with a set of potential host galaxies, a ∼ 5% estimate of H 0 can be obtained even without the detection of any transient optical counterparts (Del Pozzo 2012). This is particularly relevant, as gravitational-wave networks will detect many binary black hole mergers over the coming years (Abbott et al. 2016a), and these are not expected to be accompanied by electromagnetic counterparts. Alternatively, if an EM counterpart has been identified but the host galaxy is unknown, the same statistical method can be applied but using only those galaxies in  \na narrow beam around the location of the optical counterpart. However, such statistical analyses are sensitive to a number of complicating effects, including the incompleteness of current galaxy catalogs or the need for dedicated follow-up surveys, as well as a range of selection effects (Messenger & Veitch 2013). In what follows we exploit the identification of NGC 4993 as the host galaxy of GW170817 to perform a standard siren measurement of the Hubble constant (Holz & Hughes 2005; Dalal et al. 2006; Nissanke et al. 2010, 2013).  \nAnalysis of the GW data associated with GW170817 produces estimates for the parameters of the source, under the assumption that general relativity is the correct model of gravity (Abbott et al. 2017a). We are most interested in the joint posterior distribution on the luminosity distance and binary orbital inclination angle. For the analysis in this paper we fix the location of the GW source on the sky to the identified location of the counterpart (Coulter et al. 2017). See the Methods section for details.  \nAn analysis of the GW data alone finds that GW170817occurred at a distance d = 43 . 8 +2 . 9 -6 . 9 Mpc (all values are quoted as the maximum posterior value with the minimal width 68 . 3% credible interval). We note that the distance quoted here differs from that in other studies (Abbott et al. 2017a), since here we assume that the optical counterpart represents the true sky location of the GW source instead of marginalizing over a range of potential sky locations. The ∼ 15% uncertainty is due to a combination of statistical measurement error from the noise in the detectors, instrumental calibration uncertainties (Abbott et al. 2017a), and a geometrical factor dependent upon the correlation of distance with inclination angle. The GW measurement is consistent with the distance to NGC4993 measured using the Tully-Fisher relation, d TF = 41 . 1 ± 5 . 8 Mpc (Sakai et al. 2000; Freedman et al. 2001).  \nThe measurement of the GW polarization is crucial for inferring the binary inclination. This inclination, ι , is defined as the angle between the line of sight vector from the source to the detector and the orbital angular momentum vector of the binary system. For electromagnetic (EM) phenomena it is typically not possible to tell whether a system is orbiting clockwise or counter-clockwise (or, equivalently, face-on or face-off), and sources are therefore usually characterized by a viewing angle: min( ι, 180 · -ι ) . By contrast, GW measurements can identify the sense of the rotation, and thus ι ranges from 0 (counter-clockwise) to 180 deg (clockwise). Previous GW detections by LIGO had large uncertainties in luminosity distance and inclination (Abbott et al. 2016a) because the two LIGO detectors that were involved are nearly co-aligned, preventing a precise polarization measurement. In the present case, thanks to Virgo as an additional detector, the cosine of the inclination can be constrained at 68 . 3% ( 1 σ ) confidence to the range [ -1 . 00 , -0 . 81] corresponding to inclination angles between [144 , 180] deg . This implies that the plane of the binary orbit is almost, but not quite, perpendicular to our line of sight to the source ( ι ≈ 180 deg ), which is consistent with the observation of a coincident GRB (LVC, GBM, & INTEGRAL 2017 in prep.; Goldstein et al. 2017, ApJL, submitted; Savchenko et al. 2017, ApJL, submitted). We report inferences on cos ι because our prior for it is flat, so the posterior is proportional to the marginal likelihood for it from the GW observations.  \nEM follow-up of the GW sky localization region (Abbott et al. 2017c) discovered an optical transient (Coulter et al. 2017; Soares-Santos et al. 2017; Valenti et al. 2017; Arcavi et al. 2017; Tanvir et al. 2017; Lipunov et al. 2017) in close proximity to the galaxy NGC 4993. The location of the transient was previously observed by the Distance Less Than 40 Mpc (DLT40) survey on 2017 July 27.99 UT and no sources were found (Valenti et al. 2017). We estimate the probability  \nFigure 1. GW170817 measurement of H 0 . Marginalized posterior density for H 0 (blue curve). Constraints at 1 - and 2 σ from Planck (Planck Collaboration et al. 2016) and SHoES (Riess et al. 2016) are shown in green and orange. The maximum a posteriori value and minimal 68 . 3% credible interval from this PDF is H 0 = 70 . 0 +12 . 0 -8 . 0 kms -1 Mpc -1 . The 68 . 3% ( 1 σ ) and 95 . 4% ( 2 σ ) minimal credible intervals are indicated by dashed and dotted lines.  \n<!-- image -->  \nof a random chance association between the optical counterpart and NGC 4993 to be 0 . 004% (see the Methods section for details). In what follows we assume that the optical counterpart is associated with GW170817, and that this source resides in NGC4993.  \nTo compute H 0 we need to estimate the background Hubble flow velocity at the position of NGC4993. In the traditional electromagnetic calibration of the cosmic 'distance ladder' (Freedman et al. 2001), this step is commonly carried out using secondary distance indicator information, such as the Tully-Fisher relation (Sakai et al. 2000), which allows one to infer the background Hubble flow velocity in the local Universe scaled back from more distant secondary indicators calibrated in quiet Hubble flow. We do not adopt this approach here, however, in order to preserve more fully the independence of our results from the electromagnetic distance ladder. Instead we estimate the Hubble flow velocity at the position  \nFigure 2. Inference on H 0 and inclination. Posterior density of H 0 and cos ι from the joint GW-EM analysis (blue contours). Shading levels are drawn at every 5% credible level, with the 68 . 3% ( 1 σ , solid) and 95 . 4% ( 2 σ , dashed) contours in black. Values of H 0 and 1 - and 2 σ error bands are also displayed from Planck (Planck Collaboration et al. 2016) and SHoES (Riess et al. 2016). As noted in the text, inclination angles near 180 deg ( cos ι = -1 ) indicate that the orbital angular momentum is anti-parallel with the direction from the source to the detector.  \n<!-- image -->  \nof NGC4993 by correcting for local peculiar motions.  \nNGC4993 is part of a collection of galaxies, ESO-508, whose center-of-mass recession velocity relative to the frame of the CMB (Hinshaw et al. 2009) is (Crook et al. 2007) 3327 ± 72 km s -1 . We correct the group velocity by 310 km s -1 due to the coherent bulk flow (Springob et al. 2014; Carrick et al. 2015) towards The Great Attractor (see Methods section for details). The standard error on our estimate of the peculiar velocity is 69 km s -1 , but recognizing that this value may be sensitive to details of the bulk flow motion that have been imperfectly modelled, in our subsequent analysis we adopt a more conservative estimate (Carrick et al. 2015) of 150kms -1 for the uncertainty on the peculiar velocity at the location of NGC 4993, and fold this into our estimate of the uncertainty on v H . From this, we obtain a Hubble velocity v H = 3017 ± 166 km s -1 .  \nOnce the distance and Hubble velocity distributions have been determined from the GW and EM data, respectively, we can constrain the value of the Hubble constant. The measurement of the distance is strongly correlated with the measurement of the inclination of the orbital plane of the binary. The analysis of the GW data also depends on other parameters describing the source, such as the masses of the components (Abbott et al. 2016a). Here we treat the uncertainty in these other variables by marginalizing over the posterior distribution on system parameters (Abbott et al. 2017a), with the exception of the position of the system on the sky which is taken to be fixed at the location of the optical counterpart.  \nWe carry out a Bayesian analysis to infer a posterior distribution on H 0 and inclination, marginalized over uncertainties in the recessional and peculiar velocities; see the Methods section for details. Figure 1 shows the marginal posterior for H 0 . The maximum a posteriori value with the minimal 68 . 3% credible interval is H 0 = 70 . 0 +12 . 0 -8 . 0 kms -1 Mpc -1 . Our estimate agrees well with state-of-the-art determinations of this quantity, including CMB measurements from Planck (Planck Collaboration et al. 2016) ( 67 . 74 ± 0 . 46 km s -1 Mpc -1 , 'TT,TE,EE+lowP+lensing+ext') and Type Ia supernova measurements from SHoES (Riess et al. 2016) ( 73 . 24 ± 1 . 74 km s -1 Mpc -1 ), as well as baryon acoustic oscillations measurements from SDSS (Aubourg et al. 2015), strong lensing measurements from H0LiCOW (Bonvin et al. 2017), highl CMB measurements from SPT (Henning et al. 2017), and Cepheid measurements from the HST key project (Freedman et al. 2001). Our measurement is a new and independent determination of this quantity. The close agreement indicates that, although each method may be affected by different systematic uncertainties, we see no evidence at present for a systematic difference between GW and established EM-based estimates. As has been much remarked upon, the Planck and SHoES re-  \nlts are inconsistent at glyph[greaterorsimilar] 3 σ level. Our measurement does not resolve this tension, and is broadly consistent with both.  \nOne of the main sources of uncertainty in our measurement of H 0 is due to the degeneracy between distance and inclination in the GW measurements. A face-on or face-off binary far away has a similar gravitational-wave amplitude to an edgeon binary closer in. This relationship is captured in Figure 2, which shows posterior contours in the H 0 -cos ι parameter space.  \nThe posterior in Figure 1 results from the vertical projection of Figure 2, marginalizing out uncertainties in the cosine of inclination to derive constraints on the Hubble constant. Alternatively, it is possible to project horizontally, and thereby marginalize out the Hubble constant to derive constraints on the cosine of inclination. If instead of deriving H 0 independently we take the existing constraints on H 0 (Planck Collaboration et al. 2016; Riess et al. 2016) as priors, we are able to significantly improve our constraints on cos ι as shown in Figure 3. Assuming the Planck value for H 0 , the minimal 68.3% credible interval for the cosine of inclination is [ -1 . 00 , -0 . 92] (corresponding to an inclination angle range [157 , 177] deg ). For the SHoES value of H 0 , it is [ -0 . 97 , -0 . 85] (corresponding to an inclination angle range [148 , 166] deg ). For this latter SHoES result we note that the face-off ι = 180 deg orientation is just outside the 90% confidence range. It will be particularly interesting to compare these constraints to those from modeling of the short GRB, afterglow, and optical counterpart associated with GW170817 (Abbott et al. 2017c).  \nWe have presented a standard siren determination of the Hubble constant, using a combination of a GW distance and an EM Hubble velocity estimate. Our measurement does not use a 'distance ladder', and makes no prior assumptions about H 0 . We find H 0 = 70 . 0 +12 . 0 -8 . 0 kms -1 Mpc -1 , which is consistent with existing measurements (Riess et al. 2016; Planck Collaboration et al. 2016). This  \n(  \ndeg  \n)  \ncos  \nFigure 3. Constraints on the inclination angle of  \n<!-- image -->  \nGW170817. Posterior density on cos ι , for various assumptions about the prior distribution of H 0 . The analysis of the joint GW and EM data with a 1 /H 0 prior density gives the blue curve; using values of H 0 from Planck (Planck Collaboration et al. 2016) and SHoES (Riess et al. 2016) as a prior on H 0 give the green and red curves, respectively. Choosing a narrow prior on H 0 converts the precise Hubble velocity measurements for the group containing NGC 4993 to a precise distance measurement, breaking the distance inclination degeneracy, and leading to strong constraints on the inclination. Minimal 68 . 3% ( 1 σ ) credible intervals are indicated by dashed lines. Because our prior on inclination is flat on cos ι the densities in this plot are proportional to the marginalised likelihood for cos ι .  \nfirst GW-EM multi-messenger event demonstrates the potential for cosmological inference from GW standard sirens. We expect that additional multimessenger binary neutron-star events will be detected in the coming years, and combining subsequent independent measurements of H0 from these future standard sirens will lead to an era of precision gravitational-wave cosmology.", 'PROBABILITY OF OPTICAL COUNTERPART ASSOCIATION WITH NGC4993': "We calculate the probability that an NGC 4993like galaxy (or brighter) is misidentified as the host by asking how often the centre of one or more such galaxies falls by random chance within a given angular radius θ of the counterpart. Assuming Poisson counting statistics this probability is given by P = 1 -exp [ -πθ 2 S ( < m )] where S ( < m ) is the surface density of galaxies with apparent magnitude equal to or brighter than m . From the local galaxy sample distribution in the infrared (Kband) apparent magnitude (Huang et al. 1998) we obtain S ( < K ) = 0 . 68 × 10 (0 . 64( K -10 . 0) -0 . 7) deg -2 . As suggested by (Bloom et al. 2002), we set θ equal to twice the half-light radius of the galaxy, for which we use NGC 4993's diameter of ∼ 1 . 1 arcmin, as measured in the near infrared band (the predominant emission band for early-type galaxies). Using K = 9 . 2 mag taken from the 2MASS survey (Skrutskie et al. 2006) for NGC 4993, we find the probability of random chance association is P = 0 . 004 %.", 'FINDING THE HUBBLE VELOCITY OF NGC4993': "In previous EM determinations of the cosmic 'distance ladder', the Hubble flow velocity of the local calibrating galaxies has generally been estimated using redshift-independent secondary galaxy distance indicators, such as the Tully-Fisher relation or type Ia supernovae, calibrated with more distant samples that can be assumed to sit in quiet Hubble flow (Freedman et al. 2001). We do not adopt this approach for NGC 4993, however, in order that our inference of the Hubble constant is fully independent of the electromagnetic distance scale. Instead we estimate the Hubble flow velocity at the position of NGC 4993 by correcting its measured recessional velocity for local peculiar motions.  \nNGC4993 resides in a group of galaxies whose center-of-mass recession velocity relative to the Cosmic Microwave Background (CMB) frame (Hinshaw et al. 2009) is (Crook et al. 2007, 2008) 3327 ± 72 km s -1 . We assume that all of the galaxies in the group are at the same distance and therefore have the same Hubble flow velocity, which we assign to be the Hubble velocity of GW170817. This assumption is accurate to within 1% given that the radius of the group is ∼ 0 . 4 Mpc. To calculate the Hubble flow velocity of the group, we correct its measured recessional velocity by the peculiar velocity caused by the local gravitational field. This is a significant correction (Springob et al. 2014; Carrick et al. 2015); typical peculiar velocities are 300 km s -1 , equivalent to ∼ 10% of the total recessional velocity at a distance of 40 Mpc.  \nWe employ the 6dF galaxy redshift survey peculiar velocity map (Springob et al. 2014; Jones et al. 2009), which used more than 8,000 Fundamental Plane galaxies to map the peculiar velocity field in the Southern hemisphere out to redshift z glyph[similarequal] 0 . 055 . We weight the peculiar velocity corrections from this catalog with a Gaussian kernel centered on NGC 4993's sky position and with a width of 8 h -1 Mpc ; the kernel width is independent of H 0 and is equivalent to a width of 800 km s -1 in velocity space, typical of the widths used in the catalog itself. There are 10 galaxies in the 6dF peculiar velocity catalog within one kernel width of NGC 4993. In the CMB frame (Hinshaw et al. 2009), the weighted radial component of the peculiar velocity and associated uncertainty is 〈 v p 〉 = 310 ± 69 km s -1 .  \nWe verified the robustness of this peculiar velocity correction by comparing it with the velocity field reconstructed from the 2MASS redshift survey (Carrick et al. 2015; Huchra et al. 2012). This exploits the linear relationship between the peculiar velocity and mass density fields smoothed on scales larger than about 8 h -1 Mpc, and the constant of proportionality can be determined by com-  \nparison with radial peculiar velocities of individual galaxies estimated from e.g. Tully-Fisher and Type Ia supernovae distances. Using these reconstructed peculiar velocities, which have a larger associated uncertainty (Carrick et al. 2015) of 150 km s -1 , at the position of NGC 4993 we find a Hubble velocity in the CMB frame of v H = 3047kms -1 - in excellent agreement with the result derived using 6dF. We adopt this larger uncertainty on the peculiar velocity correction in recognition that the peculiar velocity estimated from the 6dF data may represent an imperfect model of the true bulk flow at the location of NGC 4993. For our inference of the Hubble constant we therefore use a Hubble velocity v H = 3017 ± 166 km s -1 with 68.3% uncertainty.  \nFinally, while we emphasise again the independence of our Hubble constant inference from the electromagnetic distance scale, we note the consistency of our GW distance estimate to NGC 4993 with the Tully-Fisher distance estimate derived by scaling back the Tully-Fisher relation calibrated with more distant galaxies in quiet Hubble flow (Sakai et al. 2000). This also strongly supports the robustness of our estimate for the Hubble velocity of NGC4993.", 'SUMMARY OF THE MODEL': "Given observed data from a set of GW detectors, x GW , parameter estimation is used to generate a posterior on the parameters that determine the waveform of the GW signal. Parameters are inferred within a Bayesian framework (Veitch et al. 2015) by comparing strain measurements (Abbott et al. 2017a) in the two LIGO detectors and the Virgo detector with the gravitational waveforms expected from the inspiral of two point masses (Hannam et al. 2014) under general relativity. We use algorithms for removing short-lived detector noise artifacts (Abbott et al. 2017a; Cornish & Littenberg 2015) and we employ approximate pointparticle waveform models (Buonanno & Damour 1999; Blanchet 2014; Hannam et al. 2014). We have verified that the systematic changes in the re-  \nsults presented here from incorporating non-pointmass (tidal) effects (Hinderer & Flanagan 2008; Vines et al. 2011) and from different data processing methods are much smaller than the statistical uncertainties in the measurement of H 0 and the binary orbital inclination angle.  \nFrom this analysis we can obtain the parameter estimation likelihood of the observed GW data, marginalized over all parameters characterizing the GWsignal except d and cos ι ,  \np ( x GW | d, cos ι ) = ∫ p ( x GW | d, cos ι, glyph[vector] λ ) p ( glyph[vector] λ )d glyph[vector] λ. (2)  \nThe other waveform parameters are denoted by glyph[vector] λ , with p ( glyph[vector] λ ) denoting the corresponding prior.  \nGiven perfect knowledge of the Hubble flow velocity of the GW source, v H , this posterior distribution can be readily converted into a posterior on cos ι and H 0 = v H /d ,  \np ( H 0 , cos ι | x GW ) ∝ ( v H /H 2 0 ) p ( x GW | d = v H /H 0 , cos ι ) × p d ( v H /H 0 ) p ι (cos ι ) , (3)  \nwhere p d ( d ) and p ι (cos ι ) are the prior distributions on distance and inclination. For the Hubble velocity v H = 3017kms -1 , the maximum a posteriori distance from the GW measurement of 43 . 8 Mpc corresponds to H 0 = 68 . 9 km s -1 Mpc -1 , so this procedure would be expected to generate a posterior on H 0 that peaks close to that value.  \nWhile the above analysis is conceptually straightforward, it makes a number of assumptions. In practice, the Hubble-flow velocity cannot be determined exactly and it must be corrected for uncertain peculiar velocities. The above does not explicitly set a prior on H 0 , but instead inherits a 1 /H 4 0 prior from the usual p d ( d ) ∝ d 2 prior used in GW parameter estimation. In addition, the logic in this model is that a redshift has been obtained first and the distance is then measured using GWs. As GW detectors cannot be pointed,  \nwe cannot target particular galaxies or redshifts for GW sources. In practice, we wait for a GW event to trigger the analysis and this introduces potential selection effects which we must consider. We will see below that the simple analysis described above does give results that are consistent with a more careful analysis for this first detection. However, the simple analysis cannot be readily extended to include second and subsequent detections, so we now describe a more general framework that does not suffer from these limitations.  \nWe suppose that we have observed a GW event, which generated data x GW in our detectors, and that we have also measured a recessional velocity for the host, v r , and the peculiar velocity field, 〈 v p 〉 , in the vicinity of the host. These observations are statistically independent and so the combined likelihood is  \np ( x GW , v r , 〈 v p 〉 | d, cos ι, v p , H 0 ) = p ( x GW | d, cos ι ) p ( v r | d, v p , H 0 ) p ( 〈 v p 〉 | v p ) . (4)  \nThe quantity p ( v r | d, v p , H 0 ) is the likelihood of the recessional velocity measurement, which we model as  \np ( v r | d, v p , H 0 ) = N [ v p + H 0 d, σ 2 v r ] ( v r ) (5)  \nwhere N [ µ, σ 2 ] ( x ) is the normal (Gaussian) probability density with mean µ and standard deviation σ evaluated at x . The measured recessional velocity, v r = 3327kms -1 , with uncertainty σ v r = 72 km s -1 , is the mean velocity and standard error for the members of the group hosting NGC 4993 taken from the two micron all sky survey (2MASS) (Crook et al. 2007, 2008), corrected to the CMB frame (Hinshaw et al. 2009). We take a similar Gaussian likelihood for the measured peculiar velocity, 〈 v p 〉 = 310kms -1 , with uncertainty σ v p = 150 km s -1 :  \np ( 〈 v p 〉 | v p ) = N [ v p , σ 2 v p ] ( 〈 v p 〉 ) . (6)  \nFrom the likelihood (4) we derive the posterior  \np ( H 0 , d, cos ι, v p | x GW , v r , 〈 v p 〉 ) ∝ p ( H 0 ) N s ( H 0 ) p ( x GW | d, cos ι ) p ( v r | d, v p , H 0 ) × p ( 〈 v p 〉 | v p ) p ( d ) p ( v p ) p (cos ι ) , (7)  \nwhere p ( H 0 ) , p ( d ) , p ( v p ) and p (cos ι ) are the parameter prior probabilities. Our standard analysis assumes a volumetric prior, p ( d ) ∝ d 2 , on the Hubble distance, but we explore sensitivity to this choice below. We take a flat-in-log prior on H 0 , p ( H 0 ) ∝ 1 /H 0 , impose a flat (i.e. isotropic) prior on cos ι , and a flat prior on v p for v p ∈ [ -1000 , 1000] km s -1 . These priors characterise our beliefs about the cosmological population of GW events and their hosts before we make any additional measurements or account for selection biases. The full statistical model is summarized graphically in Extended Data Figure 1. This model with these priors is our canonical analysis.  \nIn Eq. (7), the term N s ( H 0 ) encodes selection effects (Loredo 2004; Mandel et al. 2016; Abbott et al. 2016a). These arise because of the finite sensitivity of our detectors. While all events in the Universe generate a response in the detector, we will only be able to identify, and hence use, signals that generate a response of sufficiently high amplitude. The decision about whether to include an event in the analysis is a property of the data only, in this case { x GW , v r , 〈 v p 〉} , but the fact that we condition our analysis on a signal being detected, i.e., the data exceeding these thresholds, means that the likelihood must be renormalized to become the likelihood for detected events. This is the role of  \nN s ( H 0 ) = ∫ d glyph[vector] λ d d d v p dcos ι d x GW d v r d 〈 v p 〉  \ndetectable × [ p ( x GW | d, cos ι, glyph[vector] λ ) p ( v r | d, v p , H 0 ) × p ( 〈 v p 〉 | v p ) p ( glyph[vector] λ ) p ( d ) p ( v p ) p (cos ι ) ] , (8)  \nwhere the integral is over the full prior ranges of the parameters, { d, v p , cos ι, glyph[vector] λ } , and over data sets  \nthat would be selected for inclusion in the analysis, i.e., exceed the specified thresholds. If the integral was over all data sets it would evaluate to 1 , but because the range is restricted there can be a non-trivial dependence on parameters characterizing the population of sources, in this case H 0 .  \nIn the current analysis, there are in principle selection effects in both the GW data and the EM data. However, around the time of detection of GW170817, the LIGO-Virgo detector network had a detection horizon of ∼ 190 Mpc for binary neutron star (BNS) events (Abbott et al. 2017a), within which EM measurements are largely complete. For example, the counterpart associated with GW170817 had brightness ∼ 17 mag in the I band at 40 Mpc (Valenti et al. 2017; Arcavi et al. 2017; Tanvir et al. 2017; Lipunov et al. 2017; Coulter et al. 2017); this source would be ∼ 22 mag at 400 Mpc, and thus still detectable by survey telescopes such as DECam well beyond the GW horizon. Even the dimmest theoretical lightcurves for kilonovae are expected to peak at ∼ 22 . 5 mag at the LIGO-Virgo horizon (Metzger & Berger 2012). We therefore expect that we are dominated by GW selection effects at the current time and can ignore EM selection effects. The fact that the fraction of BNS events that will have observed kilonova counterparts is presently unknown does not modify these conclusions, since we can restrict our analysis to GW events with kilonova counterparts only.  \nIn the GW data, the decision about whether or not to analyse an event is largely determined by the signal-to-noise ratio (SNR), ρ , of the event. A reasonable model for the selection process is a cut in SNR, i.e., events with ρ > ρ ∗ are analysed (Abbott et al. 2016b). In that model, the integral over x GW in Eq. (8) can be replaced by an integral over SNR from ρ ∗ to ∞ , and p ( x GW | d, cos ι, glyph[vector] λ ) replaced by p ( ρ | d, cos ι, glyph[vector] λ ) in the integrand. This distribution depends on the noise properties of the operating detectors, and on the intrinsic strain amplitude of the source. The former are clearly independent of  \nthe population parameters, while the latter scales like a function of the source parameters divided by the luminosity distance. The dependence on source parameters is on redshifted parameters, which introduces an explicit redshift dependence. However, within the ∼ 190 Mpc horizon, redshift corrections are at most glyph[lessorsimilar] 5% , and the Hubble constant measurement is a weak function of these, meaning the overall impact is even smaller. At present, whether or not a particular event in the population ends up being analysed can therefore be regarded as a function of d only. When GW selection effects dominate, only the terms in Eq. (8) arising from the GW measurement matter. As these are a function of d only and we set a prior on d , there is no explicit H 0 dependence in these terms. Hence, N s ( H 0 ) is a constant and can be ignored. This would not be the case if we set a prior on the redshifts of potential sources instead of their distances, since then changes in H 0 would modify the range of detectable redshifts. As the LIGO-Virgo detectors improve in sensitivity the redshift dependence in the GW selection effects will become more important, as will EM selection effects. However, at that point we will also have to consider deviations in the cosmological model from the simple Hubble flow described in Eq. (1) of the main article.  \nMarginalising Eq. (7) over d , v p and cos ι then yields  \n∫  \np ( H 0 | x GW , v r , 〈 v p 〉 ) ∝ p ( H 0 ) d d d v p dcos ι × p ( x GW | d, cos ι ) p ( v r | d, v p , H 0 ) × p ( 〈 v p 〉 | v p ) p ( d ) p ( v p ) p (cos ι ) . (9)  \nThe posterior computed in this way was shown in Figure 1 in the main article and has a maximum a posteriori value and minimal 68 . 3% credible interval of 70 . 0 +12 . 0 -8 . 0 kms -1 Mpc -1 , as quoted in the main article. The posterior mean is 78 km s -1 Mpc -1 and the standard deviation is 15 km s -1 Mpc -1 . Various other summary statistics are given in Extended Data Table 1.  \nROBUSTNESS TO PRIOR SPECIFICATION  \n<!-- image -->  \nExtended Data Figure 1. Graphical model illustrating the statistical relationships between the data and parameters. Open circles indicate parameters which require a prior; filled circles described measured data, which are conditioned on in the analysis. Here we assume we have measurements of the GW data, x GW , a recessional velocity (i.e. redshift), v r , and the mean peculiar velocity in the neighborhood of NGC 4993, 〈 v p 〉 . Arrows flowing into a node indicate that the conditional probability density for the node depends on the source parameters; for example, the conditional distribution for the observed GW data, p ( x GW | d, cos ι ) , discussed in the text, depends on the distance and inclination of the source (and additional parameters, here marginalized out).  \nOur canonical analysis uses a uniform volumetric prior on distance, p ( d ) ∝ d 2 . The distribution of galaxies is not completely uniform due to clustering, so we explore sensitivity to this prior choice. We are free to place priors on any two of the three variables { d, H 0 , z } , where z = H 0 d/c is the Hubble flow redshift of NGC 4993. A choice of prior for two of these variables induces a prior on the third which may or may not correspond to a natural choice for that parameter. A prior on z could be obtained from galaxy catalog observations (Dalya et al. 2016), but must be corrected for incompleteness. When setting a prior on H 0 and z ,  \nthe posterior becomes  \np ( H 0 , z, cos ι, v p | x GW , v r , 〈 v p 〉 ) ∝ p ( H 0 ) N s ( H 0 ) p ( x GW | d = cz/H 0 , cos ι ) p ( v r | z, v p ) × p ( 〈 v p 〉 | v p ) p ( z ) p ( v p ) p (cos ι ) , (10)  \nbut now  \nN s ( H 0 ) = ∫ detectable d z d v p dcos ι d x GW d v r d 〈 v p 〉 × p ( x GW | d = cz/H 0 , cos ι ) p ( v r | z, v p ) × p ( 〈 v p 〉 | v p ) p ( z ) p ( v p ) p (cos ι ) . (11)  \nWhen GW selection effects dominate, the integral is effectively  \nN s ( H 0 ) = ∫ d z dcos ι d x GW × p ( x GW | d = cz/H 0 , cos ι ) p ( z ) p (cos ι ) = ∫ d d dcos ι d x GW × p ( x GW | d, cos ι ) p ( dH 0 /c ) p (cos ι ) ( H 0 /c ) , (12)  \nwhich has an H 0 dependence, unless p ( z ) takes a special, H 0 -dependent form, p ( z ) = f ( z/H 0 ) /H 0 . However, if the redshift prior is volumetric, p ( z ) ∝ z 2 , the selection effect term is ∝ H 3 0 , which cancels a similar correction to the likelihood and gives a posterior on H 0 that is identical to the canonical analysis.  \nFor a single event, any choice of prior can be mapped to our canonical analysis with a different prior on H 0 . For any reasonable prior choices on d or z , we would expect to gradually lose sensitivity to the particular prior choice as further observed events are added to the analysis. However, to illustrate the uncertainty that comes from the prior choice for this first event, we compare in Extended Data Figure 2 and Extended Data Table 1 the results from the canonical prior choice p ( d ) ∝ d 2 to those from two other choices: using a flat prior  \non z , and assuming a velocity correction due to the peculiar velocity of NGC 4993 that is a Gaussian with width 250 km s -1 . (To do the first of these, the posterior samples from GW parameter estimation have to be re-weighted, since they are generated with the d 2 prior used in the canonical analysis. We first 'undo' the default prior before applying the desired new prior.)  \nThe choice of a flat prior on z is motivated by the simple model described above, in which we imagine first making a redshift measurement for the host and then use that as a prior for analysing the GW data. Setting priors on distance and redshift, the simple analysis gives the same result as the canonical analysis, but now we set a prior on redshift and H 0 and obtain a different result. This is to be expected because we are making different assumptions about the underlying population, and it arises for similar reasons as the different biases in peculiar velocity measurements based on redshiftselected or distance-selected samples (Strauss & Willick 1995). As can be seen in Extended Data Table 1, the results change by less than 1 σ , as measured by the statistical error of the canonical analysis.  \nBy increasing the uncertainty in the peculiar velocity prior, we test the assumptions in our canonical analysis that (1) NGC 4993 is a member of the nearby group of galaxies, and (2) that this group has a center-of-mass velocity close to the Hubble flow. The results in Extended Data Table 1 summarizes changes in the values of H 0 and in the error bars.  \nWe conclude that the impact of a reasonable change to the prior is small relative to the statistical uncertainties for this event.", 'INCORPORATING ADDITIONAL CONSTRAINTS ON H 0': "By including previous measurements of H 0 (Planck Collaboration et al. 2016; Riess et al. 2016) we can constrain the orbital inclination more precisely. We do this by setting the H 0 prior in Eq. (7) to p ( H 0 | µ H 0 , σ 2 H 0 ) = N [ µ H 0 , σ 2 H 0 ] ,  \n<!-- image -->  \nExtended Data Figure 2. Using different assumptions compared to our canonical analysis. The posterior distribution on H 0 discussed in the main text is shown in black, the alternative flat prior on z (discussed in the Methods section) gives the distribution shown in blue, and the increased uncertainty ( 250 kms -1 ) applied to our peculiar velocity measurement (also discussed in the Methods section) is shown in pink. Minimal 68 . 3% ( 1 σ ) credible intervals are shown by dashed lines.  \nwhere for ShoES (Riess et al. 2016) µ H 0 = 73 . 24 km s -1 Mpc -1 and σ H 0 = 1 . 74 km s -1 Mpc -1 , while for Planck (Planck Collaboration et al. 2016) µ H 0 = 67 . 74 km s -1 Mpc -1 and σ H 0 = 0 . 46 km s -1 Mpc -1 . The posterior on cos ι is then  \np (cos ι | x GW , v r , 〈 v p 〉 , µ H 0 , σ 2 H 0 ) ∝ ∫ d d d v p d H 0 × p ( x GW | d, cos ι ) p ( v r | d, v p , H 0 ) p ( 〈 v p 〉 | v p ) × p ( H 0 | µ H 0 , σ 2 H 0 ) p ( d ) p ( v p ) . (13)  \nThis posterior was shown in Figure 3 of the main article.  \nThe authors gratefully acknowledge the support of the United States National Science Foundation (NSF) for the construction and operation of the LIGO Laboratory and Advanced LIGO as well as the Science and Technology Facilities Council (STFC) of the United Kingdom, the MaxPlanck-Society (MPS), and the State of Niedersachsen/Germany for support of the construction  \nExtended Data Table 1. Summary of constraints on the Hubble constant, binary inclination, and distance  \nNOTE-We give both one-sigma (68.3%) and 90% credible intervals for each quantity. 'Symm.' refers to a symmetric interval (e.g. median and 5% to 95% range), while 'MAP' refers to maximum a posteriori intervals (e.g. MAP value and smallest range enclosing 90% of the posterior). Values given for ι are derived from arc-cosine transforming the corresponding values for cos ι , so the 'MAP' values differ from those that would be derived from the posterior on ι .  \nof Advanced LIGO and construction and operation of the GEO600 detector. Additional support for Advanced LIGO was provided by the Australian Research Council. The authors gratefully acknowledge the Italian Istituto Nazionale di Fisica Nucleare (INFN), the French Centre National de la Recherche Scientifique (CNRS) and the Foundation for Fundamental Research on Matter supported by the Netherlands Organisation for Scientific Research, for the construction and operation of the Virgo detector and the creation and support of the EGO consortium. The authors also gratefully acknowledge research support from these agencies as well as by the Council of Scientific and Industrial Research of India, the Department of Science and Technology, India, the Science & Engineering Research Board (SERB), India, the Ministry of Human Resource Development, India, the Spanish Agencia Estatal de Investigaci'on, the Vicepresid'encia i Conselleria d'Innovaci'o, Re-  \nrca i Turisme and the Conselleria d'Educaci'o i Universitat del Govern de les Illes Balears, the Conselleria d'Educaci'o, Investigaci'o, Cultura i Esport de la Generalitat Valenciana, the National Science Centre of Poland, the Swiss National Science Foundation (SNSF), the Russian Foundation for Basic Research, the Russian Science Foundation, the European Commission, the European Regional Development Funds (ERDF), the Royal Society, the Scottish Funding Council, the Scottish Universities Physics Alliance, the Hungarian Scientific Research Fund (OTKA), the Lyon Institute of Origins (LIO), the National Research, Development and Innovation Office Hungary (NKFI), the National Research Foundation of Korea, Industry Canada and the Province of Ontario through the Ministry of Economic Development and Innovation, the Natural Science and Engineering Research Council Canada, the Canadian Institute for Advanced Research, the Brazilian Ministry of  \nScience, Technology, Innovations, and Communications, the International Center for Theoretical Physics South American Institute for Fundamental Research (ICTP-SAIFR), the Research Grants Council of Hong Kong, the National Natural Science Foundation of China (NSFC), the Leverhulme Trust, the Research Corporation, the Ministry of Science and Technology (MOST), Taiwan and the Kavli Foundation. The authors gratefully acknowledge the support of the NSF, STFC, MPS, INFN, CNRS and the State of Niedersachsen/Germany for provision of computational resources. This article has been assigned the document number LIGO-P1700296.  \nWe thank the University of Copenhagen, DARK Cosmology Centre, and the Niels Bohr International Academy for hosting D.A.C., R.J.F., A.M.B., E.R., and M.R.S. during the discovery of GW170817/SSS17a. R.J.F., A.M.B., E.R., and D.E.H. were participating in the Kavli Summer Program in Astrophysics, 'Astrophysics with gravitational wave detections.' This program was supported by the the Kavli Foundation, Danish National Research Foundation, the Niels Bohr International Academy, and the DARK Cosmology Centre.  \nThe UCSC group is supported in part by NSF grant AST-1518052, the Gordon & Betty Moore Foundation, the Heising-Simons Foundation, generous donations from many individuals through a UCSC Giving Day grant, and from fellowships from the Alfred P. Sloan Foundation (R.J.F), the David and Lucile Packard Foundation (R.J.F. and E.R.) and the Niels Bohr Professorship from the DNRF (E.R.). A.M.B. acknowledges support from a UCMEXUS-CONACYT Doctoral Fellowship. Support for this work was provided by NASA through Hubble Fellowship grants HSTHF-51348.001 and HST-HF-51373.001 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555.  \nThe Berger Time-Domain Group at Harvard is supported in part by the NSF through grants AST-1411763 and AST-1714498, and by NASA through grants NNX15AE50G and NNX16AC22G.  \nFunding for the DES Projects has been provided by the DOE and NSF (USA), MEC, MICINN, MINECO (Spain), STFC (UK), HEFCE (UK), NCSA(UIUC), KICP (U. Chicago), CCAPP (Ohio State), MIFPA (Texas A&M), CNPQ, FAPERJ, FINEP (Brazil), DFG (Germany) and the Collaborating Institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne Lab, UC Santa Cruz, University of Cambridge, CIEMATMadrid, University of Chicago, University College London, DES-Brazil Consortium, University of Edinburgh, ETH Zurich, Fermilab, University of Illinois, ICE (IEEC-CSIC), IFAE Barcelona, Lawrence Berkeley Lab, LMU Munchen and the associated Excellence Cluster Universe, University of Michigan, NOAO, University of Nottingham, Ohio State University, University of Pennsylvania, University of Portsmouth, SLAC National Lab, Stanford University, University of Sussex, Texas A&M University, and the OzDES Membership Consortium. Based in part on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. The DES Data Management System is supported by the NSF under Grant Numbers AST-1138766 and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA201571825, ESP2015-88861, FPA2015-68048, and Centro de Excelencia SEV-2012-0234, SEV-20160597 and MDM-2015-0509. Research leading to these results has received funding from the ERC under the EU's 7 th Framework Programme including grants ERC 240672, 291329 and 306478. We acknowledge support from the Australian Research Council Centre of Excellence for All-sky  \nAstrophysics (CAASTRO), through project number CE110001020. This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paidup, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.  \nD.J.S. acknowledges support for the DLT40 program from NSF grant AST-1517649.  \nSupport for I.A. was provided by NASA through the Einstein Fellowship Program, grant PF6170148. G.H., D.A.H. and C.M. are supported by NSF grant AST-1313484. D.P. acknowledges support by Israel Science Foundation grant 541/17.  \nVINROUGE is an European Southern Observatory Large Survey (id: 0198.D-2010).  \nMASTER acknowledges the Lomonosov MSU Development Programm and the Russian Federation Ministry of Education and Science.  \nThis research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.  \nAll authors contributed to the work presented in this paper.  \nThe authors declare that they have no competing financial interests.  \nCorrespondence and requests for materials should be addressed to the LVC spokespeople (email: lscspokesperson@ligo.org, virgo-spokesperson@egogw.eu).  \nAvailable public codes can be found at the LIGO Open Science Center ( https://losc.ligo. org ).  \nAvailable public data can be found at the LIGO Open Science Center ( https://losc.ligo. org ).", 'All Authors and Affiliations': "THE LIGO SCIENTIFIC COLLABORATION AND THE VIRGO COLLABORATION, THE 1M2H COLLABORATION, THE DARK ENERGY CAMERA GW-EM COLLABORATION AND THE DES COLLABORATION,  \nTHE DLT40 COLLABORATION, THE LAS CUMBRES OBSERVATORY COLLABORATION,  \nTHE VINROUGE COLLABORATION, THE MASTER COLLABORATION, B. P. ABBOTT, 1 R. ABBOTT, 1 T. D. ABBOTT, 2 F. ACERNESE, 3, 4 K. ACKLEY, 5, 6 C. ADAMS, 7 T. ADAMS, 8 P. ADDESSO, 9 R. X. ADHIKARI, 1 V. B. ADYA, 10 C. AFFELDT, 10 M. AFROUGH, 11 B. AGARWAL, 12 M. AGATHOS, 13 K. AGATSUMA, 14 N. AGGARWAL, 15 O. D. AGUIAR, 16 L. AIELLO, 17, 18 A. AIN, 19 P. AJITH, 20 B. ALLEN, 10, 21, 22 G. ALLEN, 12 A. ALLOCCA, 23, 24 P. A. ALTIN, 25 A. AMATO, 26 A. ANANYEVA, 1 S. B. ANDERSON, 1 W. G. ANDERSON, 21 S. V. ANGELOVA, 27 S. ANTIER, 28 S. APPERT, 1 K. ARAI, 1 M. C. ARAYA, 1 J. S. AREEDA, 29 N. ARNAUD, 28, 30 K. G. ARUN, 31 S. ASCENZI, 32, 33 G. ASHTON, 10 M. AST, 34 S. M. ASTON, 7 P. ASTONE, 35 D. V. ATALLAH, 36 P. AUFMUTH, 22 C. AULBERT, 10 K. AULTONEAL, 37 C. AUSTIN, 2 A. AVILA-ALVAREZ, 29 S. BABAK, 38 P. BACON, 39 M. K. M. BADER, 14 S. BAE, 40 P. T. BAKER, 41 F. BALDACCINI, 42, 43 G. BALLARDIN, 30 S. W. BALLMER, 44 S. BANAGIRI, 45 J. C. BARAYOGA, 1 S. E. BARCLAY, 46 B. C. BARISH, 1 D. BARKER, 47 K. BARKETT, 48 F. BARONE, 3, 4 B. BARR, 46 L. BARSOTTI, 15 M. 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BRINKMANN, 10 V. BRISSON, 28 P. BROCKILL, 21 J. E. BROIDA, 71 A. F. BROOKS, 1 D. A. BROWN, 44 D. D. BROWN, 72 S. BRUNETT, 1 C. C. BUCHANAN, 2 A. BUIKEMA, 15 T. BULIK, 73 H. J. BULTEN, 74, 14 A. BUONANNO, 38, 75 D. BUSKULIC, 8 C. BUY, 39 R. L. BYER, 51 M. CABERO, 10 L. CADONATI, 76 G. CAGNOLI, 26, 77 C. CAHILLANE, 1 J. CALDER 'ON BUSTILLO, 76 T. A. CALLISTER, 1 E. CALLONI, 78, 4 J. B. CAMP, 79 M. CANEPA, 80, 59 P. CANIZARES, 65 K. C. CANNON, 81 H. CAO, 72 J. CAO, 82 C. D. CAPANO, 10 E. CAPOCASA, 39 F. CARBOGNANI, 30 S. CARIDE, 83 M. F. CARNEY, 84 J. CASANUEVA DIAZ, 28 C. CASENTINI, 32, 33 S. CAUDILL, 21, 14 M. CAVAGLI'A, 11 F. CAVALIER, 28 R. CAVALIERI, 30 G. CELLA, 24 C. B. CEPEDA, 1 P. CERD 'A-DUR 'AN, 85 G. CERRETANI, 23, 24 E. CESARINI, 86, 33 S. J. CHAMBERLIN, 63 M. CHAN, 46 S. CHAO, 87 P. CHARLTON, 88 E. CHASE, 89 E. CHASSANDE-MOTTIN, 39 D. CHATTERJEE, 21 K. CHATZIIOANNOU, 90 B. D. CHEESEBORO, 41 H. Y. CHEN, 91 X. CHEN, 64 Y. CHEN, 48 H.-P. CHENG, 5 H. CHIA, 5 A. CHINCARINI, 59 A. CHIUMMO, 30 T. CHMIEL, 84 H. S. CHO, 92 M. CHO, 75 J. H. CHOW, 25 N. CHRISTENSEN, 71, 66 Q. CHU, 64 A. J. K. CHUA, 13 S. CHUA, 70 A. K. W. CHUNG, 93 S. CHUNG, 64 G. CIANI, 5, 53, 54 R. CIOLFI, 94, 95 C. E. CIRELLI, 51 A. CIRONE, 80, 59 F. CLARA, 47 J. A. CLARK, 76 P. CLEARWATER, 96 F. CLEVA, 66 C. COCCHIERI, 11 E. COCCIA, 17, 18 P.-F. COHADON, 70 D. COHEN, 28 A. COLLA, 97, 35 C. G. COLLETTE, 98 L. R. COMINSKY, 99 M. CONSTANCIO JR., 16 L. CONTI, 54 S. J. COOPER, 58 P. CORBAN, 7 T. R. CORBITT, 2 I. CORDERO-CARRI'ON, 100 K. R. CORLEY, 50 N. CORNISH, 101 A. CORSI, 83 S. CORTESE, 30 C. A. COSTA, 16 M. W. COUGHLIN, 71, 1 S. B. COUGHLIN, 89 J.-P. COULON, 66 S. T. COUNTRYMAN, 50 P. COUVARES, 1 P. B. COVAS, 102 E. E. COWAN, 76 D. M. COWARD, 64 M. J. COWART, 7 D. C. COYNE, 1 R. COYNE, 83 J. D. E. CREIGHTON, 21 T. D. CREIGHTON, 103 J. CRIPE, 2 S. G. CROWDER, 104 T. J. CULLEN, 29, 2 A. CUMMING, 46 L. CUNNINGHAM, 46 E. CUOCO, 30 T. DAL CANTON, 79 G. D 'ALYA, 55 S. L. DANILISHIN, 22, 10 S. D'ANTONIO, 33 K. DANZMANN, 22, 10 A. DASGUPTA, 105 C. F. DA SILVA COSTA, 5 L. E. H. DATRIER, 46 V. DATTILO, 30 I. DAVE, 60 M. DAVIER, 28 D. DAVIS, 44 E. J. DAW, 106 B. DAY, 76 S. DE, 44 D. DEBRA, 51  \nJ. DEGALLAIX, 26 M. DE LAURENTIS, 17, 4 S. DEL'EGLISE, 70 W. DEL POZZO, 58, 23, 24 N. DEMOS, 15 T. DENKER, 10 T. DENT, 10 R. DE PIETRI, 107, 108 V. DERGACHEV, 38 R. DE ROSA, 78, 4 R. T. DEROSA, 7 C. DE ROSSI, 26, 30 R. DESALVO, 109 O. DE VARONA, 10 J. DEVENSON, 27 S. DHURANDHAR, 19 M. C. D'IAZ, 103 L. DI FIORE, 4 M. DI GIOVANNI, 110, 95 T. DI GIROLAMO, 50, 78, 4 A. DI LIETO, 23, 24 S. DI PACE, 97, 35 I. DI PALMA, 97, 35 F. DI RENZO, 23, 24 Z. DOCTOR, 91 V. DOLIQUE, 26 F. DONOVAN, 15 K. L. DOOLEY, 11 S. DORAVARI, 10 I. DORRINGTON, 36 R. DOUGLAS, 46 M. DOVALE ' ALVAREZ, 58 T. P. DOWNES, 21 M. DRAGO, 10 C. DREISSIGACKER, 10 J. C. DRIGGERS, 47 Z. DU, 82 M. DUCROT, 8 P. DUPEJ, 46 S. E. DWYER, 47 T. B. EDO, 106 M. C. EDWARDS, 71 A. EFFLER, 7 H.-B. EGGENSTEIN, 38, 10 P. EHRENS, 1 J. EICHHOLZ, 1 S. S. EIKENBERRY, 5 R. A. EISENSTEIN, 15 R. C. ESSICK, 15 D. ESTEVEZ, 8 Z. B. ETIENNE, 41 T. ETZEL, 1 M. EVANS, 15 T. M. EVANS, 7 M. FACTOUROVICH, 50 V. FAFONE, 32, 33, 17 H. FAIR, 44 S. FAIRHURST, 36 X. FAN, 82 S. FARINON, 59 B. FARR, 91 W. M. FARR, 58 E. J. FAUCHON-JONES, 36 M. FAVATA, 111 M. FAYS, 36 C. FEE, 84 H. FEHRMANN, 10 J. FEICHT, 1 M. M. FEJER, 51 A. FERNANDEZ-GALIANA, 15 I. FERRANTE, 23, 24 E. C. FERREIRA, 16 F. FERRINI, 30 F. FIDECARO, 23, 24 D. FINSTAD, 44 I. FIORI, 30 D. FIORUCCI, 39 M. FISHBACH, 91 R. P. FISHER, 44 M. FITZ-AXEN, 45 R. FLAMINIO, 26, 112 M. FLETCHER, 46 H. FONG, 90 J. A. FONT, 85, 113 P. W. F. FORSYTH, 25 S. S. FORSYTH, 76 J.-D. FOURNIER, 66 S. FRASCA, 97, 35 F. FRASCONI, 24 Z. FREI, 55 A. FREISE, 58 R. FREY, 69 V. FREY, 28 E. M. FRIES, 1 P. FRITSCHEL, 15 V. V. FROLOV, 7 P. FULDA, 5 M. FYFFE, 7 H. GABBARD, 46 B. U. GADRE, 19 S. M. GAEBEL, 58 J. R. GAIR, 114 L. GAMMAITONI, 42 M. R. GANIJA, 72 S. G. GAONKAR, 19 C. GARCIA-QUIROS, 102 F. GARUFI, 78, 4 B. GATELEY, 47 S. GAUDIO, 37 G. GAUR, 115 V. GAYATHRI, 116 N. GEHRELS, 79, ∗ G. GEMME, 59 E. GENIN, 30 A. GENNAI, 24 D. GEORGE, 12 J. GEORGE, 60 L. GERGELY, 117 V. GERMAIN, 8 S. GHONGE, 76 ABHIRUP GHOSH, 20 ARCHISMAN GHOSH, 20, 14 S. GHOSH, 65, 14, 21 J. A. GIAIME, 2, 7 K. D. GIARDINA, 7 A. GIAZOTTO, 24 K. GILL, 37 L. GLOVER, 109 E. GOETZ, 118 R. GOETZ, 5 S. GOMES, 36 B. GONCHAROV, 6 G. GONZ'ALEZ, 2 J. M. GONZALEZ CASTRO, 23, 24 A. GOPAKUMAR, 119 M. L. GORODETSKY, 61 S. E. GOSSAN, 1 M. GOSSELIN, 30 R. GOUATY, 8 A. GRADO, 120, 4 C. GRAEF, 46 M. GRANATA, 26 A. GRANT, 46 S. GRAS, 15 C. GRAY, 47 G. GRECO, 121, 122 A. C. GREEN, 58 E. M. GRETARSSON, 37 P. GROOT, 65 H. GROTE, 10 S. GRUNEWALD, 38 P. GRUNING, 28 G. M. GUIDI, 121, 122 X. GUO, 82 A. GUPTA, 63 M. K. GUPTA, 105 K. E. GUSHWA, 1 E. K. GUSTAFSON, 1 R. GUSTAFSON, 118 O. HALIM, 18, 17 B. R. HALL, 68 E. D. HALL, 15 E. Z. HAMILTON, 36 G. HAMMOND, 46 M. HANEY, 123 M. M. HANKE, 10 J. HANKS, 47 C. HANNA, 63 M. D. HANNAM, 36 O. A. HANNUKSELA, 93 J. HANSON, 7 T. HARDWICK, 2 J. HARMS, 17, 18 G. M. HARRY, 124 I. W. HARRY, 38 M. J. HART, 46 C.-J. HASTER, 90 K. HAUGHIAN, 46 J. HEALY, 57 A. HEIDMANN, 70 M. C. HEINTZE, 7 H. HEITMANN, 66 P. HELLO, 28 G. HEMMING, 30 M. HENDRY, 46 I. S. HENG, 46 J. HENNIG, 46 A. W. HEPTONSTALL, 1 M. HEURS, 10, 22 S. HILD, 46 T. HINDERER, 65 D. HOAK, 30 D. HOFMAN, 26 K. HOLT, 7 D. E. HOLZ, 91 P. HOPKINS, 36 C. HORST, 21 J. HOUGH, 46 E. A. HOUSTON, 46 E. J. HOWELL, 64 A. HREIBI, 66 Y. M. HU, 10 E. A. HUERTA, 12 D. HUET, 28 B. HUGHEY, 37 S. HUSA, 102 S. H. HUTTNER, 46 T. HUYNH-DINH, 7 N. INDIK, 10 R. INTA, 83 G. INTINI, 97, 35 H. N. ISA, 46 J.-M. ISAC, 70 M. ISI, 1 B. R. IYER, 20 K. IZUMI, 47 T. JACQMIN, 70 K. JANI, 76 P. JARANOWSKI, 125 S. JAWAHAR, 62 F. JIM'ENEZ-FORTEZA, 102 W. W. JOHNSON, 2 D. I. JONES, 126 R. JONES, 46 R. J. G. JONKER, 14 L. JU, 64 J. JUNKER, 10 C. V. KALAGHATGI, 36 V. KALOGERA, 89 B. KAMAI, 1 S. KANDHASAMY, 7 G. KANG, 40 J. B. KANNER, 1 S. J. KAPADIA, 21 S. KARKI, 69 K. S. KARVINEN, 10 M. KASPRZACK, 2 M. KATOLIK, 12 E. KATSAVOUNIDIS, 15 W. KATZMAN, 7 S. KAUFER, 22 K. KAWABE, 47 F. K'EF'ELIAN, 66 D. KEITEL, 46 A. J. KEMBALL, 12 R. KENNEDY, 106 C. KENT, 36 J. S. KEY, 127 F. Y. KHALILI, 61 I. KHAN, 17, 33 S. KHAN, 10 Z. KHAN, 105 E. A. KHAZANOV, 128 N. KIJBUNCHOO, 25 CHUNGLEE KIM, 129 J. C. KIM, 130 K. KIM, 93 W. KIM, 72 W. S. KIM, 131 Y.-M. KIM, 92 S. J. KIMBRELL, 76 E. J. KING, 72 P. J. KING, 47 M. KINLEY-HANLON, 124 R. KIRCHHOFF, 10 J. S. KISSEL, 47 L. KLEYBOLTE, 34 S. KLIMENKO, 5 T. D. KNOWLES, 41 P. KOCH, 10 S. M. KOEHLENBECK, 10 S. KOLEY, 14 V. KONDRASHOV, 1 A. KONTOS, 15 M. KOROBKO, 34 W. Z. KORTH, 1 I. KOWALSKA, 73 D. B. KOZAK, 1 C. KR AMER, 10 V. KRINGEL, 10 B. KRISHNAN, 10 A. KR'OLAK, 132, 133 G. KUEHN, 10 P. KUMAR, 90 R. KUMAR, 105 S. KUMAR, 20 L. KUO, 87 A. KUTYNIA, 132 S. KWANG, 21 B. D. LACKEY, 38 K. H. LAI, 93 M. LANDRY, 47 R. N. LANG, 134 J. LANGE, 57 B. LANTZ, 51 R. K. LANZA, 15 A. LARTAUX-VOLLARD, 28 P. D. LASKY, 6 M. LAXEN, 7 A. LAZZARINI, 1  \nC. LAZZARO, 54 P. LEACI, 97, 35 S. LEAVEY, 46 C. H. LEE, 92 H. K. LEE, 135 H. M. LEE, 136 H. W. LEE, 130 K. LEE, 46 J. LEHMANN, 10 A. LENON, 41 M. LEONARDI, 110, 95 N. LEROY, 28 N. LETENDRE, 8 Y. LEVIN, 6 T. G. F. LI, 93 S. D. LINKER, 109 T. B. LITTENBERG, 137 J. LIU, 64 X. LIU, 21 R. K. L. LO, 93 N. A. LOCKERBIE, 62 L. T. LONDON, 36 J. E. LORD, 44 M. LORENZINI, 17, 18 V. LORIETTE, 138 M. LORMAND, 7 G. LOSURDO, 24 J. D. LOUGH, 10 C. O. LOUSTO, 57 G. LOVELACE, 29 H. L UCK, 22, 10 D. LUMACA, 32, 33 A. P. LUNDGREN, 10 R. LYNCH, 15 Y. MA, 48 R. MACAS, 36 S. MACFOY, 27 B. MACHENSCHALK, 10 M. MACINNIS, 15 D. M. MACLEOD, 36 I. MAGA˜NA HERNANDEZ, 21 F. MAGA˜NA-SANDOVAL, 44 L. MAGA˜NA ZERTUCHE, 44 R. M. MAGEE, 63 E. MAJORANA, 35 I. MAKSIMOVIC, 138 N. MAN, 66 V. MANDIC, 45 V. MANGANO, 46 G. L. MANSELL, 25 M. MANSKE, 21, 25 M. MANTOVANI, 30 F. MARCHESONI, 52, 43 F. MARION, 8 S. M 'ARKA, 50 Z. M'ARKA, 50 C. MARKAKIS, 12 A. S. MARKOSYAN, 51 A. MARKOWITZ, 1 E. MAROS, 1 A. MARQUINA, 100 F. MARTELLI, 121, 122 L. MARTELLINI, 66 I. W. MARTIN, 46 R. M. MARTIN, 111 D. V. MARTYNOV, 15 K. MASON, 15 E. MASSERA, 106 A. MASSEROT, 8 T. J. MASSINGER, 1 M. MASSO-REID, 46 S. MASTROGIOVANNI, 97, 35 A. MATAS, 45 F. MATICHARD, 1, 15 L. MATONE, 50 N. MAVALVALA, 15 N. MAZUMDER, 68 R. MCCARTHY, 47 D. E. MCCLELLAND, 25 S. MCCORMICK, 7 L. MCCULLER, 15 S. C. MCGUIRE, 139 G. MCINTYRE, 1 J. MCIVER, 1 D. J. MCMANUS, 25 L. MCNEILL, 6 T. MCRAE, 25 S. T. MCWILLIAMS, 41 D. MEACHER, 63 G. D. MEADORS, 38, 10 M. MEHMET, 10 J. MEIDAM, 14 E. MEJUTO-VILLA, 9 A. MELATOS, 96 G. MENDELL, 47 R. A. MERCER, 21 E. L. MERILH, 47 M. MERZOUGUI, 66 S. MESHKOV, 1 C. MESSENGER, 46 C. MESSICK, 63 R. METZDORFF, 70 P. M. MEYERS, 45 H. MIAO, 58 C. MICHEL, 26 H. MIDDLETON, 58 E. E. MIKHAILOV, 140 L. MILANO, 78, 4 A. L. MILLER, 5, 97, 35 B. B. MILLER, 89 J. MILLER, 15 M. MILLHOUSE, 101 M. C. MILOVICH-GOFF, 109 O. MINAZZOLI, 66, 141 Y. MINENKOV, 33 J. MING, 38 C. MISHRA, 142 S. MITRA, 19 V. P. MITROFANOV, 61 G. MITSELMAKHER, 5 R. MITTLEMAN, 15 D. MOFFA, 84 A. MOGGI, 24 K. MOGUSHI, 11 M. MOHAN, 30 S. R. P. MOHAPATRA, 15 M. MONTANI, 121, 122 C. J. MOORE, 13 D. MORARU, 47 G. MORENO, 47 S. R. MORRISS, 103 B. MOURS, 8 C. M. MOW-LOWRY, 58 G. MUELLER, 5 A. W. MUIR, 36 ARUNAVA MUKHERJEE, 10 D. MUKHERJEE, 21 S. MUKHERJEE, 103 N. MUKUND, 19 A. MULLAVEY, 7 J. MUNCH, 72 E. A. MU ˜NIZ, 44 M. MURATORE, 37 P. G. MURRAY, 46 K. NAPIER, 76 I. NARDECCHIA, 32, 33 L. NATICCHIONI, 97, 35 R. K. NAYAK, 143 J. NEILSON, 109 G. NELEMANS, 65, 14 T. J. N. NELSON, 7 M. NERY, 10 A. NEUNZERT, 118 L. NEVIN, 1 J. M. NEWPORT, 124 G. NEWTON, 46, † K. K. Y. NG, 93 T. T. NGUYEN, 25 D. NICHOLS, 65 A. B. NIELSEN, 10 S. NISSANKE, 65, 14 A. NITZ, 10 A. NOACK, 10 F. NOCERA, 30 D. NOLTING, 7 C. NORTH, 36 L. K. NUTTALL, 36 J. OBERLING, 47 G. D. O'DEA, 109 G. H. OGIN, 144 J. J. OH, 131 S. H. OH, 131 F. OHME, 10 M. A. OKADA, 16 M. OLIVER, 102 P. OPPERMANN, 10 RICHARD J. ORAM, 7 B. O'REILLY, 7 R. ORMISTON, 45 L. F. ORTEGA, 5 R. O'SHAUGHNESSY, 57 S. OSSOKINE, 38 D. J. OTTAWAY, 72 H. OVERMIER, 7 B. J. OWEN, 83 A. E. PACE, 63 J. PAGE, 137 M. A. PAGE, 64 A. PAI, 116, 145 S. A. PAI, 60 J. R. PALAMOS, 69 O. PALASHOV, 128 C. PALOMBA, 35 A. PAL-SINGH, 34 HOWARD PAN, 87 HUANG-WEI PAN, 87 B. PANG, 48 P. T. H. PANG, 93 C. PANKOW, 89 F. PANNARALE, 36 B. C. PANT, 60 F. PAOLETTI, 24 A. PAOLI, 30 M. A. PAPA, 38, 21, 10 A. PARIDA, 19 W. PARKER, 7 D. PASCUCCI, 46 A. PASQUALETTI, 30 R. PASSAQUIETI, 23, 24 D. PASSUELLO, 24 M. PATIL, 133 B. PATRICELLI, 146, 24 B. L. PEARLSTONE, 46 M. PEDRAZA, 1 R. PEDURAND, 26, 147 L. PEKOWSKY, 44 A. PELE, 7 S. PENN, 148 C. J. PEREZ, 47 A. PERRECA, 1, 110, 95 L. M. PERRI, 89 H. P. PFEIFFER, 90, 38 M. PHELPS, 46 O. J. PICCINNI, 97, 35 M. PICHOT, 66 F. PIERGIOVANNI, 121, 122 V. PIERRO, 9 G. PILLANT, 30 L. PINARD, 26 I. M. PINTO, 9 M. PIRELLO, 47 M. PITKIN, 46 M. POE, 21 R. POGGIANI, 23, 24 P. POPOLIZIO, 30 E. K. PORTER, 39 A. POST, 10 J. POWELL, 46, 149 J. PRASAD, 19 J. W. W. PRATT, 37 G. PRATTEN, 102 V. PREDOI, 36 T. PRESTEGARD, 21 M. PRIJATELJ, 10 M. PRINCIPE, 9 S. PRIVITERA, 38 G. A. PRODI, 110, 95 L. G. PROKHOROV, 61 O. PUNCKEN, 10 M. PUNTURO, 43 P. PUPPO, 35 M. P URRER, 38 H. QI, 21 V. QUETSCHKE, 103 E. A. QUINTERO, 1 R. QUITZOW-JAMES, 69 F. J. RAAB, 47 D. S. RABELING, 25 H. RADKINS, 47 P. RAFFAI, 55 S. RAJA, 60 C. RAJAN, 60 B. RAJBHANDARI, 83 M. RAKHMANOV, 103 K. E. RAMIREZ, 103 A. RAMOS-BUADES, 102 P. RAPAGNANI, 97, 35 V. RAYMOND, 38 M. RAZZANO, 23, 24 J. READ, 29 T. REGIMBAU, 66 L. REI, 59 S. REID, 62 D. H. REITZE, 1, 5 W. REN, 12 S. D. REYES, 44 F. RICCI, 97, 35 P. M. RICKER, 12 S. RIEGER, 10 K. RILES, 118 M. RIZZO, 57 N. A. ROBERTSON, 1, 46 R. ROBIE, 46 F. ROBINET, 28 A. ROCCHI, 33 L. ROLLAND, 8  \nJ. G. ROLLINS, 1 V. J. ROMA, 69 J. D. ROMANO, 103 R. ROMANO, 3, 4 C. L. ROMEL, 47 J. H. ROMIE, 7 D. ROSI 'NSKA, 150, 56 M. P. ROSS, 151 S. ROWAN, 46 A. R UDIGER, 10 P. RUGGI, 30 G. RUTINS, 27 K. RYAN, 47 S. SACHDEV, 1 T. SADECKI, 47 L. SADEGHIAN, 21 M. SAKELLARIADOU, 152 L. SALCONI, 30 M. SALEEM, 116 F. SALEMI, 10 A. SAMAJDAR, 143 L. SAMMUT, 6 L. M. SAMPSON, 89 E. J. SANCHEZ, 1 L. E. SANCHEZ, 1 N. SANCHIS-GUAL, 85 V. SANDBERG, 47 J. R. SANDERS, 44 B. SASSOLAS, 26 B. S. SATHYAPRAKASH, 63, 36 P. R. SAULSON, 44 O. SAUTER, 118 R. L. SAVAGE, 47 A. SAWADSKY, 34 P. SCHALE, 69 M. SCHEEL, 48 J. SCHEUER, 89 J. SCHMIDT, 10 P. SCHMIDT, 1, 65 R. SCHNABEL, 34 R. M. S. SCHOFIELD, 69 A. SCH ONBECK, 34 E. SCHREIBER, 10 D. SCHUETTE, 10, 22 B. W. SCHULTE, 10 B. F. SCHUTZ, 36, 10 S. G. SCHWALBE, 37 J. SCOTT, 46 S. M. SCOTT, 25 E. SEIDEL, 12 D. SELLERS, 7 A. S. SENGUPTA, 153 D. SENTENAC, 30 V. SEQUINO, 32, 33, 17 A. SERGEEV, 128 D. A. SHADDOCK, 25 T. J. SHAFFER, 47 A. A. SHAH, 137 M. S. SHAHRIAR, 89 M. B. SHANER, 109 L. SHAO, 38 B. SHAPIRO, 51 P. SHAWHAN, 75 A. SHEPERD, 21 D. H. SHOEMAKER, 15 D. M. SHOEMAKER, 76 K. SIELLEZ, 76 X. SIEMENS, 21 M. SIENIAWSKA, 56 D. SIGG, 47 A. D. SILVA, 16 L. P. SINGER, 79 A. SINGH, 38, 10, 22 A. SINGHAL, 17, 35 A. M. SINTES, 102 B. J. J. SLAGMOLEN, 25 B. SMITH, 7 J. R. SMITH, 29 R. J. E. SMITH, 1, 6 S. SOMALA, 154 E. J. SON, 131 J. A. SONNENBERG, 21 B. SORAZU, 46 F. SORRENTINO, 59 T. SOURADEEP, 19 A. P. SPENCER, 46 A. K. SRIVASTAVA, 105 K. STAATS, 37 A. STALEY, 50 D. STEER, 39 M. STEINKE, 10 J. STEINLECHNER, 34, 46 S. STEINLECHNER, 34 D. STEINMEYER, 10 S. P. STEVENSON, 58, 149 R. STONE, 103 D. J. STOPS, 58 K. A. STRAIN, 46 G. STRATTA, 121, 122 S. E. STRIGIN, 61 A. STRUNK, 47 R. STURANI, 155 A. L. STUVER, 7 T. Z. SUMMERSCALES, 156 L. SUN, 96 S. SUNIL, 105 J. SURESH, 19 P. J. SUTTON, 36 B. L. SWINKELS, 30 M. J. SZCZEPA 'NCZYK, 37 M. TACCA, 14 S. C. TAIT, 46 C. TALBOT, 6 D. TALUKDER, 69 D. B. TANNER, 5 M. T'APAI, 117 A. TARACCHINI, 38 J. D. TASSON, 71 J. A. TAYLOR, 137 R. TAYLOR, 1 S. V. TEWARI, 148 T. THEEG, 10 F. THIES, 10 E. G. THOMAS, 58 M. THOMAS, 7 P. THOMAS, 47 K. A. THORNE, 7 E. THRANE, 6 S. TIWARI, 17, 95 V. TIWARI, 36 K. V. TOKMAKOV, 62 K. TOLAND, 46 M. TONELLI, 23, 24 Z. TORNASI, 46 A. TORRES-FORN'E, 85 C. I. TORRIE, 1 D. T OYR A, 58 F. TRAVASSO, 30, 43 G. TRAYLOR, 7 J. TRINASTIC, 5 M. C. TRINGALI, 110, 95 L. TROZZO, 157, 24 K. W. TSANG, 14 M. TSE, 15 R. TSO, 1 L. TSUKADA, 81 D. TSUNA, 81 D. TUYENBAYEV, 103 K. UENO, 21 D. UGOLINI, 158 C. S. UNNIKRISHNAN, 119 A. L. URBAN, 1 S. A. USMAN, 36 H. VAHLBRUCH, 22 G. VAJENTE, 1 G. VALDES, 2 N. VAN BAKEL, 14 M. VAN BEUZEKOM, 14 J. F. J. VAN DEN BRAND, 74, 14 C. VAN DEN BROECK, 14 D. C. VANDER-HYDE, 44 L. VAN DER SCHAAF, 14 J. V. VAN HEIJNINGEN, 14 A. A. VAN VEGGEL, 46 M. VARDARO, 53, 54 V. VARMA, 48 S. VASS, 1 M. VAS'UTH, 49 A. VECCHIO, 58 G. VEDOVATO, 54 J. VEITCH, 46 P. J. VEITCH, 72 K. VENKATESWARA, 151 G. VENUGOPALAN, 1 D. VERKINDT, 8 F. VETRANO, 121, 122 A. VICER'E, 121, 122 A. D. VIETS, 21 S. VINCIGUERRA, 58 D. J. VINE, 27 J.-Y. VINET, 66 S. VITALE, 15 T. VO, 44 H. VOCCA, 42, 43 C. VORVICK, 47 S. P. VYATCHANIN, 61 A. R. WADE, 1 L. E. WADE, 84 M. WADE, 84 R. WALET, 14 M. WALKER, 29 L. WALLACE, 1 S. WALSH, 38, 10, 21 G. WANG, 17, 122 H. WANG, 58 J. Z. WANG, 63 W. H. WANG, 103 Y. F. WANG, 93 R. L. WARD, 25 J. WARNER, 47 M. WAS, 8 J. WATCHI, 98 B. WEAVER, 47 L.-W. WEI, 10, 22 M. WEINERT, 10 A. J. WEINSTEIN, 1 R. WEISS, 15 L. WEN, 64 E. K. WESSEL, 12 P. WESSELS, 10 J. WESTERWECK, 10 T. WESTPHAL, 10 K. WETTE, 25 J. T. WHELAN, 57 S. E. WHITCOMB, 1 B. F. WHITING, 5 C. WHITTLE, 6 D. WILKEN, 10 D. WILLIAMS, 46 R. D. WILLIAMS, 1 A. R. WILLIAMSON, 65 J. L. WILLIS, 1, 159 B. WILLKE, 22, 10 M. H. WIMMER, 10 W. WINKLER, 10 C. C. WIPF, 1 H. WITTEL, 10, 22 G. WOAN, 46 J. WOEHLER, 10 J. WOFFORD, 57 K. W. K. WONG, 93 J. WORDEN, 47 J. L. WRIGHT, 46 D. S. WU, 10 D. M. WYSOCKI, 57 S. XIAO, 1 H. YAMAMOTO, 1 C. C. YANCEY, 75 L. YANG, 160 M. J. YAP, 25 M. YAZBACK, 5 HANG YU, 15 HAOCUN YU, 15 M. YVERT, 8 A. ZADRO˙ZNY, 132 M. ZANOLIN, 37 T. ZELENOVA, 30 J.-P. ZENDRI, 54 M. ZEVIN, 89 L. ZHANG, 1 M. ZHANG, 140 T. ZHANG, 46 Y.-H. ZHANG, 57 C. ZHAO, 64 M. ZHOU, 89 Z. ZHOU, 89 S. J. ZHU, 38, 10 X. J. ZHU, 6 A. B. ZIMMERMAN, 90 M. E. ZUCKER, 1, 15 AND J. ZWEIZIG 1  \nTHE LIGO SCIENTIFIC COLLABORATION AND THE VIRGO COLLABORATION  \nR. J. FOLEY, 161 D. A. COULTER, 161 M. R. DROUT, 162, 163 D. KASEN, 164, 165 C. D. KILPATRICK, 161 B. F. MADORE, 162 A. MURGUIA-BERTHIER, 161 Y.-C. PAN, 161 A. L. PIRO, 162 J. X. PROCHASKA, 161  \n- E. RAMIREZ-RUIZ, 161, 166 A. REST, 167 C. ROJAS-BRAVO, 161 B. J. SHAPPEE, 162, 168, 169 M. R. SIEBERT, 161 J. D. SIMON, 162 AND N. ULLOA 170", 'THE 1M2H COLLABORATION': "J. ANNIS, 171 M. SOARES-SANTOS, 172, 171 D. BROUT, 173 D. SCOLNIC, 174 H. T. DIEHL, 171, 171 J. FRIEMAN, 171, 174 E. BERGER, 175 K. D. ALEXANDER, 175 S. ALLAM, 171, 171 E. BALBINOT, 176 P. BLANCHARD, 177 R. E. BUTLER, 178, 171 R. CHORNOCK, 179 E. R. COOK, 180, 181 P. COWPERTHWAITE, 175 A. DRLICA-WAGNER, 171, 171 M. R. DROUT, 163, 182 F. DURRET, 183 T. EFTEKHARI, 177 D. A. FINLEY, 171 W. FONG, 184, 185 C. L. FRYER, 186 J. GARC'IA-BELLIDO, 187 M. S .S. GILL, 188 R. A. GRUENDL, 189, 190 C. HANNA, 191, 190 W. HARTLEY, 192, 193 K. HERNER, 171 D. HUTERER, 194 D. KASEN, 195 R. KESSLER, 174 T. S. LI, 171 H. LIN, 171, 171 P. A. A. LOPES, 196 A. C. C. LOURENC¸O, 196 R. MARGUTTI, 197 J. MARRINER, 171 J. L. MARSHALL, 180, 198 T. MATHESON, 199 G. E. MEDINA, 200 B. D. METZGER, 201 R. R. MU ˜NOZ, 200 J. MUIR, 202 M. NICHOLL, 175 P. NUGENT, 203 A. PALMESE, 192 F. PAZ-CHINCH 'ON, 190, 190 E. QUATAERT, 204 M. SAKO, 173 M. SAUSEDA, 180 D. J. SCHLEGEL, 205 L. F. SECCO, 173 N. SMITH, 206 F. SOBREIRA, 207, 208, 207, 208 A. STEBBINS, 171 V. A. VILLAR, 177 A. K. VIVAS, 209 W. WESTER, 171 P. K. G. WILLIAMS, 177 B. YANNY, 171 A. ZENTENO, 209 T. M. C. ABBOTT, 209 F. B. ABDALLA, 192, 210 K. BECHTOL, 181 A. BENOIT-L'EVY, 211, 192, 212 E. BERTIN, 211, 212 S. L. BRIDLE, 213 D. BROOKS, 192 E. BUCKLEY-GEER, 171 D. L. BURKE, 214, 188 A. CARNERO ROSELL, 208, 215 M. CARRASCO KIND, 189, 190 J. CARRETERO, 216 F. J. CASTANDER, 217 C. E. CUNHA, 214 C. B. D'ANDREA, 173 L. N. DA COSTA, 208, 215 C. DAVIS, 214 D. L. DEPOY, 198 S. DESAI, 218 J. P. DIETRICH, 219, 220 J. ESTRADA, 171 E. FERNANDEZ, 216 B. FLAUGHER, 171 P. FOSALBA, 217 E. GAZTANAGA, 217 D. W. GERDES, 221, 194 T. GIANNANTONIO, 222, 223, 224 D. A. GOLDSTEIN, 225, 203 D. GRUEN, 214, 188 G. GUTIERREZ, 171 W. G. HARTLEY, 192, 193 K. HONSCHEID, 226, 227 B. JAIN, 173 D. J. JAMES, 228 T. JELTEMA, 229 M. W. G. JOHNSON, 190 S. KENT, 171, 174 E. KRAUSE, 214 R. KRON, 171, 174 K. KUEHN, 230 S. KUHLMANN, 231 N. KUROPATKIN, 171 O. LAHAV, 192 M. LIMA, 232, 208 M. A. G. MAIA, 208, 215 M. MARCH, 173 C. J. MILLER, 221, 194 R. MIQUEL, 233, 216 E. NEILSEN, 171 B. NORD, 171 R. L. C. OGANDO, 208, 215 A. A. PLAZAS, 234 A. K. ROMER, 235 A. ROODMAN, 214, 188 E. S. RYKOFF, 214, 188 E. SANCHEZ, 236 V. SCARPINE, 171 M. SCHUBNELL, 194 I. SEVILLA-NOARBE, 236 M. SMITH, 237 R. C. SMITH, 209 E. SUCHYTA, 238 G. TARLE, 194 D. THOMAS, 239 R. C. THOMAS, 203 M. A. TROXEL, 226, 227 D. L. TUCKER, 171 V. VIKRAM, 231 A. R. WALKER, 209 J. WELLER, 219, 240, 224 AND Y. ZHANG 171  \nTHE DARK ENERGY CAMERA GW-EM COLLABORATION AND THE DES COLLABORATION  \nJ. B. HAISLIP,  \n241  \nV. V. KOUPRIANOV,  \n241  \nD. E. REICHART,  \nS. VALENTI,  \n243  \n241  \nAND S. YANG  \nL. TARTAGLIA,  \n243, 244, 245", 'THE DLT40 COLLABORATION': "IAIR ARCAVI, 246, 247 GRIFFIN HOSSEINZADEH, 246, 247 D. ANDREW HOWELL, 246, 247 CURTIS MCCULLY, 246, 247 DOVI POZNANSKI, 248 AND SERGIY VASYLYEV 246, 247 THE LAS CUMBRES OBSERVATORY COLLABORATION  \nN. R. TANVIR, 249 A. J. LEVAN, 250 J. HJORTH, 251 Z. CANO, 252 C. COPPERWHEAT, 253 A. DE UGARTE-POSTIGO, 252 P.A. EVANS, 249 J.P.U. FYNBO, 251 C. GONZ'ALEZ-FERN 'ANDEZ, 254 J. GREINER, 255 M. IRWIN, 254 J. LYMAN, 250 I. MANDEL, 256 R. MCMAHON, 254 B. MILVANG-JENSEN, 251 P. O'BRIEN, 249 J. P. OSBORNE, 249 D. A. PERLEY, 253 E. PIAN, 257 E. PALAZZI, 257 E. ROL, 258 S. ROSETTI, 249 S. ROSSWOG, 259 A. ROWLINSON, 260, 261 S. SCHULZE, 262 D.T.H. STEEGHS, 250 C.C. TH ONE, 252 K. ULACZYK, 250 D. WATSON, 251 AND K. WIERSEMA 249, 250", 'THE VINROUGE COLLABORATION': 'V.M. LIPUNOV, 263, 264 E. GORBOVSKOY, 264 V.G. KORNILOV, 263, 264 N .TYURINA, 264 P. BALANUTSA, 264 D.VLASENKO, 263, 264 I.GORBUNOV, 264 R. PODESTA, 265 H. LEVATO, 266 C. SAFFE, 266 D.A.H.BUCKLEY, 267 N.M. BUDNEV, 268 O. GRESS, 268, 264 V. YURKOV, 269 R. REBOLO, 270 AND M. SERRA-RICART 270  \n242, 243  \nD. J. SAND,  \n242', 'THE MASTER COLLABORATION': "- 1 LIGO, California Institute of Technology, Pasadena, CA 91125, USA\n- 2 Louisiana State University, Baton Rouge, LA 70803, USA\n- 3 Universit'a di Salerno, Fisciano, I-84084 Salerno, Italy\n- 4 INFN, Sezione di Napoli, Complesso Universitario di Monte S.Angelo, I-80126 Napoli, Italy\n- 5 University of Florida, Gainesville, FL 32611, USA\n- 6 OzGrav, School of Physics & Astronomy, Monash University, Clayton 3800, Victoria, Australia\n- 7 LIGO Livingston Observatory, Livingston, LA 70754, USA\n- 8 Laboratoire d'Annecy-le-Vieux de Physique des Particules (LAPP), Universit'e Savoie Mont Blanc, CNRS/IN2P3, F-74941 Annecy, France\n- 9 University of Sannio at Benevento, I-82100 Benevento, Italy and INFN, Sezione di Napoli, I-80100 Napoli, Italy\n- 10 Max Planck Institute for Gravitational Physics (Albert Einstein Institute), D-30167 Hannover, Germany\n- 11 The University of Mississippi, University, MS 38677, USA\n- 12 NCSA, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA\n- 13 University of Cambridge, Cambridge CB2 1TN, United Kingdom\n- 14 Nikhef, Science Park, 1098 XG Amsterdam, The Netherlands\n- 15 LIGO, Massachusetts Institute of Technology, Cambridge, MA 02139, USA\n- 16 Instituto Nacional de Pesquisas Espaciais, 12227-010 S˜ao Jos'e dos Campos, S˜ao Paulo, Brazil\n- 17 Gran Sasso Science Institute (GSSI), I-67100 L'Aquila, Italy\n- 18 INFN, Laboratori Nazionali del Gran Sasso, I-67100 Assergi, Italy\n- 19 Inter-University Centre for Astronomy and Astrophysics, Pune 411007, India\n- 20 International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, Bengaluru 560089, India\n- 21 University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA\n- 22 Leibniz Universitat Hannover, D-30167 Hannover, Germany\n- 23 Universit'a di Pisa, I-56127 Pisa, Italy\n- 24 INFN, Sezione di Pisa, I-56127 Pisa, Italy\n- 25 OzGrav, Australian National University, Canberra, Australian Capital Territory 0200, Australia\n- 26 Laboratoire des Mat'eriaux Avanc'es (LMA), CNRS/IN2P3, F-69622 Villeurbanne, France\n- 27 SUPA, University of the West of Scotland, Paisley PA1 2BE, United Kingdom\n- 28 LAL, Univ. Paris-Sud, CNRS/IN2P3, Universit'e Paris-Saclay, F-91898 Orsay, France\n- 29 California State University Fullerton, Fullerton, CA 92831, USA\n- 30 European Gravitational Observatory (EGO), I-56021 Cascina, Pisa, Italy\n- 31\n- Chennai Mathematical Institute, Chennai 603103, India\n- 32 Universit'a di Roma Tor Vergata, I-00133 Roma, Italy\n- 33 INFN, Sezione di Roma Tor Vergata, I-00133 Roma, Italy\n- 34 Universitat Hamburg, D-22761 Hamburg, Germany\n- 35 INFN, Sezione di Roma, I-00185 Roma, Italy\n- 36 Cardiff University, Cardiff CF24 3AA, United Kingdom\n- 37 Embry-Riddle Aeronautical University, Prescott, AZ 86301, USA\n- 38 Max Planck Institute for Gravitational Physics (Albert Einstein Institute), D-14476 Potsdam-Golm, Germany\n- 39 APC, AstroParticule et Cosmologie, Universit'e Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cit'e, F-75205 Paris Cedex 13, France\n- 40 Korea Institute of Science and Technology Information, Daejeon 34141, Korea\n- 41 West Virginia University, Morgantown, WV 26506, USA\n- 42 Universit'a di Perugia, I-06123 Perugia, Italy\n- 43 INFN, Sezione di Perugia, I-06123 Perugia, Italy\n- 44 Syracuse University, Syracuse, NY 13244, USA\n- 45 University of Minnesota, Minneapolis, MN 55455, USA\n- 46 SUPA, University of Glasgow, Glasgow G12 8QQ, United Kingdom\n- 47 LIGO Hanford Observatory, Richland, WA 99352, USA\n- 48 Caltech CaRT, Pasadena, CA 91125, USA  \n- 49 Wigner RCP, RMKI, H-1121 Budapest, Konkoly Thege Mikl'os 'ut 29-33, Hungary\n- 50 Columbia University, New York, NY 10027, USA\n- 51 Stanford University, Stanford, CA 94305, USA\n- 52 Universit'a di Camerino, Dipartimento di Fisica, I-62032 Camerino, Italy\n- 53 Universit'a di Padova, Dipartimento di Fisica e Astronomia, I-35131 Padova, Italy\n- 54 INFN, Sezione di Padova, I-35131 Padova, Italy\n- 55 Institute of Physics, Eotvos University, P'azm'any P. s. 1/A, Budapest 1117, Hungary\n- 56 Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, 00-716, Warsaw, Poland\n- 57 Rochester Institute of Technology, Rochester, NY 14623, USA\n- 58 University of Birmingham, Birmingham B15 2TT, United Kingdom\n- 59 INFN, Sezione di Genova, I-16146 Genova, Italy\n- 60 RRCAT, Indore MP 452013, India\n- 61 Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia\n- 62 SUPA, University of Strathclyde, Glasgow G1 1XQ, United Kingdom\n- 63 The Pennsylvania State University, University Park, PA 16802, USA\n- 64 OzGrav, University of Western Australia, Crawley, Western Australia 6009, Australia\n- 65 Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands\n- 66 Artemis, Universit'e Cˆote d'Azur, Observatoire Cˆote d'Azur, CNRS, CS 34229, F-06304 Nice Cedex 4, France\n- 67 Institut FOTON, CNRS, Universit'e de Rennes 1, F-35042 Rennes, France\n- 68 Washington State University, Pullman, WA 99164, USA\n- 69 University of Oregon, Eugene, OR 97403, USA\n- 70 Laboratoire Kastler Brossel, UPMC-Sorbonne Universit'es, CNRS, ENS-PSL Research University, Coll'ege de France, F-75005 Paris, France\n- 71 Carleton College, Northfield, MN 55057, USA\n- 72 OzGrav, University of Adelaide, Adelaide, South Australia 5005, Australia\n- 73 Astronomical Observatory Warsaw University, 00-478 Warsaw, Poland\n- 74 VU University Amsterdam, 1081 HV Amsterdam, The Netherlands\n- 75 University of Maryland, College Park, MD 20742, USA\n- 76 Center for Relativistic Astrophysics, Georgia Institute of Technology, Atlanta, GA 30332, USA\n- 77 Universit'e Claude Bernard Lyon 1, F-69622 Villeurbanne, France\n- 78 Universit'a di Napoli 'Federico II,' Complesso Universitario di Monte S.Angelo, I-80126 Napoli, Italy\n- 79 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA\n- 80 Dipartimento di Fisica, Universit'a degli Studi di Genova, I-16146 Genova, Italy\n- 81 RESCEU, University of Tokyo, Tokyo, 113-0033, Japan.\n- 82 Tsinghua University, Beijing 100084, China\n- 83 Texas Tech University, Lubbock, TX 79409, USA\n- 84 Kenyon College, Gambier, OH 43022, USA\n- 85 Departamento de Astronom'ıa y Astrof'ısica, Universitat de Val'encia, E-46100 Burjassot, Val'encia, Spain\n- 86 Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, I-00184 Roma, Italy\n- 87 National Tsing Hua University, Hsinchu City, 30013 Taiwan, Republic of China\n- 88 Charles Sturt University, Wagga Wagga, New South Wales 2678, Australia\n- 89 Center for Interdisciplinary Exploration & Research in Astrophysics (CIERA), Northwestern University, Evanston, IL 60208, USA\n- 90 Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, Ontario M5S 3H8, Canada\n- 91 University of Chicago, Chicago, IL 60637, USA\n- 92 Pusan National University, Busan 46241, Korea\n- 93 The Chinese University of Hong Kong, Shatin, NT, Hong Kong\n- 94 INAF, Osservatorio Astronomico di Padova, I-35122 Padova, Italy\n- 95 INFN, Trento Institute for Fundamental Physics and Applications, I-38123 Povo, Trento, Italy\n- 96 OzGrav, University of Melbourne, Parkville, Victoria 3010, Australia\n- 97 Universit'a di Roma 'La Sapienza,' I-00185 Roma, Italy\n- 98 Universit'e Libre de Bruxelles, Brussels 1050, Belgium\n- 99 Sonoma State University, Rohnert Park, CA 94928, USA\n- 100 Departamento de Matem'aticas, Universitat de Val'encia, E-46100 Burjassot, Val'encia, Spain\n- 101 Montana State University, Bozeman, MT 59717, USA\n- 102 Universitat de les Illes Balears, IAC3-IEEC, E-07122 Palma de Mallorca, Spain\n- 103 The University of Texas Rio Grande Valley, Brownsville, TX 78520, USA\n- 104 Bellevue College, Bellevue, WA 98007, USA\n- 105 Institute for Plasma Research, Bhat, Gandhinagar 382428, India\n- 106 The University of Sheffield, Sheffield S10 2TN, United Kingdom\n- 107 Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Universit'a di Parma, I-43124 Parma, Italy\n- 108 INFN, Sezione di Milano Bicocca, Gruppo Collegato di Parma, I-43124 Parma, Italy\n- 109 California State University, Los Angeles, 5151 State University Dr, Los Angeles, CA 90032, USA\n- 110 Universit'a di Trento, Dipartimento di Fisica, I-38123 Povo, Trento, Italy\n- 111 Montclair State University, Montclair, NJ 07043, USA\n- 112 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan\n- 113 Observatori Astron'omic, Universitat de Val'encia, E-46980 Paterna, Val'encia, Spain\n- 114 School of Mathematics, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom\n- 115 University and Institute of Advanced Research, Koba Institutional Area, Gandhinagar Gujarat 382007, India\n- 116 IISER-TVM, CET Campus, Trivandrum Kerala 695016, India\n- 117 University of Szeged, D'om t'er 9, Szeged 6720, Hungary\n- 118 University of Michigan, Ann Arbor, MI 48109, USA\n- 119 Tata Institute of Fundamental Research, Mumbai 400005, India\n- 120 INAF, Osservatorio Astronomico di Capodimonte, I-80131, Napoli, Italy\n- 121 Universit'a degli Studi di Urbino 'Carlo Bo,' I-61029 Urbino, Italy\n- 122 INFN, Sezione di Firenze, I-50019 Sesto Fiorentino, Firenze, Italy\n- 123 Physik-Institut, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland\n- 124 American University, Washington, D.C. 20016, USA\n- 125 University of Białystok, 15-424 Białystok, Poland\n- 126 University of Southampton, Southampton SO17 1BJ, United Kingdom\n- 127 University of Washington Bothell, 18115 Campus Way NE, Bothell, WA 98011, USA\n- 128 Institute of Applied Physics, Nizhny Novgorod, 603950, Russia\n- 129 Korea Astronomy and Space Science Institute, Daejeon 34055, Korea\n- 130 Inje University Gimhae, South Gyeongsang 50834, Korea\n- 131 National Institute for Mathematical Sciences, Daejeon 34047, Korea\n- 132 NCBJ, 05-400 ' Swierk-Otwock, Poland\n- 133 Institute of Mathematics, Polish Academy of Sciences, 00656 Warsaw, Poland\n- 134 Hillsdale College, Hillsdale, MI 49242, USA\n- 135 Hanyang University, Seoul 04763, Korea\n- 136 Seoul National University, Seoul 08826, Korea\n- 137 NASA Marshall Space Flight Center, Huntsville, AL 35811, USA\n- 138 ESPCI, CNRS, F-75005 Paris, France\n- 139 Southern University and A&M College, Baton Rouge, LA 70813, USA\n- 140 College of William and Mary, Williamsburg, VA 23187, USA\n- 141 Centre Scientifique de Monaco, 8 quai Antoine Ier, MC-98000, Monaco\n- 142 Indian Institute of Technology Madras, Chennai 600036, India\n- 143 IISER-Kolkata, Mohanpur, West Bengal 741252, India\n- 144 Whitman College, 345 Boyer Avenue, Walla Walla, WA 99362 USA\n- 145 Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra 400076, India\n- 146 Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy\n- 147 Universit'e de Lyon, F-69361 Lyon, France\n- 148 Hobart and William Smith Colleges, Geneva, NY 14456, USA\n- 149 OzGrav, Swinburne University of Technology, Hawthorn VIC 3122, Australia\n- 150 Janusz Gil Institute of Astronomy, University of Zielona G'ora, 65-265 Zielona G'ora, Poland\n- 151 University of Washington, Seattle, WA 98195, USA\n- 152 King's College London, University of London, London WC2R 2LS, United Kingdom\n- 153 Indian Institute of Technology, Gandhinagar Ahmedabad Gujarat 382424, India\n- 154 Indian Institute of Technology Hyderabad, Sangareddy, Khandi, Telangana 502285, India  \n- 155 International Institute of Physics, Universidade Federal do Rio Grande do Norte, Natal RN 59078-970, Brazil\n- 156 Andrews University, Berrien Springs, MI 49104, USA\n- 157 Universit'a di Siena, I-53100 Siena, Italy\n- 158 Trinity University, San Antonio, TX 78212, USA\n- 159 Abilene Christian University, Abilene, TX 79699, USA\n- 160 Colorado State University, Fort Collins, CO 80523, USA\n- 161 Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064, USA\n- 162 The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101\n- 163 Hubble and Carnegie-Dunlap Fellow\n- 164 Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA\n- 165 Departments of Physics and Astronomy, University of California, Berkeley, CA 94720, USA\n- 166 Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen, Denmark\n- 167 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218\n- 168\n- Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Drive, Honolulu, HI 96822, USA\n- 169 Hubble and Carnegie-Princeton Fellow\n- 170 Departamento de F'ısica y Astronom'ıa, Universidad de La Serena, La Serena, Chile\n- 171 Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, IL 60510, USA\n- 172 Department of Physics, Brandeis University, Waltham MA, USA\n- 173 Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA\n- 174 Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA\n- 175 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA\n- 176 Department of Physics, University of Surrey, Guildford, GU2 7XH, UK\n- 177 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA\n- 178 Department of Astronomy, Indiana University, 727 E. Third Street, Bloomington, IN 47405, USA\n- 179\n- 180\n- Astrophysical Institute, Department of Physics and Astronomy, 251B Clippinger Lab, Ohio University, Athens, OH 45701, USA\n- George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA\n- 181 LSST, 933 North Cherry Avenue, Tucson, AZ 85721, USA\n- 182 The Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101, USA\n- 183 Institut d'Astrophysique de Paris (UMR7095: CNRS & UPMC), 98 bis Bd Arago, F-75014, Paris, France\n- 184 Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA\n- 185 Hubble Fellow\n- 186 Center for Theoretical Astrophysics, Los Alamos National Laboratory, Los Alamos, NM 87544\n- 187\n- Instituto de Fisica Teorica UAM/CSIC, Universidad Autonoma de Madrid, 28049 Madrid, Spain\n- 188 SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA\n- 189 Department of Astronomy, University of Illinois, 1002 W. Green Street, Urbana, IL 61801, USA\n- 190 National Center for Supercomputing Applications, 1205 West Clark St., Urbana, IL 61801, USA\n- 191 Department of Physics and Astronomy & Astrophysics,The Pennsylvania State University, University Park, PA 16802, USA\n- 192 Department of Physics & Astronomy, University College London, Gower Street, London, WC1E 6BT, UK\n- 193 Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 16, CH-8093 Zurich, Switzerland\n- 194 Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA\n- 195 Departments of Physics and Astronomy, and Theoretical Astrophysics Center, University of California, Berkeley, CA 94720-7300, USA\n- 196 Observat'orio do Valongo, Universidade Federal do Rio de Janeiro, Ladeira do Pedro Antˆonio 43, Rio de Janeiro, RJ, 20080-090, Brazil\n- 197 Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208\n- 198 George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA\n- 199 National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719, USA\n- 200 Departamento de Astronomon'ıa, Universidad de Chile, Camino del Observatorio 1515, Las Condes, Santiago, Chile\n- 201 Department of Physics and Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA\n- 202 Department of Physics, University of Michigan, 450 Church St, Ann Arbor, MI 48109-1040\n- 203 Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA\n- 204 Department of Astronomy & Theoretical Astrophysics Center, University of California, Berkeley, CA 94720-3411, USA\n- 205 Physics Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8160, USA\n- 206 Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721\n- 207 Instituto de F'ısica Gleb Wataghin, Universidade Estadual de Campinas, 13083-859, Campinas, SP, Brazil\n- 208 Laborat'orio Interinstitucional de e-Astronomia - LIneA, Rua Gal. Jos'e Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil\n- 209 Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena, Chile\n- 210 Department of Physics and Electronics, Rhodes University, PO Box 94, Grahamstown, 6140, South Africa\n- 211 CNRS, UMR 7095, Institut d'Astrophysique de Paris, F-75014, Paris, France\n- 212 Sorbonne Universit'es, UPMC Univ Paris 06, UMR 7095, Institut d'Astrophysique de Paris, F-75014, Paris, France\n- 213 Jodrell Bank Center for Astrophysics, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL, UK\n- 214 Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, CA 94305, USA\n- 215 Observat'orio Nacional, Rua Gal. Jos'e Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil\n- 216 Institut de F'ısica d'Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona) Spain\n- 217 Institute of Space Sciences, IEEC-CSIC, Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain\n- 218 Department of Physics, IIT Hyderabad, Kandi, Telangana 502285, India\n- 219 Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany\n- 220 Faculty of Physics, Ludwig-Maximilians-Universitat, Scheinerstr. 1, 81679 Munich, Germany\n- 221\n- Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA\n- 222 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK\n- 223 Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK\n- 224 Universitats-Sternwarte, Fakultat fur Physik, Ludwig-Maximilians Universitat Munchen, Scheinerstr. 1, 81679 Munchen, Germany\n- 225 Department of Astronomy, University of California, Berkeley, 501 Campbell Hall, Berkeley, CA 94720, USA\n- 226 Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210, USA\n- 227 Department of Physics, The Ohio State University, Columbus, OH 43210, USA\n- 228 Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195, USA\n- 229 Santa Cruz Institute for Particle Physics, Santa Cruz, CA 95064, USA\n- 230 Australian Astronomical Observatory, North Ryde, NSW 2113, Australia\n- 231 Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439, USA\n- 232 Departamento de F'ısica Matem'atica, Instituto de F'ısica, Universidade de S˜ao Paulo, CP 66318, S˜ao Paulo, SP, 05314-970, Brazil\n- 233 Instituci'o Catalana de Recerca i Estudis Avanc¸ats, E-08010 Barcelona, Spain\n- 234 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, USA\n- 235 Department of Physics and Astronomy, Pevensey Building, University of Sussex, Brighton, BN1 9QH, UK\n- 236 Centro de Investigaciones Energ'eticas, Medioambientales y Tecnol'ogicas (CIEMAT), Madrid, Spain\n- 237 School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK\n- 238 Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831\n- 239 Institute of Cosmology & Gravitation, University of Portsmouth, Portsmouth, PO1 3FX, UK\n- 240 Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, 85748 Garching, Germany\n- 241 Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA\n- 242 Department of Astronomy and Steward Observatory, University of Arizona, 933 N Cherry Ave, Tucson, AZ 85719, USA\n- 243 Department of Physics, University of California, 1 Shields Avenue, Davis, CA 95616-5270, USA\n- 244 Department of Physics and Astronomy, University of Padova, Via 8 Febbraio, 2-35122 Padova, Italy\n- 245 INAF Osservatorio Astronomico di Padova, Vicolo della Osservatorio 5, I-35122 Padova, Italy\n- 246 Department of Physics, University of California, Santa Barbara, CA 93106-9530, USA\n- 247 Las Cumbres Observatory, 6740 Cortona Dr Ste 102, Goleta, CA 93117-5575, USA\n- 248 School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel\n- 249 Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK\n- 250 Department of Physics, University of Warwick, Coventry, CV4 7AL, UK\n- 251 DARK, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark\n- 252 Instituto de Astrof'ısica de Andaluc'ıa (IAA-CSIC), Glorieta de la Astronom'ıa s/n, 18008 Granada, Spain  \n- 253 Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF\n- 254 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, United Kingdom\n- 255 Max-Planck-Institut fur extraterrestrische Physik, 85740 Garching, Giessenbachstr. 1, Germany\n- 256 Birmingham Institute for Gravitational Wave Astronomy and School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT, UK\n- 257 INAF, Institute of Space Astrophysics and Cosmic Physics, Via Gobetti 101, I-40129 Bologna, Italy\n- 258 School of Physics and Astronomy, Monash University, VIC 3800, Australia; Monash Centre for Astrophysics, Monash University, VIC 3800, Australia\n- 259 The Oskar Klein Centre, Department of Astronomy, AlbaNova, Stockholm University, SE-106 91 Stockholm, Sweden\n- 260 Anton Pannekoek Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, the Netherlands\n- 261 ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, the Netherlands\n- 262 Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 76100, Rehovot, Israel\n- 263 M.V.Lomonosov Moscow State University, Physics Department, Leninskie gory, GSP-1, Moscow, 119991, Russia\n- 264 M.V.Lomonosov Moscow State University, Sternberg Astronomical Institute, Universitetsky pr., 13, Moscow, 119234, Russia\n- 265 Observatorio Astronomico Felix Aguilar (OAFA) , National University of San Juan, Argentina\n- 266 Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina\n- 267 South African Astrophysical Observatory, PO Box 9, 7935 Observatory, Cape Town, South Africa\n- 268 Irkutsk State University, Applied Physics Institute, 20, Gagarin blvd,664003, Irkutsk, Russia\n- 269 Blagoveschensk State Pedagogical University, Lenin str., 104, Amur Region, Blagoveschensk 675000\n- 270 Instituto de Astrof'ısica de Canarias Via Lactea, s/n E38205 - La Laguna (Tenerife), Spain\n- ∗ Deceased, February 2017.\n- † Deceased, December 2016."}