& 1.5 $\pm$ 0.4\
Src. 12 & 12 05 40.92 $\pm$ 0.05 & 50 32 58.6 $\pm$ 0.3 & 13.9 $\pm$ 4.4 & 1.4 $\pm$ 0.4\
Src. 13 & 12 05 35.80 $\pm$ 0.03 & 50 32 31.4 $\pm$ 0.3 & 11.6 $\pm$ 4.1 & 1.2 $\pm$ 0.4\
Src. 14 & 12 05 34.02 $\pm$ 0.01 & 50 32 12.9 $\pm$ 0.2 & 8.2 $\pm$ 3.5 & 0.8 $\pm$ 0.3\
Src. 15 & 12 05 30.13 $\pm$ 0.04 & 50 31 21.0 $\pm$ 0.2 & 8.0 $\pm$ 3.2 & 0.8 $\pm$ 0.3\
SN2009dd & 12 05 34.10 & 50 32 19.4 & 8.0 $\pm$ 3.2 & 0.8 $\pm$ 0.3\

X-ray properties of the ULX {#xrayprop}
---------------------------

For the ULX N4088–X1, we obtain an X-ray luminosity of $L_\mathrm{0.3-10 keV} = 2.2 \times 10^{39}$ erg s$^{-1}$ using the observed *Chandra* fluxes derived from the count rates assuming the power-law model described in Sect. \[chandraobservations\]. The *Chandra* detection of N4088–X1 shows that the source is located at RA(J2000) = 12$^h$05$^m$32$^s$.33 $\pm$ 0$^s$.01, Dec.(J2000) = 50$^{\circ}$3245.9 $\pm$ 0.1. The positional 1$\sigma$-errors correspond to the statistical uncertainties affecting the *wavdetect* centroid algorithm and the dispersion of photons due to the PSF. In addition, the *Chandra* 