These studies have included the detections of Rayleigh scattering by high altitude hazes also in WASP-12b [@Sing2013], additional unknown optical absorbers in HAT-P-1b (@Nikolov2014), a cloud deck masking the majority of the NaI absorption and near infrared water features in WASP-31b [@Sing2015] and a clear atmosphere consistent with solar and sub-solar metallicities in WASP-39b (@Sing2016; @Fischer2016).

Ground-based measurements of hot Jupiter transmission signals have also found success, beginning with the detection of the narrow component of NaI in HD189733b [@Redfield2008] and HD209458b (@Snellen2008; @Langland-Shula2009). More recent results have included further detections of sodium (e.g. @Wood2011; @Zhou2012), potassium (e.g. @Sing2011_XO2b; @Wilson2015), blueward scattering slopes (e.g. @Jordan2013; @Stevenson2014), and atmospheres dominated by clouds or hazes (e.g. @Gibson2013_wasp29; @Mallonn2016).

Although there has been success with ground-based spectroscopic observations they are more susceptible to systematics arising from, for example, differential slit losses (e.g. @Sing2012). A simpler approach, which avoids this problem, is to use photometers to perform simultaneous broadband multi-wavelength measurements. These studies have included evidence for large blueward slopes (e.g. @Southworth2012; @Southworth2015; @Mancini2016), enhanced absorption around the alkali metal lines (e.g. @Mancini2013; @Bento2014) and transmission spectra most consistent with clouds (e.g. @Mallonn2015_hat12). By observing the planetary radius at carefully selected wavelengths we can 