K_s-band secondary eclipses of WASP-19b andWASP-43b with the Anglo-Australian Telescope

We report new K_s-band secondary eclipse observations for the hot-Jupiters WASP-19b and WASP-43b. Using the IRIS2 infrared camera on the Anglo-Australian Telescope (AAT), we measured significant secondary eclipses for both planets, with depths of 0.287_-0.020^+0.020 per cent and 0.181_-0.027^+0.027 per cent for WASP-19b and WASP-43b, respectively. We compare the observations to atmosphere models from the VSTAR line-by-line radiative transfer code, and examine the effect of C/O abundance, top layer haze, and metallicities on the observed spectra. We performed a series of signal injection and recovery exercises on the observed light curves to explore the detection thresholds of the AAT+IRIS2 facility. We find that the optimal photometric precision is achieved for targets brighter than K_mag = 9, for which eclipses as shallow as 0.05 per cent are detectable at >5σ significance.