Near-Infrared Transit Photometry of Extra-Solar Planet HAT-P-54b

The results of near-infrared photometric observations of a transit event of an extrasolar planet HAT-P-54b are presented herein. Precise near-infrared photometry was carried out using the Nayuta 2 m telescope at Nishi-Harima Astronomical Observatory, Japan and Nishi-harima Infrared Camera (NIC). 170 J-, H-, and Ks-band images were taken in each band in 196 minutes. The flux of the planetary system was observed to decrease during the transit event. While the the Ks-band transit depth is similar to that in the r-band, the J- and H-band transits are deeper than those in the Ks-band. We constructed simple models of the planetary atmosphere and found that the observed transit depths are well reproduced by inflated atmosphere containing H2S molecule.