2013ApJ...773..144N

We present five new transit light curves of GJ 1214b taken in the BJHK _sbands. Two transits were observed in the B band using the Subaru Prime Focus Camera (Suprime-Cam) and the Faint Object Camera and Spectrograph (FOCAS) instruments on board the Subaru 8.2 m telescope, and one transit was done in the JHK_s bands simultaneously with the Simultaneous Infrared Imager for Unbiased Survey (SIRIUS) camera on the Infrared Survey Facility (IRSF) 1.4 m telescope. Markov Chain Monte Carlo analyses show that the planet-to-star radius ratios are R_p/R_s= 0.11651±0.00065 (B band, Subaru/Suprime-Cam), R_p/R_s= 0.11601±0.00117 (B band, Subaru/FOCAS), R_p/R_s= 0.11654 ±0.00080 (J band, IRSF/SIRIUS), iR_p/R_s = 0.11550_–0.00153^+0.00142 (H band, IRSF/SIRIUS), and R_p/R_s = 0.11547±0.00127 (K_sband, IRSF/SIRIUS). The Subaru Suprime-Cam transit photometry shows a possible spot-crossing feature. Comparisons of the new transit depths and those from previous studies with the theoretical models by Howe & Burrows suggest that the high molecular weight atmosphere (e.g., 1% H₂ O + 99% N₂) models are most likely, however, the low molecular weight (hydrogen-dominated) atmospheres with extensive clouds are still not excluded. We also report a long-term monitoring of the stellar brightness variability of GJ 1214 observed with the MITSuME 50 cm telescope in the g', R_c, and I_c bands simultaneously. The monitoring was conducted for 32 nights spanning 78 nights in 2012, and we find a periodic brightness variation with a period of P_s= 44.3±1.2 days and semi-amplitudes of 2.1%±0.4% in the g' band, 0.56%±0.08% in the R_cband, and 0.32%±0.04% in the I_cband.