Photometric Observation and Study of the Transiting Exoplanetary System HAT-P-8

Three transit events of HAT-P-8 are observed by using the 1 m telescope of Yunnan Observatory and 2.4 m telescope of Lijiang Observing Station in 2009 and 2012, respectively. The observational data were reduced with the coarse de-correlation and SysRem algorithms in order to obtain high signal to noise ratio for the transit feature. The MCMC (Markov Chain Monte Carlo) technique is applied to analyze three transit light curves simultaneously, then the new parameters of HAT-P-8 system are derived. The new value of the radius for HAT-P-8b is smaller than the one given by Latham et al., but it is consistent with the value derived by Mancini et al. recently. By linear fitting to the 23 mid-transit times with high precision, the orbital period of HAT-P-8b is refined as P=3.0763461±0.0000021 d. No obvious TTV (Transit Timing Variation) signal can be found from the present (O-C) analysis