A Revised Orbital Ephemeris for HAT-P-9b

摘要

We present here three transit observations of HAT-P-9b taken on 14 February2010, 18 February 2010, and 05 April 2010 UT from the University of Arizona's1.55 meter Kuiper telescope on Mt. Bigelow. Our transit light curves wereobtained in the I filter for all our observations, and underwent the samereduction process. All three of our transits deviated significantly(approximately 24 minutes earlier) from the ephemeris of Shporer et al. (2008).However, due to the large time span between our observed transits and those ofShporer et al. (2008), a 6.5 second (2 sigma) shift downwards in orbital periodfrom the value of Shporer et al. (2008) is sufficient to explain all availabletransit data. We find a new period of 3.922814 +/- 0.000002 days for HAT-P-9bwith no evidence for significant nonlinearities in the transit period.