A Revised Orbital Ephemeris for HAT-P-9b

TL;DR

This paper refines the orbital period of exoplanet HAT-P-9b using new transit observations, showing a slight adjustment to the previously known period and confirming its linearity.

Contribution

The study provides a revised orbital ephemeris for HAT-P-9b based on new transit data, improving the accuracy of its orbital parameters.

Findings

Revised orbital period: 3.922814 +/- 0.000002 days

Transit observations deviated from previous ephemeris by ~24 minutes

No evidence of nonlinearities in the transit period

Abstract

We present here three transit observations of HAT-P-9b taken on 14 February 2010, 18 February 2010, and 05 April 2010 UT from the University of Arizona's 1.55 meter Kuiper telescope on Mt. Bigelow. Our transit light curves were obtained in the I filter for all our observations, and underwent the same reduction 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 of Shporer et al. (2008), a 6.5 second (2 sigma) shift downwards in orbital period from the value of Shporer et al. (2008) is sufficient to explain all available transit data. We find a new period of 3.922814 +/- 0.000002 days for HAT-P-9b with no evidence for significant nonlinearities in the transit period.