Abstract:
We present seven light curves of the exoplanet systemHAT-P-3, taken as part of a transit timing
programme using the rapid imager to search for exoplanets instrument on the Liverpool Telescope.
The light curves are analysed using aMarkov chainMonte Carlo algorithm to update the
parameters of the system. The inclination is found to be i = 86.75⁺°·²²₋₀.₂₁◦, the planet-star radius
ratio to be Rp/R✴ = 0.1098⁺°·°°¹°₋₀.₀₀₁₂ and the stellar radius to be R✴ = 0.834⁺°·°¹⁸₋₀.₀₂₆ R , consistent
with previous results but with a significant improvement in the precision. Central transit times
and uncertainties for each light curve are also determined, and a residual permutation algorithm
is used as an independent check on the errors. The transit times are found to be consistent with
a linear ephemeris, and a new ephemeris is calculated as T c(0) = 245 4856.701 18 ± 0.000 18
HJD and P = 2.899 738 ± 0.000 007 d. Model timing residuals are fitted to the measured
timing residuals to place upper mass limits for a hypothetical perturbing planet as a function
of the period ratio. These show that we have probed for planets with masses as low as 0.33
and 1.81M⊕ in the interior and exterior 2:1 resonances, respectively, assuming the planets are
initially in circular orbits.
