Ground-based multisite observations of two transits of HD 80606b

TL;DR

This paper reports ground-based optical observations of two transits of HD 80606b, providing precise midtransit times and demonstrating coordinated multi-site observations to improve transit timing accuracy.

Contribution

It presents new ground-based transit observations of HD 80606b from multiple sites, refining transit timings and demonstrating the effectiveness of coordinated multi-site campaigns.

Findings

Midtransit time for September 2009: 2455099.196 ± 0.026 HJD.

Midtransit time for January 2010: 2455210.6502 ± 0.0064 HJD.

Transit timings are consistent with previous predictions and space-based observations.

Abstract

We present ground-based optical observations of the September 2009 and January 2010 transits of HD 80606b. Based on 3 partial light curves of the September 2009 event, we derive a midtransit time of T_c [HJD] = 2455099.196 +- 0.026, which is about 1 sigma away from the previously predicted time. We observed the January 2010 event from 9 different locations, with most phases of the transit being observed by at least 3 different teams. We determine a midtransit time of T_c [HJD] = 2455210.6502 +- 0.0064, which is within 1.3 sigma of the time derived from a Spitzer observation of the same event.