The transit game is getting to be a competitive global business. No sooner is a new transit announced than amateur astronomers worldwide are on the sky to obtain follow-up observations. Tonny Vanmunster, of Landen Belgium and Ron Bissinger of Pleasanton California are generally among the first to check in with confirmations. Vanmunster nailed TrES-1 a mere week after its announcement in 2004. Last summer, Bissinger caught HD 149026b on literally the day it was announced. In the case of TrES-2, which was announced yesterday, it looks like Vanmunster has snagged the prize. “What’s up, Cali?”
[Actually, it was both cloudy and the middle of the day in Pleasanton while Vanmunster was on the sky. But there's a transit tomorrow night, Sept. 10/11 PDT, that Ron'll likely catch.]
Here’s Vanmunster’s light curve. The transit was in progress at dusk in Belgium, so he was able to observe only the latter part of the event.
Here are some technical details : observations were made at CBA Belgium Observatory, using two 0.35-m f/6.3 Celestron telescopes, each equipped with an SBIG ST-7XME CCD camera. I simultaneously made unfiltered and R-band observations (hence the 2 telescopes). The included light curve is unfiltered, and each dot in the curve is the average value of 5 successive observations (binned). The gray lines show the standard deviation (about 4 millimag on average). Exposure time was 15 to 20 sec.
The egress is very evident in the light curve, and happened right at the predicted time. The transit depth was approx. 0.0155 mag, which again corresponds well with the value published in the discovery paper.
Follow-up observations such as the ones made by Vanmunster and Bissinger can be very scientifically useful. For example, Vanmunster’s 2004 observations allowed us to get an improved estimate of the TrES-1 planetary radius, and he co-authored a journal article with us on that topic. Both Vanmunster and Bissinger were involved in the discovery of X0-1, and both are co-authors on the recent Shankland et al. paper which I’ll talk up in an upcoming post.