A ground-based search for L band thermal emission from TrES-1

Recent observations using the Spitzer Space Telescope have detected the thermal emission from several transiting planets, including TrES-1. Charbonneau et al. (2005) found that the 4.5 mu m eclipse depth for TrES-1 was smaller than expected; theoretical models predict that hot Jupiters like TrES-1 should have a strong peak in their emission at 4 mu m. We followed up this initial Spitzer measurement with spectral observations of the secondary eclipse of TrES-1 in L band using NIRI on Gemini North, which allowed us to create a bandpass centered on the predicted 4 gm peak. The simultaneous observation of a second star allows us to calibrate out time-dependent variations in the common-mode terrestrial atmospheric absorption and seeing effects. We obtained a, series of 758 spectra spanning g two secondary eclipses of TrES-1 and present the preliminary results of our analysis in this poster.