Abstract
In June 2011 we attempted to measure the first atmospheric transmission spectrum of an exoplanet with the GTC. We observed the hot Jupiter TrEs-2b during two transit epochs using the long-slit spectroscopic mode of OSIRIS. The technique consists of doing differential spectrophotometry by placing the planet host and a nearby star on a wide slit during a planetary transit. We then monitor both objects for the duration of the event to obtain simultaneous transit coverage at wavelengths between ~5000 and 9000 Å. We present here the results of our first attempt with this new technique, which holds the potential of providing a 5-10 fold improvement on the efficiency of exoplanet primary and secondary eclipse observations with the GTC. Finally, we also present a summary of the science done so far with observations from the ESO/GTC program 182.C.2018.
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