MuSCAT: a multicolor simultaneous camera for studying atmospheres of transiting exoplanets
Narita et al
We report a development of a multi-color simultaneous camera for the 188cm telescope at Okayama Astrophysical Observatory in Japan. The instrument, named MuSCAT, has a capability of 3-color simultaneous imaging in optical wavelength where CCDs are sensitive. MuSCAT is equipped with three 1024x1024 pixel CCDs, which can be controlled independently. The three CCDs detect lights in g′2 (400--550 nm), r′2 (550--700 nm), and zs,2 (820--920 nm) bands using Astrodon Photometrics Generation 2 Sloan filters. The field of view of MuSCAT is 6.1x6.1 arcmin2 with the pixel scale of 0.358 arcsec per pixel. The principal purpose of MuSCAT is to perform high precision multi-color transit photometry. For the purpose, MuSCAT has a capability of self autoguiding which enables to fix positions of stellar images within ~1 pix. We demonstrate relative photometric precisions of 0.101%, 0.074%, and 0.076% in g′2, r′2, and zs,2 bands, respectively, for GJ436 (magnitudes in g′=11.81, r′=10.08, and z′=8.66) with 30 s exposures. The achieved precisions meet our objective, and the instrument is ready for operation.