OCTOCAM: A multi-channel imager and spectrograph to explore the transient Universe

OCTOCAM is a multi-channel imager and spectrograph that has been proposed for the 10.4m Gran Telescopio Canarias (GTC) telescope as a next generati on instrument. OCTOCAM will be based on dichroics to split the incoming light to produce sim ultaneous observations in 8 different bands, ranging from the ultraviolet to the near-infrared. T he imaging mode will have a field of view of 2×2 in u, g, r, i, z, J, H andKs bands, whereas the long-slit spectroscopic mode will cover the complete range from 4000 to 23000 Å with a resolutio n of 700 1700 (depending on the arm and slit width). An additional mode, using an image slice r, will provide a spectral resolution of over 3000. As a further feature, it will use state of the art detectors to reach high readout speeds of the order of tens of milliseconds. In this way, OCTOCAM wil l be occupying a region of the time resolution spectral resolution spectral coverage d iagram that is not covered by a single instrument in any other observatory, with an exceptional se nsitivity.