  OCTOCAM is a multi-channel imager and spectrograph that has been proposed for
the 10.4m GTC telescope. It will use dichroics to split the incoming light to
produce simultaneous observations in 8 different bands, ranging from the
ultraviolet to the near-infrared. The imaging mode will have a field of view of
2' x 2' in u, g, r, i, z, J, H and Ks bands, whereas the long-slit
spectroscopic mode will cover the complete range from 4,000 to 23,000 {\AA}
with a resolution of 700 - 1,700 (depending on the arm and slit width). An
additional mode, using an image slicer, will deliver a spectral resolution of
over 3,000. 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 will be occupying a region of the time resolution - spectral resolution
- spectral coverage diagram that is not covered by a single instrument in any
other observatory, with an exceptional sensitivity.
