OMC: An Optical Monitoring Camera for INTEGRAL

The INTEGRAL payload has been designed to study simultaneously gamma-ray sources in a wide field of view over many decades in energy (around 2 eV + 4 keV − 20 MeV) and thus make a major contribution to short time-scale high-energy astrophysics. The OMC will observe the optical emission from the prime targets of the gamma-ray instruments with the support of the x-ray monitor. This capability will provide invaluable diagnostic information on the nature and the physics of the sources over a broad wavelength range. The main scientific objectives will be: (1) to monitor the optical emission from the sources observed by the gamma- and x-ray instruments, measuring the time and intensity structure of the optical emission for comparison with variability at high energies, and (2) to provide the brightness and position of the optical counterpart of any gamma- or x-ray transient taking place within its field of view. The OMC will be based on a refractive optics with an aperture of 50 mm focused onto a large format CCD (1024 × 2048 pixels) working in frame transfer mode (1024 × 1024 pixels imaging area). With a field of view of 5° × 5° it will be able to monitor sources down to V = 19 mag. Typical exposures will consist of 10 integrations of 100 seconds each.