OMC: An Optical Monitoring Camera for INTEGRAL

The Optical Monitoring Camera (OMC) will observe the optical emission from the prime targets of the gamma-ray instruments onboard the ESA mission INTEGRAL, with the support of the JEM-X monitor in the X-ray domain. This capability will provide invaluable diagnostic information on the nature and the physics of the sources over a broad wavelength range. Its main scientific objectives are: (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 is based on a refractive optics with an aperture of 50 mm focused onto a large format CCD ($1024 \times 2048$ pixels) working in frame transfer mode ($1024 \times 1024$ pixels imaging area). With a field of view of $5^\circ\times5^\circ$ it will be able to monitor sources down to magnitude $V = 18$. Typical observations will perform a sequence of different integration times, allowing for photometric uncertainties below 0.1 mag for objects with $V\le16$.