The Newton X-ray Multi-Mirror Mission (XMM) was launched in December, 1999 with a projected lifetime of 10 years. Although intended primarily as an X-ray observatory, XMM included a small but powerful optical/UV 30 cm telescope co-aligned with the X-ray telescopes for contemporaneous observations. The modified Ritchey-Chretien telescope is capable of detecting 24th magnitude sources in its 17 arcmin field of view. It provides images in the 160-600nm wave band with 1 arcsec resolution. MAST is serving a OM Mosaic product that uses a pipeline described by Kuntz et. al. OMCat: Catalog of Serendipitous Sources Detected with the XMM-Newton Optical Monitor PASP, 120:740-758
