XMM-Newton Optical Monitor Serendipitous UV Source Survey

Data Selection

The catalogue is populated with 753,578 sources from 2,417 observations between Feb 24, 2000 and Mar 29, 2007. This is not a complete sample because a fraction of observations were removed during data screening. We list the screening criteria below.

Time

Observations are included from between the dates 2000-02-28 and 2007-03-29.

Filter

Observing sequences during a pointing must include at least one exposure taken through the UVW2, UVM2 or UVW1 filters.

Instrument Mode

Only observations taken in imaging mode are included in the catalogue. Fast mode data, which localizes individual photons within a central 22x23 pixel window, are excluded because of the small window size. Similarly, 2x2 arcmin2 high-resolution central windows of the Rudi-5 default configuration are ignored, though note that in the majority of Rudi-5 observations, the central region is also recorded as an 8x8 arcmin2 low-resolution image which is included within the catalogue sample. Optical and UV grism observations, recording dispersed 0th and 1st order light, are excluded.

Astrometric Correction

The accuracy of XMM-Newton pointing is good to 1.81 arcsec (RMS). Boresight positions of each field are corrected by comparison of XMM-OM sources with the USNO-B1.0 catalogue, although a minimum number of source detections are required to perform the correction accurately. Only sources from images meeting the following criteria are included within the catalogue:

  1. There are > 4 source detections.
  2. The RMS residual between matched source positions and their USNO-B counterparts < 1.5 arcsec.
  3. The 1σ error in the computed boresight correction < 1.0 arcsec in both the Right Ascension and Declination directions.

Crowded Fields

Both the source detection algorithm and aperture photometry become increasingly uncertain in crowded fields due to source confusion and lack of background measures. Images are included within the catlogue where detected source density < 35 arcmin-2, corresponding to 10,000 sources within a full-frame image.

Manual Screening

Each image is screened visually for obvious problems. While there are no strict criteria for inclusion, only sources from those images that met the following were ingested:

  1. Images are not dominated by large scattered light features.
  2. Images show no evidence of telemetry corruption.
  3. Images show no obvious sign of spurious attitude drift.

In all three cases above, the likelihood of spurious sources is increased in the rejected images.