AAS 197, January 2001
Session 116. Virtual Observatory: Data, Services, Tools and Software
Display, Thursday, January 11, 2001, 9:30-4:00pm, Exhibit Hall

## [116.13] GB6 Radio Source Variability at 4.85 GHz

P. C. Gregory, P. Capak, D. Gasson (UBC), W. K. Scott (Univ. of Calgary)

The NRAO seven-beam receiver was used on the former Green Bank 91m telescope, during 1986 November and 1987 October, to repeatedly survey the declination band (0o < \delta < 70o) at 4.85 GHz. This data base has been used to extract variability information for sources in the GB6 catalog (Gregory et al. ApJS, 103, 1996), a large unbiased sample of sources derived from the combined survey images.

This variability information consists of two parts. First, there is an indicator of the long term variability, based on two flux density measurements, one derived from the 1986 image set and the other from the 1987 image set. Second, there is an indicator of the short term variability, based on an analysis of the daily scan data that was used to construct the images.

Long term variability information is available for 97% of the 75,162 GB6 sources. It has been possible to derive short term variability information for 20,963 GB6 sources. The exact number of daily measurements depends on source declination, ranging from a mean of 7 (both epochs) for a source at declination 0o to a mean of 20 for a declination of 70o.

This large variability data base is being released to the astronomical community through:http://pulsar.physics.ubc.ca/gregory/index.html''.