New double stars from HST

The data comprise a survey of observed guide stars, all of which are taken from the HST Guide Star Catalog, ranging in magnitude from 9 to 14. The survey results cover a parameter space for the newly found doubles, for the fainter stars, which are of smaller limiting angular separations than in any previous surveys.

The normal HST engineering telemetry data from 13,979 acquisitions on 4882 stars have been processed. The FGS guidance data can reveal duplicity with separations ranging from approximately 30mas, for the brighter stars, with small magnitude differences, up to the neighborhood of 500mas, and in some cases to 1000mas. The fraction of guide stars indicating duplicity is a function of the statistical criteria used but is over 5% at a very high level of confidence.