Binary Star Observations With the Hubble Space Telescope Fine Guidance Sensors. II. Bright Hyades

Abstract

The paper reports on astrometric measurements performed with the Hubble Space Telescope fine guidance sensors in the transfer scan mode on selected bright member stars of the Hyades cluster. The purpose of these measurements was to quickly validate this mode of operation of the fine guidance sensors - in the presence of many optical anomalies - and to assess the frequency of binaries in the 5-250 milliarcseconds (mas) range in the 6-12 apparent magnitude interval. Of the 16 stars which have been examined, one shows definite evidence of duplicity. The paper discusses the data acquisition, smoothing and, especially, rectification. The latter is a nontrivial issue given the existing optical aberrations and the lack of calibration in the ordinary sense of the term.