Hst Fine Guidance Sensor Astrometric Parallaxes for Three Dwarf Novae: Ss Aurigae, Ss Cygni, and U Geminorum

We report astrometric parallaxes for three well known dwarf novae obtained using the Fine Guidance Sensors on the Hubble Space Telescope. We found a parallax for SS Aurigae of π = 5.00 ± 0.64 mas, for SS Cygni we found π = 6.02 ± 0.46 mas, and for U Geminorum we obtained π = 10.37 ± 0.50 mas. These represent the first true trigonometric parallaxes of any dwarf novae. We briefly compare these results with previous distance estimates. This program demonstrates that with a very modest amount of HST observing time, the Fine Guidance Sensors can deliver parallaxes of unrivaled precision. Subject headings: Astrometry — novae, cataclysmic variables — stars: individual (SS Aurigae, U Geminorum, SS Cygni) Based partially on observations obtained with the Apache Point Observatory 3.5-meter telescope, which is owned and operated by the Astrophysical Research Consortium.