HEAD 2000, November 2000
Session 24. X-Ray Binaries - Timing and Transients
Display, Wednesday, November 8, 2000, 8:00am-6:00pm, Bora Bora Ballroom

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[24.07] Position and Variability of {2A~1704+241}

W.A. Morgan, Jr. (Dickinson College), M.R. Garcia (CfA)

We present results of analyses of observations of the X-ray source 2A 1704+241 with the ROSAT Position Sensitive Proportional Counter (PSPC) and the High Resolution Imager (HRI). 2A 1704+241 was first associated with the M-giant star HD 154791 based upon observations with the HEAO 1 SMC and the {Einstein} IPC and analysis of a spectrum of HD 154791 obtained with the International Ultraviolet Explorer. This identification was unusual because there are few bright X-ray binaries associated with an M-giant star. We observed {2A~1704+241} with the PSPC and the HRI in order to determine more accurately the position of the X-ray source and in order to study the previously-seen 900-second variability in the Einstein data.

Based upon the previous identification and determination of the position of MS 1703.7+2417, an AGN in the field, and the position of three previously-unreported X-ray sources that we have associated with stars in the USNO-A2.0 catalog, we have confirmed the identification of the optical counterpart of the X-ray source {2A~1704+241} as HD 154791. In addition, we determine that there is little evidence for the 900-sec modulation seen by the Einstein IPC in the more recent PSPC data, and that there is no phase coherence in what modulation {\em is} noticeable.

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