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Astron. Astrophys. 327, 173-182 (1997)

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1. Introduction

HS 1804 + 6753 is a new so called double eclipsing cataclysmic binary, which exhibits eclipses of the white dwarf and of the hot spot. It has been detected in the course of the Hamburger Quasar Survey (Bade et al. 1989). The coordinates of this object are [FORMULA] and [FORMULA]. A finding chart copied from the Digital Sky Survey is displayed in Fig. 1. HS 1804 + 6753 is a relatively bright CV ([FORMULA]) in which the eclipse ingress of the white dwarf and of the hot spot are distinguishable. Therefore, the relevant physical parameters of the system can be derived with relatively high precision. Of 800 known cataclysmic binaries, only five exhibit double eclipses. This makes this new CV a fascinating object for extended observations, even more so because it seems to be frequently in outburst. We have monitored HS 1804 + 6753 since April 1991 with telescopes at Wendelstein and Calar Alto collecting spectra as well as high-speed photometric data. Our first results were presented at the IAU symposium 165 (Barwig et al. 1993). Further spectroscopic observations have been reported by Billington et al. (1996).

In Sect. 2, the journal of observations is presented. Data analysing techniques are discussed in Sect. 3 giving masses and radii. In Sect. 4, additional physical parameters are determined by Monte-Carlo techniques.

[FIGURE] Fig. 1. Finding chart for HS 1804 + 6753, taken from the Digital Sky Survey. The coordinates of the system are [FORMULA] and [FORMULA]. North is up and east is left; scale: 10'x10'.
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© European Southern Observatory (ESO) 1997

Online publication: April 8, 1998
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