Eclipses of HS 1804+6753 = EX Dra

HS 1804+6753 is a recently discovered deeply eclipsing dwarf nova (cf. HT Cas,DV UMa, S10932,DO Leo).

The object was first detected by the Einstein survey (= MS 1804+6753), and was independently discovered as a UV-excess object by the Kiso survey (Noguchi et al. 1982, PASJ 34, 407). However, the importance of this object was not noticed until Barwig et al. (1994, in Abstracts of IAU Symp. 165, Compact Stars in Binary Systems p.89) revealed its nature as a member of eclipsing dwarf novae, from which a wealth of our basic understandings in cataclysmic variables and accretion disks has been derived.

A detailed study of the accretion disk and the secondary star is presented by Billington et al. 1996 (MNRAS 278, 673).

Eclipse observations of HS 1804+6753

sequential CCD images of newly-discovered eclipsing

dwarf nova HS 1804+6753, taken by Makoto Iida (VSOLJ)

  instruments:   16-cm refl. + ST-6 unfiltered
  date:          1995 Sep. 21 11h54m05s UT - 12h20m53s UT
                 (time elapsed from the upper left panel to the right)
  exposure time: 150 sec

  Note a clear eclipse caught by this small telescope!