Discovery of deep eclipses in the cataclysmic variable 1RXS J020929.0+283243
ATel #652; D. V. Denisenko (IKI, Moscow), R. A. Sunyaev (IKI, Moscow; MPA, Garching), Z. Aslan (TUG, Antalya), I. Khamitov (TUG, Antalya)
on 8 Nov 2005; 10:17 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: S.A.Grebenev (sergei@hea.iki.rssi.ru)
Subjects: Optical, X-ray, Cataclysmic Variable, Variables
Referred to by ATel #: 666
In course of the search for optical identifications of bright ROSAT sources with the 1.5-m Russian-Turkish Telescope RTT150 (Bakyrlytepe, Turkey) we have discovered very deep (4.5 mag) eclipses of the cataclysmic variable in the error box of 1RXS J020929.0+283243. Six eclipses with duration of about 6 min were observed during the nights of Oct. 22-27, 2005. The orbital period is 0.06685(2) d, or 96.26 min. Light elements are: T = 2453666.543 + 0.06685 * E. Fine details are present in the light curve which are most probably caused by the changing geometry of an accretion disc. The total range of variations is 17.0-21.5 mag. We note the marginal detection of a possible "central flash" event in the middle of eclipses at JD 2453669.484 and 2453669.551. This flash can be explained by the larger companion acting as a lens bending the light of a white dwarf in the center of an eclipse. Light curve covering two periods between 21:50 UT on Oct. 25 and 01:30 UT on Oct. 26 is available at http://hea.iki.rssi.ru/~denis/J020929-RTT_LC-051025.gif Coordinates of the cataclysmic variable measured relative to UCAC2 catalogue are: RA=02h09m29.82s, Dec=+28o32'29.1" (J2000.0).
We also note the presence of another object of stellar appearance within the ROSAT error circle 10.1"E and 18.8"N from the CV (position end figures 30.59s, 47.9") with a magnitude of 18.5 surrounded by 4 faint galaxies. The object is showing variability with an amplitude of 0.3 mag on the timescale of days. The color combined chart of the 3'x2.5' region can be found at http://hea.iki.rssi.ru/~denis/J020929-RTT_field-color.jpg
Future optical observations are necessary to determine the type of variability of this CV (UGSU, UGWZ or AM) and to monitor the nearby source. We also encourage the observations by X-ray telescopes with angular resolution better than 10" to resolve the structure of the source and to look for the X-ray eclipses of the CV using the ephemeris provided above.
