BVRc photometry of optical and soft X-ray transient CSS 081007:030559+054715
(HV Cet)
V.P.Goranskij and N.V.Metlova (SAI, Moscow Univ.)
To be published in Astronomer's Telegram.
We report the results of photometric BVRc monitoring of soft X-ray transient
and possible O/Ne class nova CSS 081007:030559+054715 (ATEL #1825,
ATEL #1835, ATEL #1847, ATEL #1873, ATEL #1910). Using 60-cm
telescope of SAI Crimean Station (Ukraine) and CCD Apogee-47,
we have taken 211 V band observations in 13 nights in the time range
between 2008 Dec 3 and 2009 Feb 19. We have also a few observations
in the B and Rc bands. The comparison star was GSC 0061.1376
(3:05:53.5 +5:46:26, 2000; v=15.1), the following magnitudes were determined
by us for it: B,V,Rc = (15.69,15.00,14.48). We measured also 5 check stars
in the vicinity of the nova. The accuracy of observations is 0.02 mag
(excluding one night 2008 Dec 11 when the accuracy was 0.06 mag due
to close moon location). The brightness of the nova varied between 16.01
and 17.07 in V band, its colours were B-V=-0.08+/-0.04 and V-Rc=+0.20+/-0.07.
The light curve of nova displays 50-day long plateau at the level of 16.3 V
finished on 2009 Jan 22 and subsequent rapid decay. The amplitude of
variations during plateau was 0.40 mag.
Our observations do not confirm Swift 1.77 day period reported in
ATEL #1873 based on X-ray and UV observations. Although, a nearby
value of period, 1.694+/-0.005 day presents the light curve very similar to
X-ray one described there. Analysing 203 observations in the plateau
stage with the Lafler-Kinman PDM method, we found
also a possible period 0.6106+/-0.0006 day with the asymmetric light curve
resembling the light curves of novae CI Aql and V723 Cas passed
through SSS phase. The mean amplitudes of light curves with these
two periods are of about 0.25 mag. Both periodic solutions include
some essential contradicted observations and should be verified
with additional photometric data if available. So, we made our original
tables of observations
accessible in
Internet .
Figures. Light curves of CSS 081007:030559+054715 folded with period
1.694 day (left) and 0.6106 day (right). Light elements are given at the
bottom of each figure.
