[vsnet-grb-info 5577] X-ray transient in NGC 2770: RTT150 optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7239
SUBJECT: X-ray transient in NGC 2770: RTT150 optical observations
DATE:    08/01/30 16:25:52 GMT
FROM:    Irek Khamitov at TUG  <irekk at tug.tug.tubitak.gov.tr>

I. Khamitov (TUG), I. Bikmaev, R. Gumerov,
A. Nemtinov, N. Sakhibullin (KSU/AST),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)

report:

We continued observations of the optical counterpart to X-ray transient in
NGC 2770, SN2008D (GCN Rep. 110.1, GCN Circ. 7160, 7161) with
Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National
Observatory, Turkey) in 26 (02:50-04:50UT), 27 (01:00-04:00UT), 28 
(04:05UT) Jan 2008 using ANDOR TE CCD (DW-436).

Series of BVRI direct images were taken on Jan 26 and 27, and also we made
300s R-exposure on Jan 28 under windy weather conditions (the seeing was
more then 2 arcsec for all observations).

The object shows no variability between the nignts at the level >~ 0.05mag.
In comparision with the our previous observations (11, 12 Jan, Bikmaev et
al., GCN7206) the OT is brighter approximatelly by 1.0 mag and 0.6 mag
in R and B bands respectively.

Assuming R=17.3 and B=17.7 magnitudes for USNO-A2.0 1200-06240802 star, we
estimate the following magnitudes for the transient:

Time, UT    t-t0,days   mag

Jan 26.14   16.58      R = 17.03
Jan 26.15   16.59      B = 18.06
Jan 27.09   17.53      B = 18.13
Jan 27.12   17.56      R = 17.01
Jan 28.17   18.61      R = 16.98

Also we found that in our previous circular there was a misprint in t-t0
column. The correct t-t0 values can be obtained by adding one day to the
values in that circular.


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