GCN №7166 X-ray transient in NGC 2770: Optical observationsTITLE: GCN CIRCULAR
NUMBER: 7166
SUBJECT: X-ray transient in NGC 2770: Optical observations with
DATE: 08/01/11 15:44:16 GMT
FROM: Denis Denissenko at IKI, Moscow <
denis@hea.iki.rssi.ru>
D. Denisenko (IKI, Moscow), S. Korotkiy (Ka-Dar obs.), T. Kryachko
(Astrotel obs., KSU), B. Satovskiy (Astrotel obs., KSU),
K. Sokolovsky (ASC LPI, SAI MSU) report:
We took three 300-sec unfiltered images of NGC 2770 between 19:00 and 19:18
UT
on 2008 Jan 10 with 300-mm f/7.7 robotic telescope equipped with STL-11000M
CCD camera. The telescope is located at Kazan State University Astrotel
observatory (Karachay-Cherkessia, Russia). The optical source reported by
Deng & Zhu (GCN 7160) and Thoene et al. (GCN 7161) is clearly detected on
individual images with SNR=18. Using the same comparison star as in D'Elia
et al. (GCN 7162), we have measured unfiltered magnitude (with R zero-point)
of the transient 18.1+/-0.1
(JD 2454476.2979).
The finding chart is available at
ftp://scan.sai.msu.ru/pub/XRT_NGC2770/OT-NGC2770-Astrotel.jpgThe individual fits images can be downloaded from
ftp://scan.sai.msu.ru/pub/XRT_NGC2770/ This message can be cited.
CBET №1202
SUPERNOVA 2008D IN NGC 2770
Further to CBET 1187, W. Li and A. V. Filippenko report the discovery
of an apparent supernova (mag 17.5) on an unfiltered KAIT image taken on
Jan. 11.42 UT. The new object (designated 2008D) is located at R.A. =
9h9m30s.65, Decl. = +33o8'20".3 (equinox 2000.0), which is 38".3 west and
55".6 north of the nucleus of NGC 2770, and located on a spiral arm of the
galaxy. A KAIT image on Jan. 2.43 showed nothing at this location (limiting
mag 19.6). SN 2007uy (cf. IAUC 8908; CBET 1191) was also in NGC 2770 and
was measured at mag 15.5 on Jan. 11.42.
Li and Filippenko note that 2008D is coincident in position with a
transient in NGC 2770 that was first reported in x-ray observations by
Swift/XRT (Berger and Soderberg,
http://gcn.gsfc.nasa.gov/gcn3/7159.gcn3= GCN 7159; Kong and Maccarone,
http://www.astronomerstelegram.org/?read=1355),
and then was reported optically by Deng and Zhu (GCN 7160), Thoene et al.
(GCN 7161),
and Denisenko et al. (GCN 7166). In particular, Denisenko et al.
reported an unfiltered magnitude of 18.1 for the new object on Jan. 10.8.Compared to the brightness of the new object in the KAIT image on Jan. 11
(mag 17.5), the new object seems to have brightened significantly.
Li and Filippenko add that photometry and spectroscopy of this very
interesting object are encouraged. A redshift measurement is important to
establish whether 2008D is in NGC 2770. Spectra obtained by Soderberg et al.
(GCN 7165) reveal a smooth, featureless continuum with a suggestion of a
broad bump near 550.0 nm that may indicate the emergence of supernova
features.
