POSSIBLE SUPERNOVA IN UGC02756 NED01
Zhangwei Jin(Ningbo, Zhejiang, China) and Xing Gao (Urumqi, Xinjiang, China), report the discovery of a possible supernova (mag approximately 15.8) on a 40-s survey image (limiting mag about 19.5)taken by Xing Gao in Xingming ObservationSky Survey(C42) around Oct.22.79529 UT,2011. using a unfilted CCD ( + Celestron C14 Schmidt-Cassegrain telescope D=350-mm @f/6.9 ).the new object approximately located at R.A. =03h 29m 35s.30 Decl.=+40°52’02”.9(equinox 2000.0). Which is about 2.3″ east and 5.1″ south of the center of the UGC02756 NED01.
Nothing is visible at this position on archival images taken on Oct.08 (limiting mag 19.5) and Oct. 06 (limiting mag 19.0) or on the DSS(POSS2/UKSTU Red) from Sep. 29,1989(limiting mag about 19.8).
XM24ZJ C2011 10 22.79529 03 29 35.30 +40 52 02.9 15.8 V C42
All images can be seen from: http://www.xjltp.com/XOSS/XM24ZJ/XM24ZJ.htm
C42,Xingming Observatory, Mt. Nanshan. Observers Z.Jin, X.Gao ,Measurers Z.Jin 0.35-m f/6.9 Schmidt-Cassegrain telescope and CCD.
SUPERNOVA 2011gy IN UGC 2756 = J03293530+4052029
Zhangwei Jin (Ningbo, Zhejiang, China) and Xing Gao (Urumqi, Xinjiang,
China) report the discovery of a possible supernova (mag approximately 15.8)
on a 40-s unfiltered CCD survey image (limiting mag about 19.5) taken by Xing
Gao in the course of the Xingming Observation Sky Survey around Oct. 22.795 UT
using a 0.35-m f/6.9 Celestron C14 Schmidt-Cassegrain telescope. The new
object is approximately located at R.A. = 3h29m35s.30, Decl. = +40d52’02”.9
(equinox 2000.0), which is about 2″.3 east and 5″.1 south of the center of the
galaxy UGC 2756 = MCG +7-8-15 = PGC 12982. Nothing is visible at this position
on archival images taken at Mt. Nanshan on Oct. 6 (limiting mag 19.0) and 8
(limiting mag 19.5) or on a Digitized Sky Survey red plate from 1989 Sept. 29
(limiting mag about 19.8). Their images have been posted at the following
website URL: http://www.xjltp.com/XOSS/XM24ZJ/XM24ZJ.htm. The variable was
designated as PSN J03293530+4052029 when it was posted on the Central Bureau’s
TOCP webpage and is here designated SN 2011gy based on the spectroscopic
confirmation reported below.
Additional unfiltered CCD magnitudes for 2011gy: Oct. 23.211 UT, 15.5
(R. A. Koff, Bennett, CO, USA; Meade 0.25-m f/10 reflector + Apogee AP-47p CCD
camera; position end figures 35s.30, 03″.4; UCAC3 reference stars; limiting
magnitude 18.2); 23.287, 16.1 (Joseph Brimacombe, Cairns, Australia; position
end figures 35s.27, 03″.8); 23.500, 15.4 (C. Jacques and E. Pimentel, Belo
Horizonte, Brazil; remotely using the GRAS G11 telescope in New Mexico, USA;
position end figures 35s.34, 03″.0; UCAC2 reference stars; limiting magnitude
18.5; image posted at website URL http://ceamig-rea.net/tocp/P12982_tocp.jpg).
S. Taubenberger and M. Klauser, Max-Planck-Institut fuer Astrophysik;
S. Hachinger, S. Benetti, and S. Valenti, Istituto Nazionale di Astrofisica,
Osservatorio Astronomico di Padova; and M. Fiaschi, Dipartimento di Astronomia,
Universita di Padova, on behalf of a larger collaboration, report that a
spectrum of PSN J03293530+4052029 = SN 2011gy, obtained on Oct. 23.92 UT with
the Ekar-Copernico 1.82-m Telescope (+ AFOSC; range 350-810 nm, resolution 2.4
nm) shows it to be a normal type-Ia supernova a few days before maximum light.
Cross-correlation with a library of supernova spectra using GELATO (Harutyunyan
et al. 2008, A.Ap. 488, 383; publicly available at https://gelato.tng.iac.es)
yields a best match with spectra of SN 1998bu at half a week to one week before
maximum light. Adopting a recession velocity 5061 km/s for MCG +7-8-15 (Emilio
et al. 1999, PASP 111, 438; via NED), the expansion velocity measured from the
Si II 635.5-nm line is about 12000 km/s.
T. Zhang, National Astronomical Observatories of China (NAOC); J. Chen,
and X. Wang, Tsinghua Center for Astrophysics, Tsinghua University; and L. Lin
and X. Kong, University of Science and Technology of China, report on an
optical spectrogram (range 350-820 nm) of PSN J03293530+4052029 = SN 2011gy
that was obtained on Oct. 24.73 UT with the 2.16-m telescope (+ OMR) at the
Xinglong Station of the NAOC. The spectrum is consistent with a type-Ia
supernova at about one week before maximum light. After removal of the host-
galaxy recession velocity of about 5061 km/s (from NED), they find the
absorption minimum of the Si II 635.5-nm line to be blueshifted by about 12000
km/s. Cross-correlation with a library of supernova spectra using the
“Supernova Identification” code (SNID; Blondin and Tonry 2007, Ap.J. 666,
1024) shows that 2011gy matches with SN 2002er at -6 days.