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THE ASTRONOMER Electronic Circular No 2709      2011 Feb 01 18.03UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK      Backup: gmh@wdcc1.bnsc.rl.ac.uk
WORLD WIDE WEB                         http://www.theastronomer.org
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SUPERNOVA 2011B IN NGC 2655
Koichi Itagaki (Yamagata, Japan) reports the discovery on CBET 2625 of a 
possible magnitude 15.8 supernova on an unfiltered CCD image taken on 
2011 Jan. 7.431 UT with a 0.30-m reflector at Takanezawa, Tochigi. The 
new object was not detected on Itagaki's image of Jan. 2.447 (limiting 
mag 18.5), but it does appear at mag 17.5 on his image taken on Jan. 
5.570.  The object is located at:
RA 08h 55m 48.50s DEC +78 13' 02.7"(2000), which is 31.7"E and 21.4"S of 
the nucleus of the host galaxy, NGC 2655.
Itagaki's discovery image can be seen at:
http://www.k-itagaki.jp/images/psn2655.jpg.
Yamaoka adds that Ken-ichi Kadota, Japan confirmed 2011B at mag 15.9 on 
co-added images taken on Jan. 7.72UT with a 0.25-m reflector, from which 
he measured position end figures RA 48.03s, DEC 01.5".  Yamaoka also 
forwards a report from M. Koishikawa, Sendai Astronomical Observatory, 
who notes that 2011B is not visible on Jan. 3.735 UT (limit mag 19) with 
the SAO 1.3-m reflector.

An independent discovery has been made by Masaki Tsuboi on a 30-s 
unfiltered CCD frame limiting magnitude 17.5) taken on Jan. 8.459 UT 
using a 0.30-m reflector + CCD giving mag 15.7. His discovery image is 
posted at the following website URL:
http://ftenku.web.fc2.com/astrophoto/NGC2655110108-02.jpg.

Following an appeal by the Central Bureau, Dave Balam, Dominion 
Astrophysical Observatory, National Research Council of Canada et. al., 
report that a spectrogram of Jan. 8.42 UT with the 1.82-m Plaskett 
Telescope shows it to be a type-Ia supernova near maximum light. 
Cross-correlation with a library of supernova spectra using the 
"Supernova Identification" code (Blondin and Tonry 2007, Ap.J. 666, 
1024) indicates that 2011B is most similar to the type-Ia supernova 
1992bo a few days pre-maximum light.

Guy Hurst, Basingstoke reports that V photometry using the 0.61-m 
Cassegrain of the Sierra Stars network gives:
2011 Jan 26.60UT, 13.1V; Feb 1.34, 13.3V. Cross checking between a 
series of comparison stars suggests some values in catalogues are 
uncertain. Please e-mail the editor/patrol coordinator with your full 
estimates and comparison stars, instrumental details and date/time so 
these can be re-reduced as necessary.

Guy M Hurst