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THE ASTRONOMER Electronic Circular No 2743      2011 Jun 03 09.23UT
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 IN MESSIER 51
J. M. Silverman, A. V. Filippenko, S. B. Cenko (UC Berkeley) report on 
behalf of a larger collaboration (PTF) via The Astronomer's Telegram 
3398 the discovery of a new supernova in Messier 51. This object was 
independently discovered first by A. Riou and reported as PSN 
J13303600+4706330. PTF discoveries are made by autonomous PTF software, 
as well as by the Galaxy Zoo Supernova Project (Smith et al. 2011, 
MNRAS, 412, 1309; http://supernova.galaxyzoo.org ).

The object is located at:
RA 13h 30m 05.8s DEC +47 10 11.2 (2000)
It was recorded by PTF on June 1.19Ut at magnitude 13.5 though 
saturation made this measurement of brightness somewhat uncertain.

The spectrum shows a relatively blue continuum, with well-developed 
P-Cygni profiles in the Balmer series.  After removal of the host-galaxy 
recession velocity of 600 km/s (Rush, et al. 1996, ApJ, 473, 130), the 
minimum of the H-alpha absorption is blueshifted by about 17,600 km/s.

Robert Fidrich, Hungary, reports that unfortunately M51 was just outside 
of photos taken of V CVn on 30/31 May. He has checked
The co-added version of "g" pixels of 3x30s photos taken on May 25.745 
UT May 2011, but nothing was visible at the given position.

USNO-A2.0 1350-08287944 (~13.8V according to sky-map.org) was clearly 
visible, and USNO-A2.0 1350-08287671 was also above the detection limit 
(~14.7 according to sky-map.org), so the object was fainter than 
14.0-14.5V on 25/26 May.

Guy M Hurst