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THE ASTRONOMER Electronic Circular No 2763      2011 Aug 27 19.27UT
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 2011fe IN M101 (= PSN J14030581+5416254)

Further to the report on TA E-Circular 2762, the object is now designated as supernova 2011fe in CBET 2792.

S. B. Cenko (UC Berkeley) et al. in ATEL #3594 note that 2011fe is within ~8 arc sec of the published position (R.A. = 14:03:06.7, Decl. = +54:16:25) of a recorded nova in M101 (M101-1997-02) reported by Shafter et al. (2000, ApJ, 530, 193). However, after comparison with the original discovery image for the nova from 16 March 1997 UT with recent images of the supernova field, Cenko concludes that the nova and supernova are not spatially coincident and therefore the nova M101-1997-02 cannot be the progenitor of 2011fe.

In ATEL #3597, Laura Chomiuk (CfA/NRAO) & Alicia Soderberg (Harvard) report that EVLA radio observations yielded a non-detection of -5 +/- 6 microJy at the SN position. They note that no radio emission has ever been detected from a SN Ia, the majority of all core-collapse SNe within 10 Mpc are well detected in the radio band shortly after explosion, thus supporting the Ia classification for SN 2011fe.

In ATEL #3599, Howie Marion (Harvard) reports that observations with the IRTF 3.0m and the SpeX instrument on August 26.3 reveal that the spectrum shows strong absorption features from MgII at 13500 km/s. The CaII infrared triplet forms a strong and broad feature with a minimum at about 22000 km/s. SiII and OI are also detected at about 12500 km/s. The presence of evolved MgII features in this NIR spectrum is suggestive of a phase no more than one week before maximum light.

Selected recent CCD magnitude estimates: González Aug 26.872, +12.8C, Gavin  Aug. 26.854 +13.0C, Ayiomamitis  Aug. 26.938 +13.29C, Birtwhistle Aug 27.093, +13.00C, Brimacombe  Aug. 27.131 +13.3C.


Peter Birtwhistle (peter@birtwhi.demon.co.uk) a