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THE ASTRONOMER Electronic Circular No 3078      2015 May 17 19.29UT
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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POSSIBLE EXPLOSION OF SN IMPOSTOR in NGC 2770
A. de Ugarte Postigo, IAA-CSIC and others report on ATEL 7514 their
monitoring of the SN imposter in NGC 2770 with the 1.5m and 0.9 m telescopes
at Sierra Nevada Observatory (Granada, Spain). An observation obtained on
2015 May 15 (20:45 UT) shows that the transient (also known as PSN
J09093496+3307204 and SNhunt275) has brightened to R = 16.0 mag,
corresponding to an absolute magnitude of M_R = -16.4 mag. The transient was
more than 2 magnitudes fainter in images obtained 9 days before. This
suggests it is experiencing an evolution similar to SN 2009ip in 2012
August/September 2012 and that it is possible that the progenitor star has
exploded. They encourage observations at all wavelengths.

Quite independently Ron Arbour, South Wonston, England discovered the
outburst during a UK Nova/Supernova Patrol on May 16.94UT but had also
recorded it earlier on 4 occasions when it had been included in a new master
image of the galaxy. 
Position: RA 09h 09m 35.11s DEC +33° 07' 22.2" (2000)
Offsets from galaxy:   18" E   4" S
Mag. 16.0 V  (unfiltered)
This appears to be at the same position as the object reported in ATel #7042
by N. Elias-Rosa et.al and designated a SN Imposter.
It was originally found on 2015/02/07.390 by the CRTS.
Earlier follow-up observations by S.Howerton produced magnitudes as follows:
2015/02/08.14    19.9
2015/02/10.16    20.3
2015/02/19.26    19.4

G. Duggan, Caltech and others obtained a spectrum with the Keck I telescope.
They saw a hot, blue continuum with prominent Balmer, Helium II and Helium I
emission with peak redshifts consistent with the velocity of NGC2770. The
H-alpha line is asymmetric and not Gaussian with an approximate full width
half maximum of ~1200 km/s.  Note that this transient was flagged in the
intermediate Palomar Transient Factory database during a previous eruption
in 2013 and designated as iPTF13efv.

Guy M Hurst