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THE ASTRONOMER Electronic Circular No 2320      2007 Mar 28 08.50UT
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 2007ax IN NGC 2577
On March 22, we received an e-mail from Ron Arbour of Pennell 
Observatory, South Wonston, England reporting his discovery of a further 
possible supernova, this time in NGC 2577.

It was recorded on an unfiltered CCD image taken on 2007 Mar 21.9776UT 
at magnitude 17.2 using a 0.4-m f/5 Newtonian and Starlight Xpress CCD 
camera in the course of searches for the UK Nova/Supernova Patrol. The 
object appeared on several subsequent images to a limiting unfiltered 
magnitude of about 19.0.

Ron has measured the precise position as:
RA 08h 22m 43.26s DEC +22 33'16.9" (2000)
Offsets from galaxy: 2.6"W  5.5"N

The object is not visible on the Digitised Sky Survey POSS II Blue
plate (1997 Mar 9) or the POSS II Red plate (1993 Dec 9) nor is it 
listed on CBAT's Minor Planet Checker. The object is also not present on 
Ron's images of NGC 2577 taken on 2007 Jan. 23.893UT and Mar. 9.959UT 
with limiting unfiltered magnitude about 19.0.

Denis Buczynski, Lancaster, England reports confirmation of the new 
object which he recorded on Mar 22 at 23hUT using a 0.60-m f/3 AltAz 
Newtonian + SBIG ST7XME (unfiltered) in 8 x 15s exposures.

In CBET 907, S. Blondin, M. Modjaz, R. Kirshner, and P. Challis, 
Harvard-Smithsonian Center for Astrophysics; and T. Matheson, National 
Optical Astronomy Observatory, report that a spectrogram obtained by M. 
Calkins on Mar. 26.21 UT with the F. L. Whipple Observatory 1.5-m 
telescope (+ FAST), shows it to be a
type-Ia supernova around maximum light.  Cross-correlation with a
library of supernova spectra indicates that 2007ax is most similar to 
the subluminous type-Ia supernova 1991bg at 3 days past maximum.
Adopting a recession velocity of 2074 km/s for the host galaxy, the 
maximum absorption in the Si II line (rest 635.5 nm) is blueshifted by 
roughly 10000 km/s.  Assuming that the galaxy is in the Hubble flow and 
that the supernova suffers negligible extinction, the discovery 
magnitude of 17.2 corresponds to an absolute magnitude of roughly -15, 
which is roughly 2 magnitudes fainter than SN
1991bg at the same phase.

Hitoshia Yamaoka, Japan also reports that K. Itagaki, Japan recorded it 
at mag about 16.4 on an unfiltered CCD image taken on Mar. 23.499 UT. 
Nothing is obviously visible on his image of Mar. 17.636 to a limit of 
approximately magnitude 17.0.

No IAUC has so far been issued but a preliminary announcement has 
appeared on CBET 904. Congratulations to Ron on his 18th supernova 
discovery.

SUPERNOVA 2007av IN NGC 3279
Further to the discovery note on TA E-Circular 2319, a note has appeared 
on CBET 903 in which A. Harutyunyan et. al., Istituto Nazionale di 
Astrofisica, Osservatorio Astronomico di Padova; and V. Lorenzi 
Telescopio Nazionale Galileo (TNG), have reported that a spectrum of SN 
2007av obtained on Mar. 22.86UT with the 3.5-m TNG shows it to be a 
type-II supernova caught a few days after explosion.
Guy M Hurst