[IAUC] CBET 3028: 20120222 : SUPERNOVA 2012ah IN NGC 7637 = PSN J23255963-8154333

Mie Feb 22 14:41:15 ART 2012

                                                  Electronic Telegram No. 3028
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2012ah IN NGC 7637 = PSN J23255963-8154333
     Greg Bock, Windaroo, Queensland, Australia, reports the discovery of an
apparent supernova (mag 14.8) by Stuart Parker (Oxford, Canterbury, New
Zealand) on unfiltered CCD images taken on Feb. 21.39 and 21.48 UT using a
35-cm f/6.3 Celestron C14 reflector (+ ST10 camera), with a confirming image
also taken by Roger Groom at Perth, Western Australia, on Feb. 21.51 using a
Meade 30.5-cm Schmidt-Cassegrain reflector (+ SBIG ST8XME camera).  The new
object is located at R.A. = 23h25m59s.63, Decl. = -81d54'33".3 (equinox
2000.0), which is 58" west and 8" north of the nucleus of the galaxy NGC
7637 (astrometry and photometry by Bock, using the USNO-B and UCAC3
catalogues).  Nothing is visible at this position on Digitized Sky Survey
red and infrared images (limiting red mag > 19); also, nothing is visible on
an unfiltered 30-s image of NGC 7637 taken by Stuart on Jan. 16 (limiting
red magnitude > 18.6).  The variable was designated PSN J23255963-8154333
when it was posted at the Central Bureau's TOCP webpage and is here
designated SN 2012ah based on the spectroscopic confirmation reported below.

     M. Dennefeld, Institut d'Astrophysique de Paris and University of Paris 6;
A. Rajoelimanana, P. Vaisanen, and H. Worters, South African Astronomical
Observatory (SAAO); A. Tekola, SAAO and Las Cumbres Observatory; and thirteen
students in the IAU's International School of Young Astronomers program (I.
Uba, Nigeria; F. Owayesy and C. Tumwine, Uganda; E. Christopher, Tanzania; P.
Simpemba, Zambia; and L. Catala, N. Madhanpall, S. Makhatini, Z. Mguda, R.
Ramphul, P. Skelton, D. Viljoen, and S. Wilson, South Africa) report that a
spectrum (range 363-734 nm, resolution 0.5 nm) of PSN J23255963-8154333 = SN
2012ah was obtained on Feb. 21.78 UT with the SAAO 1.9-m telescope (+ grating
spectrograph).  Comparison with a library of supernovae spectra via GELATO
(Harutyuyan et al. 2008, A.Ap. 488, 383) gives a best fit with a normal
type-Ia supernova close to maximum (e.g., SN 2000dk or SN 1989B).  Using the
Si II 635.5-nm absorption feature and a recession velocity of the galaxy NGC
7637 of 3700 km/s (Fairall and Jones 1991, Southern Redshift Catalogue,
University of Capetown), an expansion velocity of 10500 km/s is derived.


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                         (C) Copyright 2012 CBAT
2012 February 22                 (CBET 3028)              Daniel W. E. Green