November 27, 2012: IAU Central Bureau Electronic Telegram 3314 (Daniel W. E. Green, ed.) announces the discovery by A. J. Drake, S. G. Djorgovski, M. J. Graham, A. Mahabal, and R. Williams (California Institute of Technology); R. H. McNaught (Australian National University); J. L. Prieto (Princeton University); M. Catelan (Pontificia Universidad Catolica de Chile); and S. M. Larson and E. Christensen (Lunar and Planetary Laboratory, University of Arizona) of a supernova in MCG -02-2-72 on 2012 November 18.52 UT at unfiltered magnitude 14.5, using Siding Spring Survey (SSS) images.
SN 2012gx was initially designated PSN J00380175-1351395 when it was posted on the Central Bureau's TOCP webpage (http://www.cbat.eps.harvard.edu/unconf/tocp.html).
Spectroscopy by N. Morrell, E. Hsiao, C. Contreras, and M. Phillips, Las Campanas Observatory, Carnegie Supernova Project, obtained on 2012 Nov. 20.05 UT with the Las Campanas 2.5-m du Pont telescope (+ WFCCD) indicates SN 2012gx is a Type-Ia supernova around 10 days past maximum brightness.
Additional CCD magnitudes for 2012gx include:
2012 July 19 UT, <18.9 (SSS);
2012 Nov. 19.131, 14.8 (R. A. Koff, Bennett, CO; position end figures 01.73s, 39.4"; image posted at http://antelopehillsobservatory.org/SNpictures/PSNJ00380175-1351395final.jpg);
23.096, 14.8 R (J. Brimacombe, Cairns, Australia; position end figures 01.70s, 39.5"; image posted at http://www.flickr.com/photos/43846774@N02/8221090003/);
24.225, 14.8 R (Brimacombe; position end figures 01.71s, 39.5"; image posted at http://www.flickr.com/photos/43846774@N02/8221090003/).
Coordinates: R.A. 00 38 01.75 Dec. -13 51 39.5 (2000.0)
SN 2012gx is offset 6.9" West and 18.5" North of the galaxy center.
Charts for SN 2012gx may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp).
Observations of SN 2012gx should be submitted to the AAVSO International Database using the name "SN 2012gx".
All information about SN 2012gx in this Special Notice is from CBET 3314.
Congratulations to all the members of the discovery team!
This AAVSO Special Notice was compiled by Elizabeth O. Waagen.
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