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Pan-STARRS1 MDS Early Discovery of a SN Ia in UGC 7228

ATel #3997; R. Chornock, G. H. Marion, M. Calkins (Harvard-Smithsonian Center for Astrophysics), R. Kotak, L. Magill, S. J. Smartt, K. Smith, M. Fraser (Queen's University, Belfast), C. Leibler, R. J. Foley, E. Berger, R. P. Kirshner, G. Narayan, A. M. Soderberg, C. Stubbs (CfA), A. Rest (Space Telescope Science Institute), M. Huber, J. Tonry (Institute for Astronomy, Hawaii), A. Riess (Johns Hopkins), W. M. Wood-Vasey (Pitt), E. Magnier, K. Chambers, N. Kaiser, J. Morgan, W. Burgett, J. Heasley, W. Sweeney, C. Waters, H. Flewelling (IfA), and P. A. Price (Princeton)
on 23 Mar 2012; 19:59 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Ryan Chornock (rchornock@cfa.harvard.edu)

Subjects: Optical, Supernovae, Transient

We report the early discovery and spectroscopic confirmation of a low-redshift type Ia supernova (designated PS1-12rg) in the galaxy UGC 7228 (cz=7568 km/s; Falco et al. 1999, PASP, 111, 438) by the Pan-STARRS1 Medium Deep Survey. The object was first detected on 2012 March 11.50 UT at the coordinates

RA = 12:13:37.309 Dec = +46:29:00.48 (J2000)

with an approximate brightness of zP1=22.8 mag (AB) and rose to iP1=16.99 mag by 2012 March 21.47. A spectrum (range 480-940 nm) obtained on March 15 using the R300R grism on OSIRIS with the GTC identified the object as a young normal SN Ia. An additional spectrum (range 350-740 nm) was obtained on March 23 with the 1.5-m telescope at the Fred L. Whipple Observatory on Mount Hopkins, Arizona. Cross-correlation of the March 23rd spectrum with a library of supernova spectral templates using the SNID code of Blondin and Tonry (2007, ApJ, 666, 1024) gives a best-fit age of about a week before maximum light. The velocity of the absorption minimum of Si II 635.5 nm is 10,800 km/s.

This discovery was made possible by the PS1 system operated by the PS1 Science Consortium and its member institutions ( http://www.ps1sc.org/PS1_System_ATel.shtml ). We thank the telescope operators of the PS1, GTC, and FLWO telescopes for their support.