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Discovery of a supernova ROTSE3 J115705+532955

ATel #1277; F. Yuan (U. Mich.), R. Quimby (Caltech), J. Aretakis, C. Akerlof (U. Mich.) and J. C. Wheeler (U. Texas) on behalf of the ROTSE collaboration; A. Rau (Caltech)
on 14 Nov 2007; 03:55 UT
Credential Certification: Fang Yuan (yuanfang@umich.edu)

Subjects: Optical, Nova, Supernovae

We report the discovery of a supernova, located at RA: 11:57:04.75 Dec: +53:29:55.3 (J2000 uncertainty <1") in unfiltered CCD images taken by the 0.45m ROTSE-IIIb telescope at McDonald Observatory, Texas. The supernova was discovered at 16.8 +/-0.1 mag on Oct 27.49 UT. It was observed to be decaying at a rate of ~0.05 mag/day and was at 17.7 +/-0.1 mag on Nov 13.46 UT. The magnitudes quoted above are unfiltered calibrated relative to USNO B1.0 R. There is a marginally detected r=22.9 host seen at the location of the SN in pre-explosion SDSS imaging. A finding chart of the supernova can be found at: http://www.rotse.net/transients/j1157+5329/j115705+532955.jpg

A quick reduction of the red channel (510-990 nm) spectra obtained on Nov 13.55 UT by A. Rau with the Palomar 200" telescope (+ Double Beam Spectrograph) shows it to be a type Ia at about 2 weeks past maximum light. Using spectra of SN 1994D as a template (Patat et al. 1996, MNRAS 278,111), we find an approximate redshift of z=0.035, which would imply an absolute magnitude fainter than about r=-13 for the SDSS host.