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Discovery of a Type II Supernova ROTSE3 J012520+085413

ATel #1217; F. Yuan, J. Aretakis, C. Akerlof (U. Mich.) and R. Quimby (Caltech)
on 15 Sep 2007; 22:23 UT
Credential Certification: Fang Yuan (yuanfang@umich.edu)

Subjects: Optical, Nova, Supernovae

We report the discovery of a supernova, located at RA: 01:25:20.1, Dec: 08:54:13 (J2000) in unfiltered CCD images taken by the 0.45m ROTSE-IIIb telescope at McDonald Observatory, Texas. The supernova was detected at 19.0 +/- 0.4 mag on Sep 8.24 UT and at 18.6 +/- 0.1 mag on Sep 14.23 UT. Note that it was blended with a nearby 16.2 mag USNO star in the ROTSE images. It was not detected to a limiting magnitude of ~19.0 in images taken on Sep 7.95 UT by ROTSE-IIIc at the H.E.S.S. site at Mt. Gamsberg, Namibia. Magnitudes quoted above are unfiltered calibrated relative to USNO B1.0 R. A finding chart of the supernova can be found at: http://www.rotse.net/transients/j0125+0854/070914_012520+085413.jpg.

R. Quimby adds a spectrum (420-890 nm) of the SN obtained on Sep. 15.28 UT with the 9.2m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by M. Shetrone, V. Riley, and F. Deglman shows it to be a Type II. Emission lines from H-alpha, -beta, and -gamma are detected, and a redshift of z=0.09 is inferred from the line peaks. Weak emission lines from HeII 468.6-nm and possibly OIII 500.7-nm are also seen. An emission peak is observed at rest 588-nm, which, if identified with NaI, would imply a blueshift relative to the Balmer lines of ~600 km/s.