Discovery of a New Supernova by the Palomar Transient Factory

ATel #2600; P. Nugent (LBNL), S. Bradley Cenko, A. M. Miller, D. Poznanski, J. S. Bloom, A. V. Filippenko (UC Berkeley), M. Sullivan (Oxford), D. A. Howell (LCOGT/UCSB), R. M. Quimby, E. O. Ofek, M. M. Kasliwal, S. R. Kulkarni (Caltech), N. M. Law (U. Toronto), R. G. Dekany, G. Rahmer, David Hale, R. Smith, J. Zolkower, V. Velur, R. Walters, J. Henning, K. Bui, D. McKenna (Caltech), and J. Jacobsen (LBNL)
on 6 May 2010; 22:14 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Peter Nugent (penugent@lbl.gov)

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On 2010 May 6.206 UT, data acquired with the Palomar Transient Factory Project (ATEL#1964) were reduced in nearly real-time by the automated subtraction pipeline at Lawrence Berkeley National Laboratory and the National Energy Research Scientific Computing Center. A source at position RA(J2000) = 12:49:22.81 and DEC(J2000) = -06:23:51.3 at a magnitude of 20.2 in R-band (calibrated with respect to the USNO catalog) was identified at May 6.315 by an autonomous inspection code which classified the source as a likely supernova, marking up the source as PTF10guz. Nothing was seen at this location to a 3-sigma limiting magnitude of 20.6 on May 3.202 UT. Robotized follow-up imaging with the Palomar 60-inch telescope and PAIRITEL was triggered upon the autonomous discovery. A spectrum was obtained using the Low-Resolution Imaging Spectrometer (LRIS; Oke et al. 1995, PASP, 107, 375) on the Keck I 10-m telescope at May 6.335, revealing the source to be a peculiar Type Ia supernova at a redshift z of 0.18, near peak brightness. The spectrum is similar to that of SNLS-03D3bb and SN 2006gz, indicating that this SN may belong to the class of Type Ia supernovae that are suspected to arise from super-Chandrasekhar mass progenitors: it has little Ca II (and the blue Ca II feature is narrow), and evidence for C II. In addition, the host galaxy is undetected to a limiting magnitude of 23.1 in co-additions of prior imaging from PTF. At z = 0.18, the SN is approximately at absolute magnitude -19.7 (the host being fainter than -16.6), but based on the blueness of the spectrum and its features, it may not yet have reached maximum light.