Supernova Discovery from the Palomar Transient Factory

ATel #1964; S. Kulkarni (Caltech), N. Law (Caltech), M. Kasliwal (Caltech), R. Quimby (Caltech), E. Ofek (Caltech), P. Nugent (LBNL), I. Arcavi (Weizmann), L. Bildsten (KITP/UCSB), J. Bloom (Berkeley/LCOGT), J. Brewer (Berkeley), T. Brown (LCOGT), S. B. Cenko (Berkeley), D. Ciardi (IPAC), E. Croner (COO), R. Dekany (COO), G. Djorgovski (Caltech), A. V. Filippenko (Berkeley), D. Fox (Penn State), A. Gal-Yam (Weizmann), C. Grillmair (IPAC), D. Hale (COO), N. Hamam (IPAC), D. Helfand (Columbia), G. Helou (IPAC), I. Hook (Oxford), A. Howell (LCOGT/UCSB), J. Jacobsen (LBNL), M. Kiewe (Weizmann), R. Laher (IPAC), A. Mahabal (Caltech), S. Mattingly (IPAC), J. Patterson (Columbia), H. Perets (Weizmann), S. Perlmutter (LBNL), A. Pickles (LCOGT), D. Poznanski (Berkeley/LBNL), A. Rau (Caltech), G. Rahmer (COO), W. Reach (IPAC), W. Rosing (LCOGT), M. Shara (Columbia), R. Smith (COO), D. Starr (LCOGT), M. Sullivan (Oxford), J. Surace (IPAC), R. Thomas (LBNL), and V. Velur (COO)
on 12 Mar 2009; 03:29 UT
Credential Certification: Robert Quimby (quimby@astro.as.utexas.edu)

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The Palomar Transient Factory (PTF) has discovered an optical transient located at RA = 14:23:55.82 Dec = +35:11:05.2 (J2000, uncertainty <1"), in g-band images taken with the CFH12K camera mounted on the 1.2-m Oschin telescope at Palomar Observatory. The transient was detected at 18.62 +/- 0.04 mag on March 2.347 UT after subtraction of a reference template made from PTF images acquired on Feb 25, 26, and 28. Note that this reference template may contain some light from this rising transient and the magnitudes reported here may correspond to lower limits in flux. The transient is offset 0.9" W and 2.7" S from the core of an SDSS galaxy with g=17.78 and a redshift of z=0.0555.

We obtained spectra (330-870 nm) of the transient on March 8.388 UT with the 5.0-m Palomar Hale telescope (+ Double Beam Spectrograph). These data reveal the transient to be a normal Type Ia supernova at a redshift consistent with the apparent SDSS host. In this restframe, the expansion velocity derived from the minimum of the Si II (rest 635.5 nm) line is about 10,700 km/s. The best match found with the Superfit SN spectral identification code (Howell et al. 2005, ApJ, 634, 1190) is to SN 1994D around 1 week prior to maximum light.

We further report the independent detection of SN 2009an (CBET 1707, 1709) in PTF data obtained on March 2.255 UT. This source is very clearly present in our reference data, but is significantly brighter in the March 2 data.

PTF is a fully-automated, wide-field survey aimed at a systematic exploration of the optical transient sky. The program is centered on a 12Kx8K, 7.8 square degree CCD array (CFH12K) re-engineered for the 1.2-m Oschin Telescope at Palomar Observatory by COO (Rahmer et al. 2008). Photometric follow-up is undertaken by the automated Palomar 1.5-m telescope (Cenko et al. 2006) and other facilities provided by consortium members. PTF uses eighty percent of the 1.2-m and fifty percent of the 1.5-m telescope time. With an exposure of 60-s the survey reaches an approximate depth of m_R=20.5 and m_g'=21. Two major experiments are planned for the five-year project: 1) a 5-day cadence supernova search and 2) an exotic transient search with cadences between 90 seconds and 1 day. PTF provides automatic, real-time transient classification and follow-up, as well as a database including every source detected in each frame. PTF is a collaboration of Caltech, LBNL, IPAC, Berkeley, LCOGT, Oxford, Columbia and the Weizmann Institute. First light was achieved 13 Dec 2008. Sources were found by searching a single night of data from a one-day-cadence experiment ongoing since Feb 18 2009. This night covered 589 square degrees on the sky. Transient candidates produced by the subtraction pipeline at NERSC were vetted by human scanners.