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Discovery of a Luminous Supernova, PTF10cwr

ATel #2492; R. M. Quimby, S. R. Kulkarni, E. Ofek, M. M. Kasliwal, D. levitan (Caltech), A. Gal-Yam (Weizmann Institute), S. B. Cenko (Berkeley) on behalf of the PTF Collaboration
on 20 Mar 2010; 02:40 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Robert Quimby (quimby@astro.as.utexas.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 2504, 2508

We report the independent discovery of an optical transient, PTF10cwr (a.k.a. CSS100313:112547-084941; Mahabal et al. ATel #2490), in R-band images obtained with the 1.2-m Oschin telescope at Palomar Observatory in the course of the Palomar Transient Factory survey (Law et al., 2009; Rau et al., 2009). The transient is located at RA = 11:25:46.67, DEC = -08:49:41.2 (J2000). On March 13.25 UT, the object was twice detected at about 18.8 mag. No object was seen at this location on March 4.27 UT to a limit of 20.4 mag. We additionally detected PTF10cwr on March 5, 12, and 16 UT.

Spectra (320-1000 nm) obtained with the 5.1-m Palomar telescope (+DBSP) on March 18.27 UT show that PTF10cwr is a luminous supernova similar to SN 2005ap (Quimby et al. 2007). We detect narrow Mg II absorption, and narrow emission lines from OII, OIII, and H-alpha (all presumably from the host), from which we derive a redshift of z=0.23. We do not confirm the redshift reported by Mahabal et al. (ATel #2490). In addition to the blue continuum, we detect broad features consistent with the OII multiplet (see arXiv:0910.0059).

We requested Swift UVOT observations, which were carried out between March 19.13 and March 19.27 UT. PTF10cwr is well detected:

   MJD   Filter   Mag   Mag_err  
55274.23  UVW1   17.70   0.04  
55274.21  UVM2   18.29   0.05  

Additional observations are underway. We thank the Swift team for promptly scheduling the ToO observations.