KAIT Discovery and Robotic Follow-up of a young SN Ia in NGC4424
ATel #4115; S. B. Cenko, A. V. Filippenko, J. M. Silverman, M. Kandrashoff (UC Berkeley), A. Gal-Yam (Weizmann Institute of Science), L. Pei, M. Nguyen, D. Carson, and A. J. Barth (UC Irvine):
on 18 May 2012; 17:00 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: S. Bradley Cenko (cenko@astro.berkeley.edu)
Subjects: Optical, Supernovae, Transient
We report the discovery with the Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory of a possible new supernova in the nearby (d = 15 Mpc; Cortes et al. 2008, ApJ, 683, 78) galaxy NGC 4424. The new object, dubbed PSN J12271283+0925132 (by the IAU), is located at (J2000.0) coordinates RA: 12:27:12.83, Dec: +09:25;13.2.
Following discovery on an unfiltered image obtained at 5:21 UT on 2012 May 17, KAIT autonomously began a sequence of triggered follow-up observations in the U, B, V, and clear (roughly R) filters beginning only 3 minutes later. Using stars from the USNO-B1 catalog for reference, we measure an R-band magnitude at this time of R = 16.9. Previous KAIT imaging on 2012 May 12 revealed no emission at this location to a limiting magnitude of R > 18.5.
A CCD spectrum (range 340-800 nm) obtained on May 18 UT with the Kast double spectrograph on the Shane 3-m telescope at Lick Observatory shows that the object is probably a very young Type Ia supernova. The spectrum resembles that of SN 1990N about two weeks before maximum brightness (Leibundgut et al. 1991, ApJ, 371, L23).
Intensive follow-up observations at all wavelengths are encouraged.
