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An SN-Ia in a very faint dwarf galaxy

ATEL # 1950; A.J. Drake, A. Mahabal, S.G. Djorgovski, M.J. Graham, R. Williams (Caltech); A.D. Myers (UIUC); M. Catelan (PUC); E.C. Beshore, S.M. Larson (LPL); E. Christensen (Gemini Observatory);
on 5 Mar 2009; 1:39 UT
Distributed as an Instant Email Notice (Supernova)
Password Certification: Andrew J. Drake (

Subjects: Optical, Nova, Supernova, Transients

Further to Atel#1937, we confirm the discovery of a type Ia supernova with Palomar 200 observations. The CRTS discovery has the following parameters:

CSS090213:030920+160505 Discovery 2009-02-13 UT 03:45:55 RA 03:09:19.79 Dec 16:05:05.3 Type SN Ia

The spectrum of CSS090213:030920+160505 (taken on Feb 25th UT) shows this to be an SN-Ia, 12 days past maximum light with redshift z=0.031+/-0.006.

As noted in Atel#1937, a nearby 23rd magnitude object is seen in the NOAO deep ecliptic survey (limiting mag 24.2). If this is the host galaxy, at the SN's redshift it would have a mag Mr=-12.6. Alternatively, assuming the supernova was discovered at peak (as suggested by the spectrum), and that its peak is Mr=-19.3, a 23rd magnitude host galaxy would have Mr=-13.1. The two results are thus consistent within the redshift uncertainty. Improved astrometry for the supernova's position shows a clear offset between the SN and the faint NOAO object. Assuming the SN's redshift, the projected separation is ~1.6kpc. This offset is within the extent expected for a low mass dwarf galaxy of the observed brightness. However, a host galaxy below the limits of the NOAO images is also possible.

This discovery is very similar to SN 2008hp (ATEL#1856) and provides additional evidence for a higher than expected rate of SN in such low-mass galaxies.

For finding charts and discovery images please see:
Current candidate and confirmed SNe can be found here.

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R. E. Rutledge , Editor
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