CRTS Discovery of a very energetic Type IIn Supernova
ATel #2010; A..A. Mahabal, A. J. Drake, S. G. Djorgovski, M. J. Graham, R. Williams, W. Max-Moerbeck (Caltech); M. Catelan (PUC, Chile); E. C. Beshore, S. M. Larson, A. Gibbs, R. Kowalski, A. Boattini, R. Hill (LPL/UA); E. Christensen (Gemini Observatory); V. Mohan, A. N. Ramaprakash, A. K. Kembhavi (IUCAA);
on 10 Apr 2009; 22:45 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Ashish Mahabal (aam@astro.caltech.edu)
Subjects: Optical, Supernovae, Transient
The Catalina Real-time Transient Survey (CRTS) has spectroscopically
characterized CSS080928:160837+041626 (ATel 1768)
as a Type IIn SN at z~0.041
using the SMARTS 1.5m telescope using Observations
taken on March 27th UT with the following results:
The object was first marked as a transient by CRTS on 2008-09-28 (unfiltered
mag=17.7). It was also
present in the 2007-09-13 images, but blended with the brighter star nearby
and hence not detected as a transient. Palomar-Quest images from 2007-02-24 do
not reveal the presence of the SN.
GALEX data from 2008-06-05
shows a well-detected source at this location
(NUV 19.93+/-0.04, FUV 21.18+/-0.09). It was not seen in AIS images from
2004-05-17 indicating a brightening in NUV by at least 2.5 mags.
Coadded images from SDSS (all filters)
reveal the presence of a possible faint host at the location.
Assuming that the galaxy has r=23, at z=0.041
it translates to M_r=~-13, almost a 100 times dimmer than the LMC.
Palomar 60-inch (P60) data form 2009-03-21 reveals that it is still bright
(r=17.60+/-0.04). It has stayed bright for over 500 days, and rising much of
the time. In fact
the SMARTS spectrum with its Balmer lines (strong H-alpha, H-beta, H-gamma),
He I lines (5876, 7065 and possibly others), and an
absence of Oxygen lines reveals it to be much more like SN1994Y at T=30 days
(Filipenko A.V., ARAA, 1997, 35, 309-355, Fig. 14).
There is also some evidence
of Fe-I emission and the H-beta shows a P-Cygni like profile. The
maximum P60 r-band magnitude was ~17.2 suggesting an absolute magnitude
~-18.8. The evidence is consistent with a type IIn supernova possibly with
high density circumstellar material.
Additional observations are requested.
All current candidate and confirmed SNe as well as finding charts can be found
here.
