[ Previous | Next | ADS ]

Discovery of an SN 2005gj-like supernova by CRTS

ATel #4081; A. J. Drake (Caltech), D. Garcia-Alvarez (IAC/GTC), S. G. Djorgovski, A. A. Mahabal, M. J. Graham, R. Williams (Caltech); J. Prieto (Princeton); M. Catelan (PUC Chile); E. Christensen (Gemini Obs); S. M. Larson (LPL/UA) plus the GTC and VSOP teams
on 30 Apr 2012; 23:05 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Andrew J. Drake (ajd@cacr.caltech.edu)

Subjects: Optical, Supernovae, Transient

On March 27.2UT CRTS discovered transient CSS120327:110520-015205 in data taken by the Catalina Sky Survey (CSS) Schmidt telescope (Drake et al. 2012, ATel#4011). Upon inspection of SDSS DR8 data a faint host galaxy was found with magnitudes u=20.7, g=19.7, r=19.3, i=19.1 and z= 18.9. The rising lightcurve of the event shows that the event began around 2012 Jan. 23 UT. Follow-up observations were taken with the Palomar 1.5m telescope in g, r, i and z on March 29.13UT, at which time the event had colours g-r=0.53, r-i=0.26 and i-z=0.04. Additional CSS observations of the object were taken on Apr. 15UT. The combined photometry appear to show some evidence for variability near peak brightness. However, additional analysis is required to constrain variability of the host galaxy.

Spectroscopic observations were taken with the Gran Telescopio CANARIAS (GTC) on April 17th with OSIRIS (range 370-785 nm). The spectrum shows features of type-Ia/Ic SNe along with broad and narrow Balmer features associated with type-IIn supernovae. The spectrum is a good match to past spectra of Ia/IIn CSM-interaction supernovae SN 2002ic and SN 2005gj (Aldering et al. 2006, Prieto et al. 2007) as well as hypernova candidate SN 1997cy (Germany et al. 2000). Based on narrow lines in the spectrum the supernova is at redshift z=0.09. After correcting for foreground reddening of Av=0.17, based on Schlegel et al. (1998, ApJ, 500, 525) extinction maps, the peak observed luminosity of the event is Mv~-20.5. This is significantly brighter than normal type-Ia events and consistent with both SN 2005gj (Aldering et al. 2006) and SN 1997cy (Germany et al. 2000). Further details and figures are provided at this link.

Additional follow-up is requested.