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PESSTO spectroscopic classification of optical transients

ATel #4299; S. J. Smartt, C. Inserra, M. Fraser, D. Wright, D. R. Young (Queens University Belfast), A. Pastorello, S. Valenti (INAF-Osservatorio Astronomico di Padova), S. Taubenberger (MPA), M. Sullivan (University of Oxford), A. Gal-Yam, O. Yaron (Weizmann Institute for Science), G. Pignata (Universidad de Chile), S. Howerton (Arkansas City, KS, USA), C. Baltay, N. Ellman, E. Hadjiyska, R. McKinnon, D. Rabinowitz (Yale University), U. Feindt, M. Kowalski (Universitat Bonn), P. Nugent (LBL Berkeley)
on 8 Aug 2012; 15:03 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Morgan Fraser (mfraser02@qub.ac.uk)

Subjects: Optical, Star, Supernovae, Transient, Variables

Referred to by ATel #: 4329, 4346

PESSTO, the Public ESO Spectroscopic Survey for Transient Objects (see Valenti et al., ATel #4037; http://www.pessto.org ), reports the following supernova classifications. Targets were supplied by the La Silla-Quest survey (see Hadjiyska et al., ATel #3812), the Chilean Automatic Supernova Search (http://www.das.uchile.cl/proyectoCHASE/) and the Catalina Real-time Transient Survey (http://crts.caltech.edu/). All observations were performed on the ESO New Technology Telescope at La Silla on 2012 August 7, using EFOSC2 and Grism 13 (3985-9315A, 18A resolution). Classifications were done with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024) and GELATO (Harutyunyan et al., 2008, A&A, 488, 383). Classification spectra can be obtained from http://www.pessto.org (via WISeREP).

Name | RA (J2000) | Dec (J2000) | Disc. Date | Disc. source | Disc. Mag | Redshift | Type | Phase | Notes
LSQ12drz | 16:48:17.42 | +19:17:23.3 | 20120723 | LSQ | 19.1 | 0.137 | SN Ia | +9d | Normal, match to 92A
LSQ12eeq | 20:52:49.01 | -16:33:36.4 | 20120728 | LSQ | 19.0 | - | stellar | - |
PSNJ21253403-4016432 | 21:25:34.02 | -40:16:43.3 | 20120625 | CHASE | 15.5 | 0.017 | SN Ia | +33d | Normal, match to 03du
PSNJ20032484-5557192 | 20:03:24.84 | -55:57:19.2 | 20120627 | CHASE | 14.5 | 0.015 | SN Ia | +35d | Normal, match to 94ae
LSQ12ecb | 22:31:10.75 | -24:53:15.0 | 20120726 | LSQ | 18.2 | 0.089 | Galaxy | - |
LSQ12ecu | 23:46:09.17 | -19:21:27.4 | 20120730 | LSQ | 18.8 | 0.006 | HII region | - |
SNhunt144 | 21:12:08.91 | -47:03:14.0 | 20120806 | CRTS | 16.8 | 0.028 | SN Ia | -5d | Normal, match to 02bo
LSQ12dyw | 23:29:24.82 | -07:23:20.4 | 20120717 | LSQ | 19.4 | 0.09? | SN Ic-pec? | pre-max? | See note (1)
LSQ12ecp | 01:27:01.66 | -17:21:55.8 | 20120730 | LSQ | 18.0 | 0.077 | SN Ia | +18 | Normal, match to 03du
LSQ12dlf | 01:50:29.78 | -21:48:45.4 | 20120710 | LSQ | 18.8 | 0.23? | SN Ic-pec? | max? | See note (2)
LSQ12dvr | 02:38:16.32 | -02:26:19.0 | 20120723 | LSQ | 17.6 | - | stellar | - |

(1) LSQ12dyw rises by 0.8 mag over two weeks, and has a blue continuum in our EFOSC2 spectrum. A narrow, low signal-to-noise, emission feature at 7168A could be Halpha, which would place the transient at a redshift of z=0.09. Apart from this, the spectrum displays shallow, unidentified absorption features. A nearly featureless blue continuum at +2 weeks is similar to what is seen in ultra-luminous Type I SNe (Quimby et al., 2011, Nature 474, 487). We note, however, that at z~0.09 the absolute magnitude of the SN is only -19.5, and so the SN may still be pre-maximum.

(2) LSQ12dlf has a blue continuum, with apparent broad absorption features. The host galaxy is extremely faint, and is not detected in the La Silla Quest reference stacks. At a redshift of 0.23 (estimated from the best match to a Type Ic spectrum via SNID), the transient would an absolute magnitude of -21.5. This high luminosity, coupled with a blue colour, a slow rise time and a faint host is reminiscent of the family of ultra-luminous Type I SNe (Quimby et al., 2011). If this is the case, then we suggest that it may soon undergo a transition to resemble a Type Ic SN (Pastorello et al. 2011, ApJ, 724, 16)