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PESSTO spectroscopic classification of optical transients

ATel #4851; Queen's University Belfast
on 3 Mar 2013; 17:04 UT
Credential Certification: Cosimo Inserra (c.inserra@qub.ac.uk)

Subjects: Optical, Supernovae

Referred to by ATel #: 4862, 4901

Nic Walton, Nadia Blagorodnova (IoA, Cambridge), Matt Nichol, Morgan Fraser, Cosimo Inserra (Queen's University Belfast), S. Benetti, A. Pastorello, (INAF - Padova Astronomical Observatory), S. Valenti (LCOGT/UCSB), S. Taubenberger (MPA Garching), S. J. Smartt, K. Smith, D. Young (Queen's University Belfast), M. Sullivan (University of Southampton), A. Gal-Yam, O. Yaron (Weizmann Institute for Science)

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 Tarot survey (http://tarot.obs-hp.fr/), the Tsinghua University - NAOC Transient Survey, 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 2013 Feb 2, 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  |  z     | Type  | Phase | Notes
PSN J06161835-2122329 | 06 16 18 35 | -21 22 32.9 | 20130226 | Tarot | 15.3 | 0.009 | II | ~0 | (1) PSN J12393328+1525520 | 12 39 33.28 | +15 25 52.0 | 20130222 | TNTS | 19.4 | 0.072 | SN | - | (2) SSS130221:133330-194457 | 13 33 30.00 | -19 44 56.7 | 20130221 | CRTS | 18.5 | 0.096 | IIn | - | (3)

(1) The transient has a blue, largely featureless continuum apart from a broad absorption at Halpha, similar to a young Type II SN. Narrow Halpha emission is also visible at the rest wavelength of NGC 2207, probably due to contamination from a nearby HII region.

(2) PSN J12393328+1525520 is at least 8 days old, and has a blue, featureless spectrum. The transient could be either a young SN within IC 3622, or a foreground CV. Although, no clear lines at z=0 have been identified.

(3) (3) SSS130221:133330-194457 has narrow (FWHM ~2000 km/s) Balmer lines in emission, together with HeI on a blue continuum. We find an excellent match to a template AGN spectrum at z=0.096. However, there is no galaxy visible in either the CRTS template image, or in archival DSS images. For a limiting magnitude ~21, this implies a quiescent galaxy magnitude fainter than -17.2, which is much fainter than typical for an AGN host. Moreover, no clear [OIII] lines (4959,5007Ang) are visible. Then, a plausible classification could be a Type IIn SN. However, in this scenario the emission line widths are broader than what is usually observed in an interacting transient.