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PESSTO spectroscopic classification of optical transients

ATel #8437; R. Le Breton, L. Le Guillou (LPNHE), M. Fraser (Cambridge), K. Maguire (QUB), R. Cartier (Southampton), Annalisa De Cia (Wiseman), Ilan Manulis (Weizmann), I. Arcavi (LCOGT), C. Inserra (QUB), E. Kankare (QUB), S. J. Smartt (QUB), K. W. Smith (QUB), M. Sullivan (Southampton), S. Valenti (UC Davis), O. Yaron (Weizmann), D. Young (QUB), L. Wyrzykowski,(Warsaw Observatory, Poland), D. Wright (QUB), K. Chambers, H. Flewelling, M. Huber, E. Magnier, J. Tonry, C. Waters, R. J. Wainscoat (IfA, Univ. Hawaii).
on 18 Dec 2015; 19:17 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Morgan Fraser (mf@ast.cam.ac.uk)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 8570, 9202

PESSTO, the Public ESO Spectroscopic Survey for Transient Objects (see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org ), reports the following supernova classifications. Targets were supplied by the OGLE-IV Real-time Transient Search (Wyrzykowski et al., 2014 arxiv:1409.1095; http://ogle.astrouw.edu.pl/ ), the Pan-STARRS Survey for Transients (see Huber et al., ATel #7153) and the MASTER Global Robotic Net (Lipunov et al., 2010, Adv. in Ast., 1-7). All observations were performed on the ESO New Technology Telescope at La Silla on 2015 December 17, 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
MASTERJ141023.42-431843.7 | 14:10:23.41 | -43:18:43.7 | 2015-12-15 | MASTER | 14.40 | 0.006 | Ib | ~0d | (1) OGLE15xl | 04:20:53.44 | -73:36:20.1 | 2015-11-08 | OGLE | 21.14 | 0.19 | ?? | ?? | (2) OGLE15xt | 03:24:50.23 | -66:32:36.3 | 2015-12-11 | OGLE | 20.60 | 0.11 | Galaxy | - | (3) PS15dcw | 08:46:36.42 | +06:43:26.7 | 2015-12-05 | PSST | 19.30 | 0.08 | Ia | +5d | PS15dlq | 10:54:24.69 | +06:34:32.7 | 2015-12-09 | PSST | 20.66 | 0.14 | Ia | ~0d | PS15dmp | 10:23:03.86 | -01:56:49.4 | 2015-12-13 | PSST | 19.91 | 0.14 | Ia | ~0d |

(1) Abs. mag ~-17.3, the SN lies within the face on spiral galaxy NGC 5483.
(2) The lightcurve of OGLE15xl shows a ~1 month rise to a peak magnitude of 19.9. The spectrum is blue, with clear broad features. Narrow emission lines are present, which are consistent with Halpha and [Oii]3727 at a redshift of z=0.19. The absolute magnitude of the transient at this redshift is ~-20. Preliminary astrometry indicates the transient is offset by ~2 pixels (0.5") from the nucleus of the host in OGLE difference images. Given the OGLE data, this offset is probably significant, however we note that the spectral and photometric properties are potentially consistent with a Tidal Disruption Event, where the broad feature in the blue could be HeII 4686. We also find a good spectral match to the superluminous SN PTF09cnd.
(3) The OGLE data show a source, offset from the nucleus of the galaxy, and present on two separate epochs. Two traces are visible on the two-dimensional spectra and both appear to be passive galaxies.