ePESSTO spectroscopic classification of optical transients

ATel #11943; E. Callis (UCD), R. Stein (HU Berlin/DESY), Z. Kostrzewa-Rutkowska (SRON/RU), M. Fraser (UCD), J. Lyman (Warwick), C. Inserra (Southampton), E. Kankare (QUB), K. Maguire (QUB), S. J. Smartt (QUB), O. Yaron (Weizmann), D. R. Young (QUB), I. Manulis (Weizmann), J. Tonry, L. Denneau., A. Heinze, H. Weiland (IfA, Univ. of Hawaii), B. Stalder (LSST), A. Rest (STScI), K. W. Smith, O. McBrien (QUB), D. E. Wright (Univ. of Minnesota)
on 12 Aug 2018; 17:03 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Morgan Fraser (morgan.fraser@ucd.ie)

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ePESSTO, the extended 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 ATLAS survey, see Tonry et al. (2011, PASP, 123, 58) and Tonry et al. (ATel #8680). All observations were performed on the ESO New Technology Telescope at La Silla on 2018 August 11, 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 and additional details can be obtained from http://www.pessto.org (via WISeREP) and the IAU Transient Name Server.

 
Survey Name | IAU Name  | RA (J2000)  | Dec (J2000) | Disc. Date | Source | Disc Mag | z     | Type     | Phase | Notes 
ATLAS18tim  | AT2018eue | 20:23:02.31 | -12:32:50.5 | 20180808   | ATLAS  | 19.6     | -     | -        | -     | (1) 
ATLAS18tjp  | SN2018evb | 22:51:02.71 | -03:38:58.1 | 20180808   | ATLAS  | 18.9     | 0.09  | Ia       | +0d   | (2) 
ATLAS18tcn  | AT2018ern | 19:44:43.63 | -14:48:24.5 | 20180806   | ATLAS  | 18.7     | 0?    | Stellar? | -     | (3) 
ATLAS18tcp  | AT2018erp | 22:32:55.15 | -03:02:49.8 | 20180806   | ATLAS  | 18.9     | 0.14  | AGN      | -     | (4) 
ATLAS18tem  | SN2018exv | 23:33:57.45 | -26:26:49.1 | 20180803   | ATLAS  | 18.6     | 0.07  | Ia       | +0d   | 
ATLAS18tgx  | AT2018est | 23:48:53.06 | -37:05:04.9 | 20180803   | ATLAS  | 18.0     | -     | CV       | -     | (5) 
ATLAS18tld  | SN2018evk | 23:15:44.95 | +06:54:39.7 | 20180805   | ATLAS  | 19.2     | 0.03  | II       | +2wk  | 
ATLAS18thf  | SN2018esx | 01:12:12.46 | -30:29:40.0 | 20180807   | ATLAS  | 19.2     | 0.09  | Ia       | +4d   | 

(1) Not visible on acquisition image.
(2) Previously classified by SCAT.
(3) The transient is dominated by narrow Balmer emission lines, however the continuum is remarkably flat. We measure a flux ratio between Halpha and Hbeta of 3.8. In addition, we see weak narrow emission features from He I. We also note that the transient may be associated with NGC 6822, a very nearby dwarf irregular galaxy. Given our spectral resolution and the small redshift for NGC 6882, we cannot determine whether ATLAS18tcn lies in this galaxy or the Milky Way.
(4) The spectrum has Balmer emission lines, He, and a blue component to the continuum consistent with an AGN. This is also consistent with the location of the transient in the nucleus of its host.
(5) Blue continuum with absorption in Hbeta and higher.