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ePESSTO spectroscopic classification of optical transients

ATel #12221; E. Congiu (Padova), M. Berton (FINCA), S. Benetti (Padova), A. Pastorello (Padova), A. Reguitti (Padova), T-W. Chen (MPE), R. Cartier (CTIO), A. Nyholm (OKC), C. Inserra (Southampton), E. Kankare (QUB), K. Maguire (QUB), S. J. Smartt (QUB), D. R. Young (QUB), O. Yaron (Weizmann), I. Manulis (Weizmann), J. Tonry (IfA, Univ. of Hawaii), L. Denneau (IfA, Univ. of Hawaii), A. Heinze (IfA, Univ. of Hawaii), H. Weiland (IfA, Univ. of Hawaii), B. Stalder (LSST), A. Rest (STScI), K. W. Smith (QUB), O. McBrien (QUB), D. E. Wright (Univ. of Minnesota)
on 16 Nov 2018; 14:10 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Andrea Pastorello (andrea.pastorello@oapd.inaf.it)

Subjects: Optical, Supernovae, Transient

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 classifications. Targets are supplied by the ATLAS survey (see Tonry et al. (2011, PASP, 123, 58) and Tonry et al., ATel #8680). Information on the targets was taken from the IAU TNS list (see https://wis-tns.weizmann.ac.il/).
All observations were performed with the ESO New Technology Telescope at La Silla on 2018 November 16 (UT), equipped with 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). The 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 |  Discovery Mag.  |    z     |  Type  |   Phase  | Notes 
ATLAS18ybz    | SN 2018hrn  | 21:31:33.84 | +23:00:53.08 | 2018-11-01.31  | ATLAS  | 18.56 (o-ATLAS)  |  0.060   | Ia     | post-max | (1) 
ATLAS18yzn    | SN 2018iif  | 00:43:41.34 | -08:10:56.56 | 2018-11-08.43  | ATLAS  | 18.98 (c-ATLAS)  |  0.201   | II-pec | +2 weeks | (2) 
ATLAS18yzv    | SN 2018iii  | 02:08:05.18 | +23:10:36.83 | 2018-11-09.47  | ATLAS  | 19.28 (c-ATLAS)  |  0.103   | Ia     | at max   | (3) 
ATLAS18ylx    | SN 2018idw  | 06:44:41.08 | -30:53:39.95 | 2018-11-07.63  | ATLAS  | 18.24 (c-ATLAS)  |  0.0369  | Ia     | post-max | (4) 
 
(1) The spectrum of SN 2018hrn, obtained on 2018-11-16.03 UT, is that of a Type Ia SN about 5-7 days after B-band maximum. The expansion velocity,  
inferred from the wavelength of the Si II 635.5 nm line, is 11000 km/s. Our classification agrees with the ZTF classification available in TNS  
Classification Report No. 3035. 
(2) A low signal-to-noise spectrum of SN 2018iif, obtained on 2018-11-16.12 UT, shows it to be a Type II SN. The spectrum is blue, with Balmer lines showing multi-component profiles. A narrow, unresolved Halpha feature sits on a broad component (with FWHM ~11000 km/s). A broad P Cygni profile is possibly detected for Hgamma, with the minimum blue-shifted by about 6500 km/s. The redshift of the faint host galaxy is inferred from the position of the narrow Halpha. Adopting a standard cosmology with H0 = 73 km/s/Mpc, we obtain a distance modulus of 39.88 mag. This gives a discovery absolute magnitude of about -20.5, and a current absolute magnitude of -20.7.
(3) The spectrum of SN 2018iii, obtained on 2018-11-16.18 UT, matches that of a Type Ia SN around the maximum light. The expansion velocity of the SN ejecta, obtained from the minimum of the Si II 635.5 nm line, is 11500 km/s. The redshift of the host galaxy, SDSS J020805.21+231037.2, is obtained from the position of the SN spectral features.
(4) The spectrum of SN 2018idw, obtained on 2018-11-16.19 UT, is that of a normal Type Ia a few days after maximum. The expansion velocity, inferred from the minimum of the Si II 635.5 nm line, is about 9700 km/s. The redshift of the host galaxy, ESO 427- G 001, is from Huchra et al. 2012, ApJS, 199, 26, and matches fairly well the value obtained from the SN spectral features.