Spectroscopic Classifications of Optical Transients with SOAR

ATel #11865; Y.-C. Pan, R. J. Foley (UCSC), S. W. Jha (Rutgers), A. Rest (STScI), D. Scolnic (Chicago/KICP)
on 17 Jul 2018; 18:31 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Ryan Foley (foley@ucsc.edu)

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We report the following classifications of optical transients from spectroscopic observations with the Goodman spectrograph on the Southern Astrophysical Research (SOAR) telescope. Targets were supplied by the ATLAS and ASAS-SN. All observations were made on 2018 July 17 UT. Classifications were performed with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).

 
Name        | IAU Name  | RA (J2000)  | Dec (J2000)  |   z   | Type | Phase |  Notes
 
ASASSN-18oe | AT2018ddb | 00:02:49.71 | -66:11:06.14 | 0.029 |  Ia  |  +5 d | (1) 
ATLAS18rzu  | AT2018dhp | 21:32:51.41 | -25:20:24.00 | 0.031 |  II  |       | (2) 
ASASSN-18pg | AT2018dyb | 16:10:58.77 | -60:55:23.16 | 0.018 |  TDE |       | (3) 

Notes: When the redshift is given to 2 decimal places, it is derived from the SN spectrum. Otherwise, the redshift is determined from the host galaxy. (1) We measure a Si II 6355 velocity of -9,800 km/s (2) Blue and relatively featureless continuum. We identify a weak spectral feature that is consistent with H alpha at a velocity of -17,400. (3) Blue continuum with several spectral features. We identify some features as likely being He II 4686, H beta, He I 5876, and H alpha in emission. All lines have FWHM of ~12,000 km/s. Using a distance modulus of 34.4 mag to the host galaxy and correcting for MW extinction, the discovery magnitude corresponds to M = -18.5 mag, similar to other TDEs, but more luminous than most SNe II. From the confirmation image, the transient appears coincident with the nucleus of its host galaxy. Further follow-up observations are encouraged.