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Spectroscopic classification of two superluminous supernovae

ATel #8790; R. Chornock, K. Bhirombhakdi, R. Katebi (Ohio University), P. Blanchard, M. Nicholl, E. Berger (Harvard/CfA)
on 9 Mar 2016; 00:11 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Matt Nicholl (matt.nicholl@cfa.harvard.edu)

Subjects: Optical, Supernovae, Transient

We obtained optical spectra (range 4000-9000 Angstroms) of two apparently hostless transients reported by the Pan-STARRS Survey for Transients (PSST; Huber et al., ATel #7153). Observations were carried out on 2016 March 2-3 UT using the 2.4 m Hiltner Telescope and OSMOS at MDM Observatory. Classifications are reported below:

Name | RA (J2000) | Dec (J2000) | Disc. Date | Disc. Mag | Filter | Type | z | Notes
AT 2016ard | 14 10 44.55 | -10 09 35.4 | 20160216 | 18.75 | i | SLSN-I | 0.20 | (1)
AT 2016aps | 10 19 02.17 | +74 42 24.6 | 20160222 | 18.11 | i | SLSN-II ? | 0.265 ? | (2)

(1) Also known as PS16aqv and CSS160216:141045-100935. Spectrum shows a blue continuum with absorption features closely matching the O II lines in young Type I SLSNe at z=0.20. At this distance, the absolute magnitude at the PSST discovery is -21.1. Non-detections from PSST 10 days before discovery, and CSS photometry between February 16 and March 2, suggest the SN is rising or around maximum.
(2) Also known as PS16aqy. Spectrum shows a mostly featureless blue continuum, with one fairly weak emission feature near 8305 Angstroms having a FWHM of ~2000 km/s. If this line is H-alpha, we derive a redshift of 0.265, implying an absolute magnitude of -22.3. There is an i-band non-detection 30 days before discovery.