Spectroscopic classification of 3 transients with Keck and DEIMOS.
ATel #14027; G. Terreran, P. K. Blanchard (Northwestern University), M. Berton (FINCA/MRO), K. Paterson, C. D. Kilpatrick, D. L. Coppejans (Northwestern University)
on 18 Sep 2020; 01:01 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Giacomo Terreran (giacomo.terreran@northwestern.edu)
Subjects: Optical, AGN, Supernovae
We report the spectroscopic classification of 1 supernova and 2 AGN, discovered by ATLAS (Tonry et al. 2016; ATel #8680), the Pan-STARRS Survey for Transients (PSST; Chambers et al. arXiv:1612.05560; Huber et al. ATel #7153) and the YSE collaboration (Jones et al. ATel #13330)
The observations were performed with the DEep Imaging Multi-Object Spectrograph (DEIMOS) mounted on the 10-m Keck II telescope (range 400-900 nm; resolution 0.35 nm).
Survey Name | IAU Name | Discovery MJD | Discovery mag | z | Type | Phase | Notes
ATLAS20xqi | SN 2020rmv | 59077.50 | 19.5 | 0.27 | SLSN-I | near peak | (1)
PS20gxa | AT 2019aafl | 58508.25 | 22.01 | 0.811 | Type-I AGN | - | (2)
PS20eor | AT 2020nso | 59027.57 | 21.13 | 0.563 | Type-I AGN | - | (3)
(1) SN 2020rmv was first reported by ATLAS on 2020-08-16.5 (MJD 59077.5) but the Zwicky Transient Facility (Kulkarni ATel #11266) reported later a first detection on 2020-07-31 (MJD 59061.43). The lightcurve shows a rise-time of 50~d. The spectrum shows strong similarities with Type I SLSNe before peak, in particular SN 2015bn (Nicholl et al. 2016). We derive an approximate redshift of z ~ 0.27 through a comparison of SN features with SN 2015bn as there are no detected host emission lines, implying a current absolute r-band magnitude of M_r ~ -21.6.
(2) Forced photometry on last year images of this transient show a remarkably long rise-time of 576 days (AstroNote 2020-168). Our spectrum shows emission from a broad Mg II 2796,2803 doublet, [O II] 3727, and [O III] 5007 all at redshift of 0.811, consistent with being a Type I AGN.
(3) The spectrum shows emission from a broad Mg II 2796,2803 doublet, [O II] 3727, and [O III] 5007 all at redshift of 0.563, consistent with being a Type I AGN.
