Classification of AT2018bym as a Type I Superluminous Supernova
ATel #11714; P. Blanchard, S. Gomez, E. Berger, M. Nicholl (Harvard/CfA), S. Kattner, B. Weiner (MMTO)
on 13 Jun 2018; 23:24 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Peter Blanchard (pblanchard@cfa.harvard.edu)
Subjects: Optical, Supernovae
AT2018bym = ATLAS18ohj = MLS180520:184313+451228 = ZTF18aapgrxo was announced to the TNS by ATLAS (Tonry et al. 2011; ATel #8680) with a detection on 10 May 2018 UT and was detected even earlier by CRTS (Drake et al. 2009) on 5 May 2018 UT. We selected this event for spectroscopic follow up based on its ZTF data (Bellm & Kulkarni 2017; ATel #11266) as available through the ZTF Alert Archive (https://ztf.uw.edu/alerts/public/). An optical spectrum (covering 3800-9200 angstroms) obtained with Binospec on the MMT 6.5-m telescope on 9 June 2018 UT reveals that AT2018bym is a Type I superluminous supernova (SLSN) at z=0.274 (based on the presence of host galaxy [OIII] and H-alpha emission lines). At this redshift the spectrum is well matched to other Type I SLSNe near peak (e.g. PTF12dam; Nicholl et al. 2013). The absolute g-band magnitude in the latest ZTF data is about -21.9 AB mag. Additional follow-up observations are underway.