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A Recent Spectrum of SN2011ht

ATel #3895; Roberta Humphreys (University of Minnesota)
on 28 Jan 2012; 18:36 UT
Credential Certification: Roberta Humphreys (roberta@umn.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 4062

SN2011ht in UGC 5460 was first reported as possible supernova impostor (PSN J10081059+5150570) with Mv ~ -14 and a spectrum with Fe II absorption lines plus narrow hydrogen and Ca II emission with P Cygni absorptions by Pastorello et al. 2011 (CBET 2851). After its discovery, the object continued to brighten with a large and unusual increase in its UV flux (Roming et al, 2011 ATEL #3690). It was subsequently assigned a supernova designation based on its luminosity Mv ~ -17mag (Prieto et al. ATEL #3749). Its spectrum had also evolved with strong hydrogen emission with very broad wings and P Cygni absorption plus broad He I emission lines (Prieto et al 2011 CBET 2903). The absorption lines were gone. A paper is in preparation by Roming et al. describing the UV and optical light curve and spectra. A spectrum obtained on Jan 23, 2012 with the MMT/Hectospec and the 270 line grating with 5A resolution from 3650A to 9200 A shows another significant change. Its spectrum shows strong hydrogen, the Ca II triplet, Na I D, Fe II and [Fe II] emission lines with deep P Cygni absorptions. The H and Ca II emission lines have broad wings asymmetric to the red. The spectrum also has strong H and K absorption, a prominent G-band, very strong O I 7774A and 8446A absorption and other absorption lines characteristic of a late-F to early-G type supergiant. [Ca II] is not present in emission. I thank Perry Berlind and Mark Ammons for obtaining the spectrum in the Hectopsec queue.