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Spectroscopic Classification of Optical Transients with APO 3.5m

ATel #4896; J. L. Prieto (Princeton)
on 19 Mar 2013; 03:07 UT
Credential Certification: Jose L. Prieto (jose@obs.carnegiescience.edu)

Subjects: Optical, Supernovae, Transient

We report spectroscopic observations of three optical transients: SNhunt175 (CRTS discovery), CSS130317:141506+270848 (CRTS discovery), and PSN J16545668+4303077 (Jin & Gao discovery, reported in CBAT TOCP). The spectra (range 350-960nm; res. 0.8nm) were obtained UT Mar. 18 with DIS mounted on the APO 3.5-m telescope. We used SNID (Blondin & Tonry 2007, ApJ, 1024, 666) to aid classification, phase, and redshift determination. SNhunt175 is a normal Type Ia SN around maximum light. After correcting for the recession velocity of its host galaxy (NGC 5910; z=040878 via NED), we measure a Si II (635.5nm) velocity of -11500 km/s. CSS130317:141506+270848 is a Type IIn SN with strong H-alpha and H-beta lines at redshift z=0.125, most similar to SN 1998S and SN 1997cy at late times. Its current magnitude (and redshift) imply a luminous event with MV ~ -20 mag. PSN J16545668+4303077 has the spectrum of a Type II SN a couple of weeks after explosion, showing strong and broad Balmer P-Cygni features and Fe II lines.