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Spectroscopic classification of PSN J02451711+4213503 in an anonymous galaxy and PSN J00291512+0251576 in NGC 128

ATel #6378; D. K. Sahu, G. C. Anupama and S. Srivastav (Indian Institute of Astrophysics, Bangalore, India)
on 9 Aug 2014; 08:53 UT
Credential Certification: G.C. Anupama (gca@iiap.res.in)

Subjects: Optical, Supernovae

We report the classification of PSN J02451711+4213503 in an anonymous galaxy and PSN J00291512+0251576 in NGC 128 based on low resolution spectrum (range 350 - 920 nm) obtained using the 2m Himalayan Chandra Telescope (+HFOSC) at the Indian Astronomical Observatory.

A spectrum of PSN J02451711+4213503 obtained on August 08.92 UT shows a prominent SiII (635.5 nm) feature. The SuperNova IDentification code SNID (Blondin & Tonry 2007, ApJ, 666, 1024) gives a best match with the SN 1991T-like type Ia supernova SN 1997br at about two weeks after maximum, at a redshift of z = 0.030 +/- 0.004. Correcting for this redshift, the expansion velocity measured with the minimum of the SiII line is ~9,300 km/sec.

A spectrum of PSN J00291512+0251576 obtained on August 08.95 UT exhibits a prominent Si II 635.5 nm absorption trough, pronounced SiII 597.2 nm line and TiII absorption at ~430 nm. SNID provides a best match of the observed spectrum with the underluminous type Ia supernova SN 1991bg close to maximum. Adopting a redshift of z = 0.0141 for the host galaxy NGC 128 (de Vaucouleurs et al. 1991, Third Reference Catalogue of Bright Galaxies), the expansion velocity deduced from the Si II 635.5 nm absorption feature is ~8,900 km/sec.