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FLOYDS Classification of MASTER OT J161308.18+260953.3 as a Type II Supernova and ASASSN-17cq/AT 2017axl as a Type Ia Supernova Near Peak

ATel #10112; G. Hosseinzadeh, I. Arcavi, D. A. Howell, C. McCully (Las Cumbres Obs./UCSB), S. Valenti (UC Davis)
on 22 Feb 2017; 23:29 UT
Credential Certification: Iair Arcavi (iarcavi@lcogt.net)

Subjects: Optical, Supernovae

We obtained a spectrum of MASTER OT J161308.18+260953.3 (ATel #10099) on 2017 February 21.5 UT with the robotic FLOYDS instrument mounted on the Las Cumbres Observatory (LCO) 2-meter telescope on Haleakala, Hawai'i. Using Superfit (Howell et al. 2005, ApJ, 634, 1190), we find a good fit to the Type II SN 2005cs 6 days after maximum light at redshift z=0.03. At this redshift, the unfiltered absolute magnitude at discovery was approximately -17.7 mag, so the supernova is not superluminous, as previously suggested.

We also obtained a spectrum of ASASSN-17cq/AT 2017axl (ATel #10108) on 2017 February 22.6 UT with FLOYDS on the LCO 2-meter in Siding Spring, Australia. From extended H-alpha emission in the 2D spectrum, we derive a redshift of z=0.034 for the host galaxy. At this redshift, the absolute magnitude at discovery was M_V = -19.0 mag. Using Superfit, we find a good fit to the normal Type Ia SN 2002bo 1 day before maximum light. The spectrum of SN 2017axl is available on the Transient Name Server.