Spectroscopic classification of ASASSN-17fe, ASASSN-17fd by NUTS (NOT Un-biased Transient Survey)

ATel #10298; G. Cannizzaro (SRON), Z. Kostrzewa-Rutkowska (SRON), M. Stritzinger (Aarhus University), S. Dong (KIAA-PKU), S. Benetti (INAF-OAPd), M. Fraser (UCD) and R. Tronsgaard Rasmussen (Aarhus University) on behalf of the NUTS collaboration
on 21 Apr 2017; 12:36 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Zuzanna Kostrzewa-Rutkowska (zkostrzewa@astrouw.edu.pl)

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The Nordic Optical Telescope (NOT) Unbiased Transient Survey (NUTS; ATel #8992) reports the spectroscopic classification of ASASSN-17fe and ASASSN-17fd (in an anonymous host galaxy and ARK 481 respectively). The candidates were discovered by the All Sky Automated Survey for SuperNovae (ASAS-SN, ATEL #8944, #8979).

The observations were performed with the 2.56 m Nordic Optical Telescope equipped with ALFOSC (range 350-950 nm; resolution 1.6 nm FWHM).

 
Survey Name    | IAU Name  | Discovery (UT)  | Discovery mag | Observation (UT) | Redshift | Type    | Phase     | Notes  
ASASSN-17fe    | 2017dfo   | 2017-04-19.11   | 17.03         | 2017-04-20.875   | 0.036    | Ia      | -6/-2d    |  (1) 
ASASSN-17fd    | 2017dfb   | 2017-04-19.5    | 16.5          | 2017-04-21.125   | 0.0256   | Ia-91T  | -7/-4d    |  (2) 

(1) ASASSN-17fe is a pre-maximum normal Type Ia supernova. SNID gives good matches with normal SN Ia between -6 and -2 days. An expansion velocity of about 10600 km/s from the SiII 635.5 nm absorption was measured.

(2) ASASSN-17fd is a pre-maximum 1991T-like Type supernova. GELATO gives good fits with SN 1991T spectra between -7 and -4 days. The redshift has been deduced from a strong NaI-D interstellar absorption. With this z, an expansion velocity of about 10800 km/s from the SiII 635.5 nm was measured.

Classifications were performed using the GELATO (Harutyunyan et al. 2008, A&A, 488, 383) and SNID (Blondin and Tonry 2007, ApJ, 666, 1024) tools. Calibrated spectra and additional information can be retrieved in the IAU Transient Name Server.