Spectroscopic classification of PTSS-18fdb (AT 2018cni) as a peculiar type Ia supernova before maximum
ATel #11728; Jujia Zhang (YNAO), Hanjie Tan(CCU), Wenxiong Li(THU), Bin Li (PMO),Zhitong Li(THU), Xiaofeng Wang(THU),Zhijian Xu, Haibin Zhao(PMO) and Lifan Wang (PMO/TAMU)
on 18 Jun 2018; 10:27 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Ju-Jia Zhang (jujia@ynao.ac.cn)
Subjects: Optical, Supernovae
We obtained an optical spectrum (range 350-890 nm) of PTSS-18fdb (AT 2018cni), discovered by the PMO-Tsinghua Supernova Survey (PTSS, http://www.cneost.org/ptss/ ), on UT 2018 June 17.7 with the Li-Jiang 2.4 m telescope (LJT+YFOSC) at Li-Jiang Observatory of Yunnan Observatories. The spectrum shows that is a peculiar type Ia supernova at about a few days before the maximum light. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that it matches with SN 2005hk at t = - 3 days. Given a redshift of 0.032 for the host galaxy derived from SNID fitting, an expansion velocity of about 5500 km/s can be deduced from the Si II 635.5 absorption minimum.