Spectroscopic classification of AT2018dfg as a likely IIn SN
ATel #11839; Jennifer Andrews, Nathan Smith (University of Arizona)
on 11 Jul 2018; 08:11 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jennifer Andrews (jandrews@as.arizona.edu)
Subjects: Optical, Supernovae, Transient
The AZTEC (Arizona Transient Exploration and Characterization) collaboration reports an optical spectrum of AT2018dfg obtained on UT 2018 Jul 11.12 (JD 2458310.61) with the Magellan Clay telescope (+ LDSS3 spectrograph, VPH-all grism). The spectrum reveals an unresolved narrow H-alpha emission line with a velocity of 475 km/s, and an intermediate H-alpha emission line with a velocity of ~2000 km/s. A similar profile is seen in H-beta. There are also strong Na ID absorption lines associated with the host galaxy, suggesting high local extinction. The narrow and intermediate emission lines, considerable extinction, and redshift of NGC 5468 (0.00948 from NED) indicates that AT2018dfg is likely a IIn SNe, although other types of CSM interacting SNe cannot be ruled out. Cross-correlation using GELATO (Harutyunyan et al., 2008, A&A, 488, 383) finds a good match with the IIn SN 1998S 3.5 days post explosion.
