AT 2021tf was classified as a QSO at redshift z = 1.54 (2021TNSCR.120....1T). Their initial spectrum shows He II 4686 and N III/C III flash features. Additionally, the presence of the nearby galaxy SDSS J235603.81+534334.7 at photometric z = 0.059 ± 0.023 led us to suspect that the QSO classification may be incorrect.
Indeed, a spectrum obtained on MJD 59235.17 (~13 days post discovery) using the 3-m Shane telescope at Lick Observatory shows that QSO is the incorrect interpretation. We report that AT 2021tf is instead a Type Ibn supernova at z = 0.041. We identify narrow P-Cygni features associated with He I at 5876, 6678, 7065, and 7281 Angstroms, and C II features at 6578 and 7236 Angstroms, at z = 0.041. A SNID analysis (Blondin & Tonry 2007, 2007ApJ...666.1024B) shows a match to SN 2006jc, a SN Ibn in a dense He rich-circumstellar medium.
ZTF is a project led by PI S. R. Kulkarni at Caltech, and includes IPAC; WIS, Israel; OKC, Sweden; JSI/UMd, USA; UW,USA; DESY, Germany; NRC, Taiwan; UW Milwaukee, USA and LANL USA. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. Alert distribution service provided by the DiRAC Institute at the University of Washington. Alert filtering is being undertaken by the GROWTH marshal system, supported by NSF PIRE grant 1545949. W. M. Keck Observatory access was supported by Northwestern University and the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).
Catalog | Name | Reported RA | Reported DEC | Reported Obj-Type | Reported Redshift | Host Name | Host Redshift | Remarks | TNS RA | TNS DEC | TNS Obj-Type | TNS Redshift |
---|---|---|---|---|---|---|---|---|---|---|---|---|
TNS | 2021tf | 23:56:05.110 | +53:43:46.60 | SN Ibn | 0.041 | 23:56:05.110 | +53:43:46.60 | SN Ibn | 0.041 | |||
TNS | 2006jc | 09:17:20.779 | +41:54:32.69 | SN Ib/c | UGC 4904 | 09:17:20.779 | +41:54:32.69 | SN Ibn | 0.005574 |
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