AT 2021pb is a Young Type IIb Supernova
ATel #14320; D. Milisavljevic, K. E. Weil (Purdue University), J. Rupert (MDM Observatory), G. Dimitriadis, M. Siebert, R. J. Foley (UC Santa Cruz), D. Matthews, W. Jacobson-Galan, R. Margutti (Northwestern University)
on 14 Jan 2021; 00:25 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: D. Milisavljevic (dmilisav@purdue.edu)
Subjects: Optical, Supernovae, Transient
We report photometry and spectroscopy of AT2021pb (ZTF21aabxjqr, ATLAS21agp) confirming that it is a young Type IIb supernova.
The transient was first reported by the Zwicky Transient Facility (ZTF; Bellm+ 2019, PASP, 131), and then identified as a target of interest by the Young Supernova Experiment (YSE; Jones+ 2020, arXiv:2010.09724). Observations obtained January 9.4 and 10.5 UT with the MDM 2.4m Hiltner telescope (+OSMOS) show an overall blue continuum with subtle absorptions consistent with H alpha and He I 5876 with velocity -16,000 km/s when corrected for the redshift of the host galaxy (CGCG 265-032, z=0.033; NED). A subsequent spectrum obtained with the LRIS spectrograph on the Keck I 10m telescope on January 13 show that these absorptions have developed into conspicuous P-Cyg features consistent with a Type IIb supernova. Best matches using SNID are SN 1993J and SN 2003bg one week before maximum light.
ZTF public photometry indicates that the supernova was rapidly declining during the MDM observations, which we interpret as a period of cooling envelope emission. The latest ZTF-r measurement indicates that the supernova is now rebrightening. Follow up observations are encouraged.
Name | IAU Name | RA (J2000) | Dec (J2000) | z | Type | Phase | Notes
ZTF21aabxjqr | AT2021pb | 9:44:46.799 | +51:41:14.67 | 0.033 | IIb | -7 |
