The Type IIn 2021gpw in the errorbox of IceCube-20211216B
ATel #15123; Irene Salmaso (Padova Univesity, INAF-OAPd), Enrico Cappellaro (INAF-OAPd), Nancy Elias-Rosa (INAF-OAPd), Achille Fiore (INAF-OAPd), Andrea Reguitti (UAB Chile, INAF-OAPd), Leonardo Tartaglia (INAF-OAPd)
on 17 Dec 2021; 16:42 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Enrico Cappellaro (enrico.cappellaro@oapd.inaf.it)
Subjects: A Comment, Supernovae, Transient
Following the alert of the Ice-Cube collaboration of a (bronze) track-like event Ice-Cube 20211216B (GCN 31249, https://gcn.gsfc.nasa.gov/gcn3/31249.gcn3), we searched the SN archives for interacting SNe within the neutrino errorbox. According to Fang et al. 2020, ApJ, 904, 4, diffusive shock acceleration in interacting SNe is one of the possible sources of high-energy neutrinos up to several months after the SN explosion.
We report the presence of the Type IIn SN 2021gpw (Transient Name Server, https://www.wis-tns.org/object/2021gpw) about 1.17 degrees from the reported position and hence within the 90% PSF containment.
SN 2021gpw was discovered on March 20th, 2021 by ATLAS (Transient Name Server, https://www.wis-tns.org/object/2021gpw/discovery-cert) at a distance of 320 Mpc. Based on the LT spectrum reported in TSN, the SN was classified as Type IIn. The bright, slow-evolving light curve (observed by ZTF, retrieved from the Lasair broker https://lasair.roe.ac.uk/object/ZTF21aaqhqke), reached a peak magnitude of -19.90 +/- 0.06 in the r band on April 25th, 2021. The target was of magnitude r=19.79 +/- 0.20 (absolute magnitude -17.75) at the last ZTF observation (December 2nd, 2021).
We planned for follow-up optical observations in the next few days.
