DRAFT
2026-05-23 14:09:19
Type: Object/s-Discovery/Classification
Bibcode: 2026TNSAN.150....1I
Classification of SN 2026naq as a Type IIb supernova
Authors: L. Izzo (INAF/OACN and DARK/NBI), G. Leloudas (DTU Space), D. B. Malesani (DAWN/NBI and Radboud), K. Valeckas (NOT), on behalf the ENGRAVE collaboration
Source Group: ENGRAVE
Abstract:
We report the classification of SN 2026naq as a Type IIb supernova following a fast-evolving shock-cooling phase.

We used the Nordic Optical Telescope (NOT), equipped with ALFOSC, to observe SN 2026naq, which had been identified as a rapidly fading transient at 100 Mpc by Srivastav et al. 2026 (AN 2026-149).

Observations started on 2026-05-22 at 21:31 UT and consisted of 2 x 1800 sec exposures with grism #4 and a 1.0 arcsec slit (wavelength coverage 3200 - 9600 Å, nominal resolution R = 360). We produced a prompt reduction of the data based on archival calibrations. 

Template comparison with SNID-SAGE (Stoppa & Smartt 2026, arXiv:2603.28741) reveals that SN 2026naq is a Type II SN, with Type IIb being the preferred subtype. This classification is consistent with an early shock-cooling phase, seen in many Type IIb supernovae. 

SNe IIb are a common contaminant in searches for kilonovae (Ackley et al. 2026, arXiv:2605.02639; the ENGRAVE collaboration). 

 

Show current TNS values
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 2026naq 12:51:56.470 +16:16:53.47 SN IIb 0.021 12:51:56.463 +16:16:53.32 SN IIb 0.021

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