Spectroscopic Classification of Astrophysical Transients with Keck II + KCWI

ATel #17991; J. Karcheski, R. J. Foley, K. C. Patra (UCSC)
on 19 Aug 2026; 20:53 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Kishore Patra (kcpatra@ucsc.edu)

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We report the classification of AT2026tiz and AT2026wza from spectroscopic observations with the Keck Cosmic Web Imager (KCWI) on the Keck II telescope obtained on 2026 August 14 UT. The targets were supplied by ATLAS and YSE and identified using the target management platform YSE-PZ (Coulter et al., 2023, PASP, 135, 4501). The classifications were performed with SNID-SAGE (Toppa & Smartt, 2026, MNRAS, 549, 4).

 
Name         | IAU Name   | RA (J2000)   | Dec (J2000)  |   z    | Type |  Phase  | Notes
 
PS26fcq      | AT2026tiz  | 22:55:57.161 | +20:21:27.81 | 0.057  |  Ia  |  +25d   | 
ATLAS26jkw   | AT2026wza  | 18:58:07.375 | +48:04:02.28 | 0.020  |  Ib  |  peak   | (1) 
 

Notes: When the redshift is given to 2 decimal places, it is derived from the SN spectrum. Otherwise, the redshift is determined from the host galaxy. (1) The best SNID-SAGE matches are to SN Ia and Ib templates near peak brightness at z ~ 0.02. Assuming that redshift and no host-galaxy extinction, the current absolute magnitude (M_clear = -16.3 mag and not rising quickly; Kono et al. 2026, TNS AT Report 320187) is more consistent with that of a SN Ib than a SN Ia.