Spectroscopic Classification of Astrophysical Transients with KCWI on the Keck II Telescope

ATel #18110; R. Kaur, R. J. Foley (UCSC), T. Murphey (UIUC)
on 19 Oct 2026; 00:46 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Ravjit Kaur (ravkaur@ucsc.edu)

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We report the classifications of astrophysical transients from spectroscopic observations with the Keck Cosmic Web Imager (KCWI) on the Keck II telescope obtained on 2026 October 15 UT. The targets were supplied by YSE, ZTF, ALeRCE, and PSST. Targets were identified using the target management platform YSE-PZ (Coulter et al., 2023, PASP, 135, 4501). The classifications were performed with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024) and SNID-SAGE (Toppa & Smartt, 2026, MNRAS, 549, 4).

 
Name             | IAU Name    | RA (J2000)   | Dec (J2000)  |    z    |   Type    | Phase | Notes
 
PS26hnx          | AT2026abft  | 03:33:35.898 | -27:45:51.94 |  0.221  |   SN Ia   | +20 d |  
PS26itx          | AT2026adic  | 03:34:44.323 | -04:23:54.37 |  0.0354 |   SN Ic   | +10 d |  
ZTF26acaedmf     | AT2026aert  | 10:30:53.193 | +51:19:52.35 |  0.0461 |   SN Ib   | +5 d  | (1) 
PS26jna          | AT2026aeow  | 02:18:57.851 | -15:13:38.52 |  0.0529 |   SN Ia   | -3 d  | (2) 
ZTF26acaznbf     | AT2026aexm  | 10:52:30.883 | +07:13:17.56 |  0.0205 |   SN Ia   | +30 d |  
PS26joo          | AT2026afmu  | 05:53:03.666 | +53:15:36.71 |  0.11   | SN Ia-91T | -10 d | 
                 | AT2026afma  | 03:28:21.318 | -27:22:51.55 |  0.147  |   SN Ia   | peak  | (3) 
                 | AT2026afmi  | 03:35:52.701 | -28:02:49.10 |  0.16   |   SN II   | +10 d |  
                 | AT2026afmv  | 03:33:28.139 | -29:20:14.76 |         |           |       | (4) 
 

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) We measure a He I 7065 absorption velocity of -12,200 km/s. (2) We measure a Si II 6355 absorption velocity of -12,000 km/s. (3) We measure a Si II 6355 absorption velocity of -11,000 km/s. (4) The spectrum is blue and relatively featureless. There is a single absorption feature at 4200 A, which has a weak redshifted emission component, consistent with a P-Cygni profile. If this is a broad, blueshifted Ca H&K feature, the redshift is ~0.13.