Spectroscopic Classification of AT2025agby with Keck II + KCWI
ATel #17554; R. Kaur, K. W. Davis, R. J. Foley (UCSC)
on 22 Dec 2025; 18:22 UT
Credential Certification: Ryan Foley (foley@ucsc.edu)
Subjects: Optical, Supernovae, Transient
We report the classification of AT2025agby from spectroscopic observations with the Keck Cosmic Web Imager (KCWI) on the Keck II telescope obtained on 2025 December 16 UT. The targets was supplied by SNHunt. The target was identified using the target management platform YSE-PZ (Coulter et al., 2023, PASP, 135, 4501). The classification was performed with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).
Internal Name | IAU Name | RA (J2000) | Dec (J2000) | z | Type | Phase | Notes
Not reported | AT2025agby | 02:25:43.241 | +37:14:18.69 | 0.036902 | LBV/SN IIn | | (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 spectrum has several strong, narrow (FWHM ~ 600 km/s) H emission lines. We note that the object is offset from its host galaxy by ~24 kpc in projection, and at an intermediate luminosity between what is typical for SNe IIn and LBV-like outbursts. Follow-up observations are encouraged.
