Spectroscopic Classification of Astrophysical Transients with the Lick Shane Telescope

ATel #17309; K. W. Davis, R. J. Foley (UCSC), K. de Soto (CfA), A. Gagliano (IAIFI), L. Izzo (INAF), W. V. Jacobson-Galan (Caltech), G. Narayan (UIUC), V. A. Villar (CfA)
on 25 Jul 2025; 22:09 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Ryan Foley (foley@ucsc.edu)

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We report the classification of AT2025oom and AT2025rxq from spectroscopic observations with the Kast spectrograph on the Shane telescope obtained on 2025 July 25 UT. The targets were supplied by ALeRCE (selected from the ZTF data stream) and YSE. AT2025oom was initially flagged on 2025 July 5 by the LAISS anomaly detection filter (Aleo et al. 2024; Reynolds et al. 2025; https://github.com/VTDA-Group/re-laiss) deployed in the ANTARES alert broker (Narayan et al. 2018; Matheson et al. 2020; https://antares.noirlab.edu/), and was prioritized for follow-up on 2025 July 7 after visual vetting. It was also identified using AA2RTO (Sedgewick et al., 2025), which is fed alerts from Lasair (Smith et al., 2019). Observations were vetted and coordinated using the target management platform YSE-PZ (Coulter et al., 2023). The classifications were performed with SNID (Blondin & Tonry, 2007).

 
Name         | IAU Name   | RA (J2000)   | Dec (J2000)  |   z      |  Type   |  Phase  | Notes
 
ZTF25aawkwoy | SN2025oom  | 18:36:31.215 | +43:38:53.88 | 0.0266   |  SN IIn |         | (1) 
PS25fgp      | SN2025rxq  | 14:26:31.059 | +05:58:23.48 | 0.025621 |  SN II  | pre-max | (2) 
 
 

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 find a blue continuum superimposed with Hydrogen emission lines. Each line profile shows a narrow emission component (FWHM = 670 km/s) atop an intermediate-width P-Cygni line with an absorption velocity of -4000 km/s. (2) The spectrum shows a blue and mostly featureless continuum. We identify a weak H-alpha P-Cygni line at the same redshift as the presumed host galaxy (UGC 9246).