AstroNote 2025-304

We report the classification of four optical transients observed on 2025 October 20. Observations were performed on the Nordic Optical Telescope (NOT) at El Roque de Los Muchachos (La Palma, Spain) using the ALFOSC instrument as part of the 2025 NOT observing school at the University of Turku.

Classifications were done using SNID (Blondin & Tonry 2007 2007ApJ...666.1024B). AT 2025aafh is reproduced well by a SN Ia spectrum (normal or 91T-type) slightly before peak brightness. AT 2025aaoz and AT 2025aard are matched by a normal SN Ia around peak. Meanwhile, AT 2025aaxf matches an AGN spectrum, and its coordinates correspond to the ZTF target ZTF19aagzanb with a long variable light curve. SN 2025zwn was previously reported to be a SN II (TNS Classification Report No. 22254) at z=0.04, while we obtain a good match to SN 1993J, a SN IIb, at a redshift of roughly z=0.035 and slightly before peak.

The redshifts of AT 2025aadr and SN 2025zwn are based on the SNID fits, as no host galaxy lines are clear in the spectra. For AT 2025aaoz, an SDSS spectrum of its host galaxy (J074819.11+175622.2) returns a redshift consistent with the SNID fit. The redshift of AT 2025aaxf is based on narrow lines of H I and O III in the spectrum. Finally, the redshift of AT 2025aafh was obtained from the NASA/IPAC Extragalactic Database (host galaxy CGCG 438-028).