TITLE: GCN CIRCULAR NUMBER: 42724 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman DATE: 25/11/17 16:41:19 GMT FROM: André Santos at Centro Brasileiro de Pesquisas Físicas (CBPF) <andsouzasanttos@gmail.com> A. Santos (CBPF), C. D. Kilpatrick (Northwestern), C. R. Bom (CBPF), L. Santana-Silva (CBPF), P. Darc (CBPF), Gabriel Teixeira (CBPF), C. Mendes de Oliveira (IAG-USP) report on behalf of the STEP-GW collaboration Following the subsolar-mass gravitational-wave candidate S251112cm (GCN 42650, 42690), we conducted optical spectroscopic follow-up of four transients: 2025adiw, 2025adim, 2025adhf, and 2025adjf using the Goodman High-Throughput Spectrograph on the SOAR 4.1 m telescope at Cerro Pachón, Chile. Observations were performed on UT 2025 Nov 17 with the 400 l/mm M1 grating, 2×2 binning. For each source we obtained two 900 s exposures and coadded them for analysis. Each target was submitted for spectrum acquisition using the AEON queue. We classified 2025adim, 2025adiw, and 2025adhf as Type Ia supernovae based on SNID-SAGE spectral matches and identifiable SN Ia features. For 2025adjf, the spectra were heavily contaminated by host-galaxy light, preventing a definitive classification, and we instead report the host galaxy redshift based on nebular emission lines in the extracted spectrum. Our classification and redshift estimates are listed as follows: | AT Name | Classification | redshift | |----------|----------------|----------| | [2025adim](https://www.wis-tns.org/object/2025adim) | SN Ia | 0.091 | | [2025adiw](https://www.wis-tns.org/object/2025adiw) | SN Ia | 0.165 | | [2025adhf](https://www.wis-tns.org/object/2025adhf) | SN Ia | 0.098 | | [2025adjf](https://www.wis-tns.org/object/2025adjf) | - | 0.124 | All classified events are best matched to templates of normal or 91T-like SNe Ia at redshifts inconsistent with the expected distance for S251112cm, and thus are unlikely to be associated with the GW candidate. These results are based on observations obtained through the Astronomical Event Observatory Network (AEON), a joint endeavor of Las Cumbres Observatory and NSF NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the U.S. National Science Foundation. View this GCN Circular online at https://gcn.nasa.gov/circulars/42724. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...