TITLE: GCN CIRCULAR NUMBER: 39055 SUBJECT: GRB 250127B: DDOTI Upper Limit on the Afterglow DATE: 25/01/28 14:48:39 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma rosa.becerra@roma2.infn.it
Rosa L. Becerra (U Rome), Alan M. Watson (UNAM), Eleonora Troja (U Rome), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), and Margarita Pereyra (UNAM) report:
We observed the field of the GRB 250127B detected by Fermi/GBM (Fermi GBM Team, GCN 39046) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir (http://ddoti.astroscu.unam.mx) on 2025-01-28 from 10:24 to 10:53 UTC (19.2 to 19.7 hrs after the event). Our observations cover about the 70% of the error region (statistical only) down to a 10-sigma limiting magnitude of w = 20 AB mag.
Comparing our observations to the USNO-B1 and PanSTARRS PS1 DR2 catalogues, we detect no uncatalogued sources within the observed field to our 10-sigma limit within the error radius reported by Fermi/GBM (Fermi GBM Team, GCN 39046). This upper limit is consistent with the non detection from the Global MASTER-Net (Lipunov et al., 2025, GCN 39049).
We thank the DDOTI technical team and the staff of the Observatorio Astronómico Nacional.
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