TITLE: GCN CIRCULAR NUMBER: 40620 SUBJECT: GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization DATE: 25/06/03 15:06:50 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma rosa.becerra@roma2.infn.it
Rosa L. Becerra (U Roma), Sahil Atri (U Roma), Alan M. Watson (UNAM), 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), Margarita Pereyra (UNAM) and Eleonora Troja (U Roma) report:
We continued our follow-up campaign of GRB 250602A, detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 40602) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir (http://ddoti.astroscu.unam.mx) on the night of 2025-06-03 UTC.
DDOTI observed the Fermi/LAT error region (Holzmann Airasca et al., GCN Circ. 40611), from 03:51 UTC to 05:01 UTC (from T+24.7 h to T+ 25.9 h after the trigger), obtaining a total exposure time of 48 minutes.
By comparing our observations with the USNO-B1 and Pan-STARRS PS1 DR2 catalogs, and performing image subtraction using a Pan-STARRS PS1 DR2 template, we detect no uncatalogued sources within the observed field down to a 10-sigma limiting AB magnitude of: w > 20.0
Unfortunately, the Fermi/LAT error region was not included in the field observed on the night of 2025-06-02 UTC (Atri et al., GCN Circ. 40610).
This value is not corrected for the Galactic extinction.
We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir.
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