TITLE: GCN CIRCULAR NUMBER: 40748 SUBJECT: GRB 250615A: DDOTI Optical Upper Limit DATE: 25/06/16 12:02:03 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma rosa.becerra@roma2.infn.it
Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Sahil Atri (U Roma), 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 observed the field of GRB 250615A detected by Swift (Dichiara et al., GCN Circ. 40736) 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 2025-06-16 UTC.
DDOTI observed the enhanced Swift-XRT position (Goad et al., GCN Circ. 40739) from 05:18 UTC to 09:55 UTC (from T+6.9 h to T+ 11.5 h after the trigger), obtaining a total exposure of 1.6 hours, alternating with other scientific programs.
Comparing our observations to Pan-STARRS PS1 DR2 catalogues, we detect no uncatalogued fading sources within the observed field down to a 3-sigma limiting AB magnitude of:
w >19.3
This upper limit is consistent with the non-detection reported by Swift/UVOT (Kuin et al., GCN Circ. 40747).
This value is not corrected for Galactic extinction, which is significant due to the burst’s proximity to the Galactic plane.
We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir.
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