GCN Circular 45986
Subject
GRB 261017A: R-band upper limit with the 1.3-m DFOT
Event
Date
2026-10-19T07:20:14Z (14 hours ago)
From
pawarpankaj1492@gmail.com
Via
Web form
Pankaj Pawar, Sarvesh Yadav, Dhruv Jain, Anshika Gupta, Debalina Kar and
Kuntal Misra (ARIES, Nainital, India) report:
We observed the field of GRB 261017A (Siegel et al., GCN 45974) with the
1.3-m Devasthal Fast Optical Telescope (DFOT), India, on 2026 October 17.
Observations started at 22:57:29 UT, approximately 6.87 hours after the
Swift trigger. We obtained six 300-s exposures in the R filter.
We do not detect an optical source at the enhanced Swift-XRT position
(Beardmore et al., GCN 45977) in the stacked image. Our preliminary forced
PSF photometry yields the following nominal 5-sigma upper limit:
Mid-time (UT) Tmid-T0 (d) Filter Exposure (s) Mag (Vega)
2026-10-17 23:12:41 0.29695 R 6 x 300 >22.5
T0 is 2026-10-17 16:05:05 UT (Siegel et al., GCN 45974). The mid-time is
the exposure-weighted mean of the individual exposure mid-times.
Photometry was calibrated against 45 nearby Pan-STARRS stars transformed
to approximate Cousins R magnitudes on the Vega system. The limit is based
on the local background noise, including uncertainty in the local sky
estimate, and is not corrected for Galactic extinction.