TITLE: GCN CIRCULAR NUMBER: 40013 SUBJECT: GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit DATE: 25/04/02 20:48:13 GMT FROM: Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, Messina, Italy giovannicalapai@tiscali.it
Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, (Messina) Italy Member of: GRB/UAI Gamma Ray Burst Section of Unione Astrofili Italiani.
Report:
We imaged the field of GRB 250331C detected by Swift Burst Alert Telescope (BAT) (Cenko et al. GCN 39959), with the 11 inches Schmidt-Cassegrain (Celestron 11) telescope F/D=6,3.
The observations were started at 2025-03-31 20:59 UT (approximately 16.37 hours after burst) stacking a set of unfiltered CCD image. The observations were made with modest sky conditions and the target low on the horizon.
We co-added 30 exposures of 60 sec each.
Start T0+ End T0+ CR lim 16.37 hour 16.92 hour 18.7
We did not found any optical counterpart in the error box of the XRTcandidate. Evans GCN 39960
Magnitudes were estimated with the PanSTARRS cat. and are not corrected for galactic dust extinction.
Our observations are consistent with other already reported Dornic et al. (GCN 39963), Lipunov et al. (GCN 39981), Siegel et al. (GCN 40003).
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