TITLE: GCN CIRCULAR NUMBER: 33173 SUBJECT: GRB 230116C: Swift detection of a burst DATE: 23/01/16 15:53:25 GMT FROM: David Palmer at LANL E. Sonbas (Adiyaman Univ.), R. A. J. Eyles-Ferris (U Leicester), C. Gronwall (PSU), J.D. Gropp (PSU), A. Y. Lien (U Tampa), K. L. Page (U Leicester), D. M. Palmer (LANL), A. Tohuvavohu (U Toronto) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 15:33:21 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 230116C (trigger=1149250). Due to an observing constraint, Swift could not slew to the burst. The BAT on-board calculated location is RA, Dec 223.463, -16.871 which is RA(J2000) = 14h 53m 51s Dec(J2000) = -16d 52' 16" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). Although this is an image trigger, the BAT lightcurve seems to show a complex structure starting around T-50 until a pre-planned slew away from the burst location at T+30, with a peak of ~300 counts/s (15-350 keV) near the time of the trigger. Due to a Moon observing constraint, Swift cannot slew to the BAT position until 09:10 UT on 2023 January 18. There will thus be no XRT or UVOT data for this trigger before this time. Burst Advocate for this burst is E. Sonbas (edasonbas AT yahoo.com). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)