TITLE: GCN CIRCULAR NUMBER: 36971 SUBJECT: GRB 240727A: observations of optical counterpart. DATE: 24/07/29 12:25:36 GMT FROM: divulgazione@marsec.org Stefano Lora (MarSEC, Marana Space Explorer Center, Marana Di Crespadoro, VI, Italy) Member of: UAI/SSV - Unione Astrofili Italiani/Sezione Stelle Variabili, GRB section. AAVSO (American Association Variable Stars Observers) In collaboration with: Ivo Peretto and Giovanni Furlato (MarSEC, Marana Space Explorer Center, Marana di Crespadoro, VI, Italy) Members of: UAI/SSV - Unione Astrofili Italiani/Sezione Stelle Variabili, GRB section. AAVSO (American Association Variable Stars Observers) report: We imaged the field of GRB 240727A detected by SWIFT(trigger=1245074) with the telescope 14” RC Officina Stellare of MarSEC (Marana Space Explorer Center). The observations with a series of 120 sec exposures started at 2024-07-27 19:40 UT, 952 min. after the GRB trigger, with a Ritchey-Chretien telescope D=360 mm f/ 8. at the following position: RA(J2000) = 15h 45m 44,98s Dec(J2000) = +08d 37' 12,0", Weather conditions were very good without Moon. We co-added 73 exposures of 120 sec each. Start T0+ End T0+ R lim. 952 min 1098 min 17,5 We did not found any optical counterpart in A.R. 15 45 44.98, DEC. +08 37 12.0 position and in the error box of the Swuift candidate. ref.: GCN Circular 36938 Magnitudes were estimated with the APASS and are not corrected for galactic dust extinction. Reference: https://www.marsec.org/ View this GCN Circular online at https://gcn.nasa.gov/circulars/36971. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...