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/