TITLE:   GCN CIRCULAR
NUMBER:  36064
SUBJECT: GRB 240411B: LCO optical afterglow detection
DATE:    24/04/11 18:43:10 GMT
FROM:    luca.izzo@inaf.it

L. Izzo (INAF-OACn & DARK/NBI), D. B. Malesani (DAWN/NBI and Radboud Univ.), M. Della Valle and R. Martone (INAF-OACn) report:

We observed the field of GRB 240411B (Parsotan et al., GCN 36063) with the Sinistro instrument mounted on the 1-m telescope of the LCO network, located at Siding Spring Observatory, Australia. Observations started on April 11 at 17:02:54 UT (1.5 hours after the GRB trigger). We obtained a series of 3x180 s images in the r filter.

In the stacked image, we detect a new source within the XRT position, at the coordinates:

RA(J2000) = 15:26:10.17
Dec(J2000) = -02:08:46.8

We measure a preliminary magnitude of r = 21.66 +- 0.22 (AB), calibrated against nearby stars from the Pan-STARRS catalog.

This source is not visible in the Pan-STARRS catalog and is thus very likely the optical afterglow of GRB 240411B.

This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 730890.