GCN Circular 37287
Subject
GRB 240825A: LCO optical observations
Date
2024-08-25T22:27:56Z (a month ago)
From
luca.izzo@inaf.it
Via
Web form
L. Izzo (INAF-OACn and DARK/NBI) and D. B. Malesani (DAWN/NBI and Radboud Univ.) report:
We observed the field of GRB 240825A (Gupta et al., GCN #37274) with the Sinistro instrument mounted on the 1-m telescope of the LCO network, located in Sutherland, South Africa. Observations started on 2024 August 25 at 20:43:23 UT (4.85 hr after the GRB trigger). We obtained a series of 3x120 s images in the SDSS-r filter and 5x120s images in the PS1-z filter.
The optical afterglow counterpart is clearly detected at a location consistent with the source reported by the Swift-UVOT (Gupta et al., GCN #37274) and by other optical observations (Jiang et al., GCN #37275; Dutton et al., GCN #37276; Odeh et al., GCN #37277, Li et al., GCN #37280).
We measure preliminary magnitudes of r = 20.1 +/- 0.1 mag (AB), and z = 19.3 +/- 0.1 mag (AB), calibrated against nearby stars from the Pan-STARRS catalog.
We also notice the presence of an archival source, with an offset of <1" from the GRB optical afterglow, with magnitude r = 22.7 mag (AB) in the Pan-STARRS DR1 catalog. This is a potential host galaxy of GRB 240825A, and is clearly reported in the Legacy Survey DR10 images as well.
This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 101004719.