TITLE:   GCN CIRCULAR
NUMBER:  35597
SUBJECT: GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
DATE:    24/01/23 00:32:46 GMT
FROM:    Ben Gompertz at U of Birmingham <b.gompertz@bham.ac.uk>

B. P. Gompertz (U. Birmingham) reports for a larger collaboration:


We observed the position of the GOTO candidate optical counterpart (Kumar et al, GCN 35596) to the MAXI-detected GRB 240122A (Negoro et al, GCN 35593) with the IO:O optical camera on the 2m robotic Liverpool Telescope. Observations consisted of 3x60s exposures in each of the SDSS r, i, and z filters under seeing of 2.1”, beginning at 23:36:51 UT on 2024-01-22, 13.1 hours after the GRB trigger. We do not detect the source to a 3-sigma limiting magnitude of r(AB) > 19.36. This non-detection indicates fading of more than two magnitudes in the ~12.4 hours since the GOTO detection.
Magnitudes were calibrated to PS1 stars and are not corrected for Galactic extinction.