TITLE:   GCN CIRCULAR
NUMBER:  43197
SUBJECT: GRB 251222A: PRIME near-infrared detection
DATE:    25/12/23 01:48:17 GMT
FROM:    Joe Durbak at UMD <gcn.joedurbak@gmail.com>

J. Durbak (UMD), N. Passaleva  (U Rome),  O. Guiffreda (UMD), M. El Kabir (U Rome), E. Troja (U Rome), A. S. Kutyrev (NASA/GSFC), S. B. Cenko (NASA/GSFC)

Following the Fermi GBM detection (GCN 43186) and SVOM (Yang et al., GCN 43188), we observed the transient field in Y, J and H filters with PRIME ~2 hours after Fermi and SVOM detections.

At the position of the optical counterpart reported by SVOM/VT (Palmerio et al., GCN 43189), we detect an uncatalogued source in J band. Using nearby VISTA Hemispherical Survey (VHS) stars for preliminary calibration we derive the following magnitudes, not corrected for Galactic extinction:  

Filter | Mag(AB)        |
-------|----------------|
J      | 18.04 +/- 0.02 |         

Further observations are planned.

PRIME is a 1.8m telescope with 1.56 square degree FOV (0.5 arcsec/pixel) located in Sutherland, South Africa at the South African Astronomical Observatory (SAAO) (Kutyrev et al. 2023, Yama et al. 2023, Durbak et al. 2024, Sumi et al. 2025).

We thank the Osaka University observers at PRIME and the staff at SAAO for their support with these observations.