GCN Circular 37700

J. Durbak (UMD), O. Guiffreda (UMD), S. Atri (U Rome), A. S. Kutyrev (NASA/GSFC), E. Troja (U Rome), K. De (MIT), S. B. Cenko (NASA/GSFC)

Following the Fermi GBM detection (GCN 37668

), we observed the transient field in J and H filters with PRIME ~16 hours after FERMI detection.

At the position of the optical counterpart reported by GOTO (GCN 37676

), we detect an uncatalogued source in J and H bands. Using nearby VISTA Hemispherical Survey (VHS) and 2MASS stars for preliminary calibration we derive the following magnitudes, not corrected for Galactic extinction:

Filter	Mag(AB)
J	20.0 +/- 0.2
H	19.6 +/- 0.1

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).

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