TITLE: GCN CIRCULAR NUMBER: 41198 SUBJECT: GRB 250725A: PRIME near-infrared observations DATE: 25/07/29 20:55:52 GMT FROM: Joe Durbak at UMD gcn.joedurbak@gmail.com
J. Durbak (UMD), O. Guiffreda (UMD), N. Passaleva, M. El Kabir, A. S. Kutyrev (NASA/GSFC), E. Troja (U Rome), S. B. Cenko (NASA/GSFC)
Following the Fermi GBM (GCN 41150) and Swift BAT (GCN 41152), we observed the transient field in J and H filters with PRIME ~24 hours after Fermi and Swift detection.
At the position of the optical counterpart reported by MASTER-Net (GCN 41151), we detect a low-significance uncatalogued source in H-band. Using nearby VISTA Hemispherical Survey (VHS) and 2MASS stars for preliminary calibration we derive the following magnitude and limit, not corrected for Galactic extinction:
| Filter | Mag(AB) | Calibration Survey | |--------|--------------|--------------------| | J | > 20.6 | VHS | | H | 20.6 +/- 0.3 | 2MASS |
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.
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