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GCN Circular 41198

Subject
GRB 250725A: PRIME near-infrared observations
Date
2025-07-29T20:55:52Z (19 days ago)
From
Joe Durbak at UMD <gcn.joedurbak@gmail.com>
Via
Web form

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

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) 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

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), 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:

FilterMag(AB)Calibration Survey
J> 20.6VHS
H20.6 +/- 0.32MASS

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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