TITLE:   GCN CIRCULAR
NUMBER:  37153
SUBJECT: EP240807a: PRIME H-band upper limits
DATE:    24/08/12 17:51:34 GMT
FROM:    O. Guiffreda at UMD <oriogui@umd.edu>

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

Following the Einstein Probe detection (GCN 37088), we observed the transient field in the H filter with PRIME ~22 hours after the EP/WXT detection. This observation was taken directly after the J-band observations reported in GCN 37118.  The total exposure time of the observation was 600s.  

At the position of the fast x-ray transient, we detect no uncatalogued source in H band. Using nearby 2MASS stars for preliminary calibration we derive the following limiting magnitudes, not corrected for Galactic extinction:  

Filter | Mag(AB)        | Total exposure time (s) 
-------|----------------|-------------------------
H      | >21.1 +/- 0.1  | 600

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).

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