TITLE: GCN CIRCULAR NUMBER: 35956 SUBJECT: X-ray transient EP240315a: PRIME near infrared detection DATE: 24/03/18 18:35:29 GMT FROM: Joe Durbak at UMD <gcn.joedurbak@gmail.com> O. Guiffreda (UMD), J. Durbak (UMD), A. S. Kutyrev (NASA/GSFC), E. Troja (U Rome), K. De (MIT), S. B. Cenko (NASA/GSFC) Following the Einstein Probe detection (GCN 35931) of EP240315a, we observed the transient field in the J filter with PRIME ~1 day after the Einstein Probe detection. At the position of the optical transient AT2024eju reported by ATLAS (Srivastav et al. GCN 35932), we detect an uncatalogued source in J band. Using nearby VISTA Hemispherical Survey (VHS) stars for preliminary calibration we derive the following magnitude, not corrected for Galactic extinction: Filter | Mag(VISTA) | SNR | Seeing | Total exposure time (s) | UT Date-time at start -------|----------------|-----|--------|------------------------------------------------ J | 19.7 +/- 0.3 | 6.0 | 1.3” | 675 | 2024-03-16T19:14:20 This result is consistent with GROND detection (Rau GCN 35937). Conditions were intermittently cloudy, resulting in higher than usual photometric error. PRIME is a 1.8m telescope with 1.56 square degree FOV (0.5 arcsec/pixel) located in Sutherland, South Africa. Further observations are planned. We thank the Osaka University observers at PRIME and the staff at SAAO for their support with these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/35956. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...