TITLE: GCN CIRCULAR NUMBER: 39305 SUBJECT: EP250207B: GTC Near-Infrared Observations DATE: 25/02/12 22:09:01 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma rosa.becerra@roma2.infn.it
Yu-Han Yang (U Rome), Rosa L. Becerra (U Rome), Alan M. Watson (UNAM), Eleonora Troja (U Rome), Simone Dichiara (PSU) and Lei Hu (CMU) report on behalf of a larger team:
We observed the field of EP250207B detected by EP/WXT (Zhou et al., GCN 39266) with the OSIRIS instrument on the GTC telescope starting at 2025-02-12 05:22 UTC (T+4.31 days after the trigger). We obtained a total integration of 480 seconds (8x60 s) in z with a seeing of about 1.2 arcsec.
We performed image subtraction on the stacked images using reference images from the Legacy Survey DR10 (Dey et al. 2019).
In our preliminary analysis, we detect artifacts of the image subtraction at the position of the Liverpool Telescope candidate (Eyles-Ferris et al. GCN 39281). However, we do not detect a significant source at this position.
In both our data and the Legacy Survey images, we do not detect a source at the right ascension and declination given by Fraser et al. (GCN 39287) and consider that perhaps there is a small error in this stated position. However, we do detect two sources close to their reported position. Both are visible in the Legacy Survey DR10 catalog (Dey et al. 2019) with a photo-z~0.9, and we do not detect any evidence of brightening.
Finally, at the position of the NOT candidate reported by Liu et al.,(GCN 39300), we do not detect any source down to a limit of 3-sigma z > 23.8 AB. This value is not corrected for Galactic extinction.
Further observations are planned.
We thank the staff of the GTC, especially Gianluca Lombardi and Antonio Cabrera, for their help and rapid execution of these observations.
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