TITLE:   GCN CIRCULAR
NUMBER:  36211
SUBJECT: EP240417a: no counterpart detection by SOAR
DATE:    24/04/21 16:01:11 GMT
FROM:    JONATHAN QUIROLA VASQUEZ <jaquirola@uc.cl>

J. Quirola-Vásquez (Radboud Univ.), F. E. Bauer (PUC), P.G. Jonker (Radboud Univ.), A. J. Levan (Radboud Univ. & Warwick Univ.), D. B. Malesani (DAWN/NBI and Radboud Univ.) on behalf of a larger collaboration:

We observed the field of the Einstein Probe fast X-ray transient EP240417a (Hu et al., GCN 36161) with the SOAR telescope of Cerro Pachón observatory on 2024-04-20 starting (UT) 00:22:04.167, i.e., ~2.4 days after the X-ray trigger. We took 2 images using the Goodman Spectrograph RedCam in imaging mode, and  the i-SDSS filter, with a total exposure time of 1100 seconds. We did not detect an optical counterpart in the field of EP240417a (R.A. = 177.442 deg and DEC = -15.438 deg, with an uncertainty of 3 arcmin) down to the limiting magnitude of i~23 AB mag. None new detection or >2sigma variability regarding the Legacy catalog. We used the PanSTARRS catalog as the magnitude reference for calibration.

We acknowledge the excellent support from the SOAR staff.