TITLE:   GCN CIRCULAR
NUMBER:  36210
SUBJECT: EP240420a: TNT upper limit to its optical counterpart
DATE:    24/04/21 14:20:00 GMT
FROM:    Wenxiong Li <liwenxiong1992@gmail.com>

J. Mo, X. F. Wang, H. W. Peng (THU), X. Li (BJP), Y. G. Sun, W. X. Li (NAOC) report the optical follow-up observations of EP240420a (Zhang et al., GCN 36194, Han et al., GCN 36203). These observations were conducted on 2024 April 20.75 UT in g and r bands, at ~4 hours after the EP-WXT detection, using the 80-cm Tsinghua-NAOC Telescope (TNT) located at Xinglong Observatory, Hebei Province, China. No optical counterpart candidates were detected.
The 3-sigma upper limits are reported as below:
g ~ 21.6 mag
r ~ 21.9 mag
Further followup observations are encouraged.