TITLE:   GCN CIRCULAR
NUMBER:  38140
SUBJECT: EP241109a: EP on-board trigger and autonomous follow-up observation
DATE:    24/11/09 08:26:08 GMT
FROM:    EP Team at NAOC/CAS <ep_ta@bao.ac.cn>

A.Li (BNU), C.-Y. Wang (THU), H.-Y. Liu (NAO, CAS), Y.-C. Fu (BNU), X.-L. Chen, Kaushik Chatterjee (YNU), and H. W. Pan (NAO,CAS) report on behalf of the Einstein Probe team:

We report on the detection of an X-ray transient detected by EP-WXT, EP241109a, which triggered the on-board processing unit at 2024-11-09T06:01:55Z (UTC) (trigger ID: 01709118383). An autonomous observation on the X-ray transient was performed by the EP-FXT, which detected an X-ray source at R.A. = 18.3599 deg, DEC = 0.0184 deg (J2000) with an uncertainty of about 15 arcsecs (radius, 90% C.L. statistical and systematic), consistent with the position of the WXT transient within the uncertainties.

In the GAIA DR3 database, there is a close star (effective temperature is about 3200 K, distance is about 71.83 pc) within the EP-FXT error circle of EP241109a. Hence, the possibility that EP241109a is a stellar flare event cannot be ruled out. Further follow-up observations are encouraged to explore the orgin of EP241109a.

Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).