TITLE:   GCN CIRCULAR
NUMBER:  41335
SUBJECT: GRB 250812A: EP-FXT counterpart detection
DATE:    25/08/13 01:33:04 GMT
FROM:    EP Team at NAOC/CAS <ep_ta@bao.ac.cn>

H. Zhou (PMO, CAS), M.-H. Zhang and W.-D. Zhang (NAO, CAS) on behalf of the Einstein Probe (EP) team:

EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 250812A (SVOM/sb25081201, Xin et al. GCN 41322) at 2025-08-12T04:21:33 (UTC), about 1.6 hour after the SVOM/ECLAIRs trigger, with an exposure time of 3578s. One uncatalogued source is detected within the ECLAIRs error circle, and the source is spatially consistent with the counterpart reported in optical and X-ray bands (He et al. GCN 41324, Sbarrato et al. GCN 41325, Xin et al. GCN 41326, Rakotondrainibe et al. GCN 41328, Freeberg et al. GCN 41331, Evans et al. GCN 41334). Preliminary analysis on this source are automatically conducted, and details are listed as follows. 

Source 1: EPF_J021113.9-430953
RA (J2000): 32.8080
Dec (J2000): -43.1644
Flux: 3.76 x 10^-12 erg/s/cm2 (observed, 0.5-10 kev)
Flux_err: 2.31 x 10^-13 erg/s/cm2 (1 sigma)

The position uncertainty of the source is about 10 arcsec in radius (90% C.L. statistical and systematic).

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).