TITLE:   GCN CIRCULAR
NUMBER:  45436
SUBJECT: GRB 260822A: EP/FXT follow-up observations
DATE:    26/08/24 15:20:24 GMT
FROM:    SVOM_group <svomgroup@bao.ac.cn>

D. Turpin, S. Schanne (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud) and J. P. Feng (USTC) report on behalf of the SVOM and Einstein Probe teams:

EP-FXT performed a follow-up observation of GRB 260822A detected by SVOM/ECLAIRs (Schanne et al., GCN 45422). The observation started at 2026-08-23T12:00:29.920 (UTC), about 19.2 hr after the SVOM trigger, with a total exposure time of around 5.8 ks.

On-ground analysis of the FXT data found several uncataloged sources inside the ECLAIRs error region. 

Detected both in FXT A and B:
=============================================================
Name | RA | DEC | dist from ECL position | Flux  [0.5-10keV]
     |    |     |      (arcmin)          | (erg/cm^2/s)          
=============================================================
EPF_J000959.8+012409 | 2.4997 | 1.4010 | 4.6072 | 1.2304e-13
EPF_J000926.2+012804 | 2.3576 | 1.4675 | 6.2141 | 7.2405e-14 

Detected in FXT A only:
=============================================================
Name | RA | DEC | dist from ECL position | Flux  [0.5-10keV]
     |    |     |      (arcmin)          | (erg/cm^2/s)          
=============================================================
EPF_J001001.7+011925 | 2.5071 | 1.3237 | 6.3032 |  5.673e-14
EPF_J000930.4+012950 | 2.3758 | 1.4964 | 7.1176 | 6.5814e-14
EPF_J001016.0+012360 | 2.5668 | 1.3999 | 8.5952 |  5.3425e-14

Detected in FXT B only:
=============================================================
Name | RA | DEC | dist from ECL position | Flux  [0.5-10keV]
     |    |     |      (arcmin)          | (erg/cm^2/s)          
=============================================================
EPF_J000951.2+011738 | 2.4632 | 1.2940 | 6.1105 | 4.1612e-14
EPF_J001002.6+011947 | 2.5108 | 1.3271 | 6.3608 | 4.8955e-14
EPF_J000915.7+012111 | 2.3155 | 1.3529 | 6.8404 | 2.1891e-14
EPF_J000930.4+012948 | 2.3757 | 1.4971 | 7.1584 | 5.1928e-14
EPF_J000947.5+013106 | 2.4477 | 1.5183 | 7.9462 | 2.6114e-14
EPF_J000928.0+013037 | 2.3667 | 1.5103 | 8.1030 | 4.2864e-14

with uncertainties of 10 arcsec (radius, 90% C.L. statistical and systematic). 

At this stage, we can not identify any significant flux variability from these sources. A second EP/FXT ToO has been requested in order to conclude about the association of the EP/FXT sources with GRB 260822A.

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).