TITLE:   GCN CIRCULAR
NUMBER:  40217
SUBJECT: SVOM/sb25042207: XRT observations
DATE:    25/04/23 13:45:35 GMT
FROM:    Antonino D'Ai' at IASF-PA <antonino.dai@inaf.it>

Antonino D'Aì (INAF/IASFPA), J. A. Kennea (PSU), Elena Ambrosi (INAF/IASFPA), Valerio D'Elia (SSDC & INAF-OAR), Andrea Melandri (INAF-OAR) reports on behalf of the Swift-XRT team:

We have analysed 1.8 ks of XRT data for the SVOM/ECLAIRs-detected X-ray transient sb25042207 
(Liang et al., GCN Circ. 40213), from T0+3.8 ks to T0+5.6 ks after the SVOM/ECLAIRs trigger. 
The data are entirely in Photon Counting (PC) mode.

We detect two previously known X-ray sources and two uncatalogued X-ray sources within the ECLAIRs error circle. We note that the ECLAIRs error region overlaps with the Coma cluster region, a well-known galaxy cluster that exhibits significant diffuse X-ray emission.

Details of the uncatalogued sources:

Source 2:
RA (J2000): 194.93972 = 12:59:45.53
Dec (J2000): +27.8781 = +27:52:41.0
Error: 6.0 arcsec (radius, 90% confidence)
Count rate: 8 (+5, -4) x 10^-3 ct/s
Flux: [3.5 (+2.1, -1.9)] x 10^-13 erg/cm^2/s (observed, 0.3–10 keV)

Source 4:
RA (J2000): 195.13942 = 13:00:33.46
Dec (J2000): +27.7478 = +27:44:52.0
Error: 7.5 arcsec (radius, 90% confidence)
Count rate: 0.011 (+0.005, -0.004) ct/s
Flux: [4.8 (+2.1, -1.8)] x 10^-13 erg/cm^2/s (observed, 0.3–10 keV)

Both sources are below the RASS limit and show no definitive signs of fading.

The results of the XRT team's automatic analysis of the tiled XRT observations, 
including a position-specific upper limit calculator, are available at:
https://www.swift.ac.uk/SVOM/SVOM_FIELD00013/

This circular is an official product of the Swift-XRT team.