TITLE: GCN CIRCULAR NUMBER: 40528 SUBJECT: EP#01709176612: Swift-XRT counterpart detection of flaring star DATE: 25/05/22 19:17:02 GMT FROM: Phil Evans at U of Leicester <pae9@star.le.ac.uk> P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi (INAF-IASFPA) , A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), D.N. Burrows (PSU), M. Capalbi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), M. Ferro (INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Einstein Probe/WXT-detected source EP#01709176612, collecting 2.0 ks of Photon Counting (PC) mode data between T0+4.2 ks and T0+9.7 ks after the trigger. A candidate counterpart has been found. The details of this source are: Source 1 (SWIFT J122501.5-521613): ================================== RA (J2000.0): 186.2566 = 12h 25m 01.58s Dec (J2000.0): -52.2705 = -52d 16' 13.8" Error: 3.5 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 23 arcsec from the Einstein Probe/WXT position. Mean rate: 2.883 +/- 0.078 ct s^-1 Mean flux: (9.45 +/- 0.26)e-11 erg cm^-2 s^-1 Peak rate: 5.3 +/- 1.1 ct s^-1 Peak flux: (1.74 +/- 0.37)e-10 erg cm^-2 s^-1 ECF: 3.28e-11 erg cm^-2 ct^-1, assuming NH=2.18e+21 cm^-2, gamma=2.19; determined from a spectral fit. This matches a catalogued X-ray source XMMSL3 J122501.2-521616 in the XMM-NEWTON/XMMSLEWCLN catalogue. Details: Separation: 2.9" from the XRT source Cat Rate: 6.3e-01 +/- 2.6e-01 ct s^-1 Cat Flux: 5.5e-12 +/- 2.3e-12 erg cm^-2 s^-1 (0.3-10 keV) so the source is 4.5-sigma above the catalogued flux. The source may be fading, at the 1.0-sigma level. A SIMBAD object `WISEA J122501.45-521614.6' is 1.5" away. There are 2 2MASS objects within the source's 3-sigma error radius. All fluxes are 0.3-10 keV, observed. For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2 and photon index (Gamma)=1.7 unless otherwise stated. This is most likely a stellar flare of a Young Stellar Object Candidate Gaia DR3 6077506855610363648 (GCN 40523, Song et al.) The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/EP. This circular is an officicial product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40528. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...