TITLE: GCN CIRCULAR NUMBER: 43622 SUBJECT: GRB 260204A: Swift-XRT observations DATE: 26/02/05 13:29:09 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), S. Campana (INAF-OAB), M. Capalbi (INAF-OAR), 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 SVOM/ECLAIRs-detected GRB 260204A, collecting 1.7 ks of Photon Counting (PC) mode data between T0+23 ks and T0+25 ks after the trigger. We have detected 4 sources. These have been automatically classified as follows: * 0 likely counterparts * 0 candidate counterparts * 3 uncatalogued X-ray sources * 1 known X-ray source As already reported source 1 is consistent with an optical source (Li et al., GCN Circ. 43620; Malesani et al., GCN Circ. 43621). We note that, in the X-rays, this source is not well separated from source 3 and cannot rule out that these arise not from point sources but from a patch of diffuse emission. We note also the presence of a source in the XMM Slew survey XMMSL3 catalogue, XMMSL3 J134023.8+015613 at RA,Dec = 205.0888, +1.9370 degrees (J2000), with a 1-sigma error of 4.3" (statistical) and an estimated systematic error of ~8" (see http://xmmssc.irap.omp.eu/Catalogue/XMMSL3/XMMSL3_Catalogue_User_Guide.html#... ry). This source is 33" from the position of source 1. Source 2 is consistent with the position of HD 118981, a high proper motion star, while source 4 is a known quasar. Further observations are planned. Uncatalogued X-ray sources -------------------------- Source 1 (SWIFT J134025.4+015552): ================================== RA (J2000.0): 205.1060 = 13 40 25.44 Dec (J2000.0): +1.9313 = +01 55 52.7 Error: 5.0 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 5.4 arcmin from the SVOM/ECLAIRs position. Mean rate: 0.0235 +/- 0.0046 ct s^-1 Mean flux: (8.7 +/- 1.7)e-13 erg cm^-2 s^-1 Peak rate: 0.0235 +/- 0.0046 ct s^-1 Peak flux: (8.7 +/- 1.7)e-13 erg cm^-2 s^-1 ECF: 3.71e-11 erg cm^-2 ct^-1 assuming NH=1.90e+20 cm^-2, gamma=1.76 determined from a spectral fit. RASS UL: 4.1e-02 ct s^-1 (converted to XRT; 0.3-10 keV) so the source is not above this 3-sigma upper limit. There is no evidence for fading. Source 2 (SWIFT J134026.9+020905): ================================== RA (J2000.0): 205.1125 = 13 40 27.00 Dec (J2000.0): +2.1515 = +02 09 05.4 Error: 5.0 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 7.9 arcmin from the SVOM/ECLAIRs position. Mean rate: 0.0136 +/- 0.0036 ct s^-1 Mean flux: (2.28 +/- 0.61)e-13 erg cm^-2 s^-1 Peak rate: 0.0136 +/- 0.0036 ct s^-1 Peak flux: (2.28 +/- 0.61)e-13 erg cm^-2 s^-1 ECF: 1.67e-11 erg cm^-2 ct^-1 assuming NH=1.30e+22 cm^-2, gamma=9.94 determined from a spectral fit. RASS UL: 3.3e-02 ct s^-1 (converted to XRT; 0.3-10 keV) so the source is not above this 3-sigma upper limit. There is no evidence for fading. A SIMBAD object `HD 118981' is 0.7" away. There is 1 2MASS object within the source's 3-sigma error radius. Source 4 (SWIFT J134043.1+020310): ================================== RA (J2000.0): 205.1796 = 13 40 43.10 Dec (J2000.0): +2.0530 = +02 03 10.8 Error: 6.6 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 4.2 arcmin from the SVOM/ECLAIRs position. Mean rate: (7.2 [+2.9, -2.3])e-3 ct s^-1 Mean flux: (1.49 [+0.60, -0.48])e-13 erg cm^-2 s^-1 Peak rate: (7.2 [+2.9, -2.3])e-3 ct s^-1 Peak flux: (1.49 [+0.60, -0.48])e-13 erg cm^-2 s^-1 ECF: 2.07e-11 erg cm^-2 ct^-1 assuming NH=6.90e+21 cm^-2, gamma=9.20 determined from a spectral fit. RASS UL: 2.1e-02 ct s^-1 (converted to XRT; 0.3-10 keV) so the source is not above this 3-sigma upper limit. There is no evidence for fading. A SIMBAD object `[VV2006] J134042.9+020307' is 4.5" away. Known X-ray sources ------------------- Source 3 (SWIFT J134023.6+015612): ================================== RA (J2000.0): 205.0984 = 13 40 23.62 Dec (J2000.0): +1.9369 = +01 56 12.8 Error: 6.1 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 5.1 arcmin from the SVOM/ECLAIRs position. Mean rate: 0.0225 +/- 0.0058 ct s^-1 Mean flux: (2.54 +/- 0.65)e-12 erg cm^-2 s^-1 Peak rate: 0.0225 +/- 0.0058 ct s^-1 Peak flux: (2.54 +/- 0.65)e-12 erg cm^-2 s^-1 ECF: 1.13e-10 erg cm^-2 ct^-1 assuming NH=1.89e+20 cm^-2, gamma=1.04 determined from a spectral fit. This matches a catalogued X-ray source XMMSL3 J134023.8+015613 in the XMM-NEWTON/XMMSLEWCLN catalogue. Details: Separation: 1.6" from the XRT source Cat Rate: 4.8e-01 +/- 2.6e-01 ct s^-1 Cat Flux: 7.7e-12 +/- 4.1e-12 erg cm^-2 s^-1 (0.3-10 keV) so the source is not above the catalogued flux. There is no evidence for fading. There is 1 2MASS object 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. 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/SVOM/SVOM_FIELD00057. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43622. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...