TITLE: GCN CIRCULAR NUMBER: 23935 SUBJECT: GRB 190305A: Swift-XRT observations DATE: 19/03/06 15:43:43 GMT FROM: Valerio D'Elia at ASDC A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the AGILE and MAXI detected burst GRB 190305A (Ursi et al. GCN Circ. 23930, Nakahira et al. GCN Circ.23933) in a series of observations tiled on the sky. The total exposure time is 4.4 ks, distributed over 7 tiles; the maximum exposure at a single sky location was 1.4 ks. The data were collected between T0+31.9 ks and T0+43.5 ks, and are entirely in Photon Counting (PC) mode. Six uncatalogued X-ray sources have been detected. Source 1 is significantly brighter than the other candidates and it is marginally above the RASS limit, although, at the moment, we cannot assess if it is fading. Details of these sources are given below: Source 1: RA (J2000.0): 11.62657 = 00:46:30.38 Dec (J2000.0): -50.34865 = -50:20:55.1 Error: 2.5 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: 0.100 +/- 0.014 ct s^-1 Distance: 1069 arcsec from MAXI position. Flux: (4.79 +/- 0.67)e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 2: RA (J2000.0): 10.5180 = 00:42:4.32 Dec (J2000.0): -50.1058 = -50:06:20.9 Error: 6.9 arcsec (radius, 90% conf.) Count-rate: 0.0109 [+0.0066, -0.0047] ct s^-1 Distance: 1875 arcsec from MAXI position. Source 3: RA (J2000.0): 11.5149 = 00:46:3.57 Dec (J2000.0): -49.9843 = -49:59:03.4 Error: 6.5 arcsec (radius, 90% conf.) Count-rate: 0.0172 [+0.0055, -0.0045] ct s^-1 Distance: 649 arcsec from MAXI position. Flux: (1.07 [+0.34, -0.28])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 4: RA (J2000.0): 10.8580 = 00:43:25.92 Dec (J2000.0): -50.1848 = -50:11:05.2 Error: 7.7 arcsec (radius, 90% conf.) Count-rate: 0.0208 [+0.0085, -0.0067] ct s^-1 Distance: 1113 arcsec from MAXI position. Flux: (7.6 [+3.1, -2.5])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 5: RA (J2000.0): 11.1918 = 00:44:46.04 Dec (J2000.0): -49.9995 = -49:59:58.1 Error: 9.8 arcsec (radius, 90% conf.) Count-rate: (5.5 [+4.0, -2.7])e-3 ct s^-1 Distance: 538 arcsec from MAXI position. Source 6: RA (J2000.0): 10.7329 = 00:42:55.89 Dec (J2000.0): -49.9464 = -49:56:47.0 Error: 12.4 arcsec (radius, 90% conf.) Count-rate: (9.5 [+5.8, -4.2])e-3 ct s^-1 Distance: 1515 arcsec from MAXI position. The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00077. This circular is an official product of the Swift-XRT team.