J.P. Osborne (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (ASDC),
V. D'Elia (ASDC), A. Tohuvavohu (PSU), J.A. Kennea (PSU), B. Sbarufatti
(PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 190804B (Sato et al. GCN Circ. 25262) in a series of
observations tiled on the sky. The total exposure time is 1.3 ks,
distributed over 7 tiles; the maximum exposure at a single sky location
was 395 s. The data were collected between T0+37.2 ks and T0+38.6 ks,
and are entirely in Photon Counting (PC) mode.
Two uncatalogued X-ray sources have been detected, however none of them
is above the RASS limit or shows definitive signs of fading. Therefore,
at the present time we cannot identify which, if any, is the afterglow.
Details of these sources are given below:
RA (J2000.0): 239.7568 = 15:59:1.62
Dec (J2000.0): -44.6361 = -44:38:09.8
Error: 4.1 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: 0.031 [+0.014, -0.011] ct s^-1
Distance: 606 arcsec from MAXI position.
Flux: (1.38 [+0.60, -0.46])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)
RA (J2000.0): 240.0251 = 16:00:6.02
Dec (J2000.0): -44.7816 = -44:46:53.9
Error: 3.9 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: 0.113 [+0.038, -0.031] ct s^-1
Distance: 333 arcsec from MAXI position.
Flux: (5.1 [+1.7, -1.4])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)
The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00082.
This circular is an official product of the Swift-XRT team.