M. Perri (ASDC), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), D.N. Burrows
(PSU), J. D. Gropp (PSU), J.A. Kennea (PSU), J.P. Osborne (U.
Leicester), K.L. Page (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 INTEGRAL-detected
burst GRB 200424A (Mereghetti et al. GCN Circ. 27634), collecting 5.0
ks of Photon Counting (PC) mode data between T0+13.2 ks and T0+30.7 ks.
One uncatalogued X-ray source has been detected consistent with being
within the INTEGRAL position, however it is below the RASS limit and
shows no definitive signs of fading. Therefore, at the present time we
cannot confirm this as the afterglow. Details of this source are given
RA (J2000.0): 307.5055 = 20:30:01.31
Dec (J2000.0): -39.7001 = -39:42:00.5
Error: 3.0 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: (8.3 [+1.7, -1.6])e-3 ct s^-1
Distance: 22 arcsec from INTEGRAL position.
Flux: (2.68 [+0.55, -0.52])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Seven uncatalogued sources were also detected too far from the GRB
position to be likely afterglow candidates.
The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
This circular is an official product of the Swift-XRT team.