TITLE:   GCN CIRCULAR
NUMBER:  23049
SUBJECT: GRB 180728A: Swift-XRT observations
DATE:    18/07/28 19:29:20 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M. Perri (ASDC), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU) and G. Cusumano
(INAF-IASF PA) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 180728A at 17:57:51.5 UT,
1730.8 seconds after the BAT trigger. XRT found a bright, uncatalogued
X-ray source located at RA, Dec 253.5648, -54.0437 which is equivalent
to:
   RA(J2000)  = +16h 54m 15.55s
   Dec(J2000) = -54d 02' 37.3"
with an uncertainty of 5.8 arcseconds (radius, 90% containment). This
location is 46 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy.

The initial flux in the 2.5 s image was 7.92e-10 erg cm^-2 s^-1 (0.2-10
keV).