GCN Circular 23049
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).