TITLE: GCN CIRCULAR NUMBER: 26699 SUBJECT: ANTARES 200108A: No detection by Swift-XRT DATE: 20/01/10 16:19:42 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), A. Tohuvavohu (U. Toronto), J.A. Kennea (PSU) and S.B. Cenko (GSFC) report on behalf of the Swift/XRT team: Swift performed a series of 19 observations tiling the sky area of the Fermi-LAT / ANTARES coincident event ANTARES 200108A (Turley et al., GCN Circ. 26674). The observations were centred on RA=02h 49m 56.5s, Dec=-18d 05' 17", with a radius of ~50', and were carried out between 22:53:41 UT on Jan 8 until 00:37:14 UT on Jan 9; the detection of GRB 200109A subsequently interrupted the campaign. We gathered between 30 s and 150 s of exposure per tile, with the typical exposure being 110 s. No X-ray sources were found, with a typical upper limit of 0.06 ct/sec (0.3-10 keV). Assuming a standard AGN spectrum (NH=3e20, Gamma=1.7) this corresponds to a 0.3-10 keV observed flux of 2.6 x 10^-12 erg/cm^-2 s^-1.