TITLE:   GCN CIRCULAR
NUMBER:  23141
SUBJECT: GRB 180809A: further Swift/XRT observations
DATE:    18/08/15 14:06:39 GMT
FROM:    Valerio D'Elia at ASDC  <valerio.delia@ssdc.asi.it>

V. D'Elia (SSDC) reports on behalf of the Swift/XRT team:

Swift performed a second visit to the field of the  MAXI-detected burst GRB 180809A (Yatabe et al. GCN Circ. 23103). The XRT data comprise 3700 s of exposure time, acquired ~5 days after the GRB trigger and entirely in PC mode. 

No excess is found at the position of the candidate afterglow reported by D'Elia et al. (GCN Circ. 23106), down to a three sigma upper limit of ~4E-3 cts/s, corresponding to a 0.3-10 keV observed flux of ~1E-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum). We thus conclude that the source reported by D'Elia et al. (GCN Circ. 23106) was indeed the X-ray counterpart of the MAXI GRB 180809A.

This circular is an official product of the Swift/XRT team