TITLE:   GCN CIRCULAR
NUMBER:  29271
SUBJECT: GRB 210102B: further Swift-XRT observations
DATE:    21/01/06 17:28:28 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>

P. D'Avanzo, M.G. Bernardini, A. Melandri, T. Sbarrato (INAF-OAB), P.A. Evans (U. Leicester) 
and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift-XRT team:

Swift-XRT obtained further observations of the field of the MAXI-detected burst GRB 210102B 
(Guo et al. GCN Circ. 29223). The data were collected between T0+209.5 ks and T0+312.5 ks 
for a total exposure time of 2.5 ks, and are entirely in Photon Counting (PC) mode. 

Source 1 (Burrows et al., GCN Circ. 29230) is not detected down to a 3sigma upper limit of 0.004 ct/s. 
The source therefore has faded (with 2.2 sigma significance) with respect to the previous detection level 
(0.030 [+0.016, -0.012] ct s^-1 between T0+19.7 ks and T0+26.0 ks; Burrows et al., GCN Circ. 29230). 

We propose this source as the GRB X-ray afterglow, in agreement with the results of the optical observations 
reported by Pozanenko et al. (GCN Circ. 29270).