TITLE:   GCN CIRCULAR
NUMBER:  29678
SUBJECT: GRB 210321A: Swift-XRT observations
DATE:    21/03/21 08:24:08 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M. Perri (SSDC & INAF-OAR), 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 210321A at 07:59:21.6 UT,
2730.6 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 87.89627, 70.13042
which is equivalent to:
   RA(J2000)  = 05h 51m 35.10s
   Dec(J2000) = +70d 07' 49.5"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 49 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.13 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 4
(+3.35/-2.86) x 10^21 cm^-2 (90% confidence).