GCN Circular 29790

A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A.
Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester),
J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato
(INAF-OAB) and	report on behalf of the Swift-XRT team: report on
behalf of the Swift-XRT team:

We have analysed 4.4 ks of XRT data for GRB 210410A, from 61 s to 52.6
ks after the  BAT trigger. The data comprise 115 s in Windowed Timing
(WT) mode (the first 8 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. Using 702 s of PC mode data and
1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 269.75437, +45.36192 which is equivalent to:

RA (J2000): 17h 59m 01.05s
Dec(J2000): +45d 21' 42.9"

with an uncertainty of 2.4 arcsec (radius, 90% confidence).

The late-time light curve (from T0+4.3 ks) can be modelled with a
power-law decay with a decay index of alpha=1.5 (+0.5, -0.4).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.33 (+/-0.11). The
best-fitting absorption column is  1.4 (+0.5, -0.4) x 10^21 cm^-2, in
excess of the Galactic value of 4.0 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.47 (+0.18, -0.16)
and a best-fitting absorption column of 7.2 (+6.0, -3.2) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.5 x 10^-11 (4.9 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     7.2 (+6.0, -3.2) x 10^20 cm^-2
Galactic foreground: 4.0 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.47 (+0.18, -0.16)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01042113.

This circular is an official product of the Swift-XRT team.