GCN Circular 29092
Subject
GRB 201214A: Swift-XRT afterglow detection
Date
2020-12-19T19:28:30Z (3 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), T. Sbarrato (INAF-OAB), P.
D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), B. Sbarufatti (PSU)
and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has conducted further observations of the field of the
INTEGRAL-detected burst GRB 201214A (Mereghetti et al. GCN Circ.
29037). The observations now extend from T0+5.3 ks to T0+378.1 ks. The
source previously reported by Kennea et al. (GCN Circ. 29048), "Source
2", is fading with 3-sigma significance, and is therefore likely the
GRB afterglow. Using 2671 s of PC mode data and 4 UVOT images, we find
an enhanced XRT position (using the XRT-UVOT alignment and matching
UVOT field sources to the USNO-B1 catalogue): RA, Dec = 170.92446,
+33.86930 which is equivalent to:
RA (J2000): 11h 23m 41.87s
Dec(J2000): +33d 52' 09.5"
with an uncertainty of 2.2 arcsec (radius, 90% confidence). This
position is 36 arcsec from the INTEGRAL position. The source is fading
with alpha >0.6.
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.7 (+0.9, -0.7). The
best-fitting absorption column is 1.9 (+2.2, -1.6) x 10^21 cm^-2, in
excess of the Galactic value of 2.4 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 2.6 x 10^-11 (2.6 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.9 (+2.2, -1.6) x 10^21 cm^-2
Galactic foreground: 2.4 x 10^20 cm^-2
Excess significance: 1.8 sigma
Photon index: 2.7 (+0.9, -0.7)
The results of the XRT-team automatic analysis of the likely afterglow
are at https://www.swift.ac.uk/ToO_GRBs/00021406/Source2.php.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021406.
This circular is an official product of the Swift-XRT team.