Skip to main content
Introducing Einstein Probe, Astro Flavored Markdown, and Notices Schema v4.0.0. See news and announcements

GCN Circular 27754

GRB 200517A: Swift-XRT afterglow detection
2020-05-18T15:06:08Z (4 years ago)
Jeffrey Gropp at PSU <>
B. Sbarufatti (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo
(INAF-OAB), M.G. Bernardini (INAF-OAB), J. D. Gropp (PSU) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 200517A (Niwano et al. GCN Circ. 27750) in a series of
observations tiled on the sky. The total exposure time is 1.1 ks,
distributed over 7 tiles; the maximum exposure at a single sky location
was 388 s. The data were collected between T0+8.0 ks and T0+8.3 ks, and
are entirely in Photon Counting (PC) mode. 

An uncatalogued X-ray source is detected and is above the RASS limit,
and is therefore likely the GRB afterglow. Using 366 s of PC mode data
and 2 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 = 17.69837, -50.92242 which is equivalent to:

RA (J2000): 01h 10m 47.61s
Dec(J2000): -50d 55' 20.7"

with an uncertainty of 3.3 arcsec (radius, 90% confidence). This
position is 20.7 arcmin from the MAXI position.  We cannot determine at
the present time whether the source is fading.

The results of the XRT-team automatic analysis of the likely afterglow
are at
The results of the full analysis of the tiled XRT observations are
available at

This circular is an official product of the Swift-XRT team.
Looking for U.S. government information and services? Visit