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THE ASTRONOMER Electronic Circular No 3710      2022 May 28 10.21UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK      Backup: gmh@wdcc1.bnsc.rl.ac.uk
WORLD WIDE WEB                         http://www.theastronomer.org
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GRB 220527A AFTERGLOW 

B. Sbarufatti (PSU), et. al. report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the Fermi/LAT-detected
burst GRB 220527A mode data between T0+30.1 ks and T0+31.9 ks. 

Two uncatalogued X-ray sources are detected, of which one ("Source 2") is
above the RASS 3-sigma upper limit at this position, and is therefore likely
the GRB afterglow. Using 1733 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 (J2000): 21h 34m 06.73s Dec(J2000): 14d 58' 18.6"

with an uncertainty of 2.6 arcsec (radius, 90% confidence). This position is
4.9 arcmin from the Fermi/LAT position.  The light curve is consistent with
a constant source of mean count rate 3.9e-01 ct/sec. A power-law fit gives
an index of 0.6 (+2.5, -1.1).

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021503.
The results of the full analysis of the XRT observations are available at
https://www.swift.ac.uk/ToO_GRBs/00021503.



On GCN CIRCULAR 32143

S. de Wet (UCT), P.J. Groot (Radboud/UCT/SAAO) and P.M. Vreeswijk (Radboud)
report on behalf of the MeerLICHT consortium:

Following the detection of GRB 220527A by AGILE (Ursi et al., GCN 32129),
Fermi/GBM (Fermi GBM Team, GCN 32130) and Fermi/LAT (Bissaldi et al., GCN
32131), the 0.6m wide-field MeerLICHT telescope, located at Sutherland,
South Africa, obtained 2x600 s exposures in the q-band and a single 300 s
exposure in each of the g and r bands covering the entire Fermi/LAT error
region beginning 17.68 hours after the GRB trigger.

We detect the previously reported afterglow to GRB 220527A (Sbarufatti et
al., GCN 32135; Tohuvavohu, GCN 32136; Imai et al., GCN 32138; Xu et al.,
GCN 32141) at the UVOT position with AB magnitudes:

g = 19.72 +/- 0.04
r = 19.55 +/- 0.06
q = 19.57 +/- 0.02

Guy M Hurst



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Guy M Hurst
16 Westminster Close, Basingstoke, Hampshire, RG22 4PP, England
Tel/FAX (01256) 471074 Internet: guy@tahq.org.uk
Mobile: (07905) 332226 Personal WWW: http://www.guyhurst.co.uk
Editor of The Astronomer                       http://www.theastronomer.org 
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