GCN Circular 28742
Subject
GRB 201020A: Swift/UVOT Observations
Event
Date
2020-10-22T12:16:21Z (5 years ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
M. H. Siegel (PSU) and E. Ambrosi (INAF-IASFPA)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 201020A
144 s after the BAT trigger (Ambrosi et al., GCN Circ. 28696).
We confirm the fading source initially reported by Ambrosi et al. and
since confirmed by numerous observations (Adachi et al., GCN
Circ. 28697; Fu et al., GCN Circ. 28701; Belkin et al., GCN Circ. 28703,
Pankow et al. GCN Circ. 28708, Kumar et al. GCN Circ. 28711, Paek et al.
GCN Circ. 28713). The afterglow is not detected in UVOT's NUV filters,
which would be consistent with the redshift of 2.9 reported by Kann et al.
(GCN Circ. 28717).
The preliminary UVOT position is:
RA (J2000) = 17:24:54.66 = 261.22773 (deg.)
Dec (J2000) = +31:25:42.1 = 31.42837 (deg.)
with an estimated uncertainty of 0.44 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white (fc) 145 294 147 18.19+/-0.05
white 583 775 38 19.39+/-0.23
white 9805 10713 885 19.71+/-0.09
white 131168 131712 531 >21.48
v 632 826 38 17.91+/-0.28
v 21653 22150 485 19.26+/-0.28
v 34473 35292 798 19.86+/-0.29
v 125782 126429 629 >19.99
b 558 750 38 >19.30
b 22822 23469 630 20.35+/-0.21
b 39219 39998 759 21.05+/-0.36
b 130256 131163 885 >20.60
u (fc) 303 552 245 19.76+/-0.27
u 706 726 19 >18.42
u 29427 29557 128 >19.69
uvw1 681 876 38 >18.16
uvw1 28521 29420 885 >20.42
uvm2 656 676 19 >17.06
uvm2 27614 28514 885 >20.29
uvw2 608 800 38 >18.04
uvw2 10719 34466 1329 >20.71
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).