[vsnet-grb-info 26645] GRB 201021C: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28745
SUBJECT: GRB 201021C: Swift/UVOT Detection
DATE:    20/10/22 13:16:47 GMT
FROM:    Samantha Oates at MSSL  <samantha.oates at alumni.ucl.ac.uk>

S. R. Oates (U.Birmingham) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 201021C
105 s after the BAT trigger (Lien et al., GCN Circ. 28730).
A source consistent with the XRT position
(Beardmore et al. GCN Circ. 28736)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
 RA  (J2000) =  00:50:06.93 =  12.52886 (deg.)
 Dec (J2000) = -55:51:56.8  = -55.86577 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).

Preliminary detections 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)      105          255         147         16.66 +/- 0.03
white              598          617           19         16.22 +/- 0.05
v                    647          667           19         16.49 +/- 0.16
b                    573          593           20         16.80 +/- 0.10 
u  (FC)           317          567         246         15.76 +/- 0.03 
u                    722          742           19         16.06 +/- 0.10
uvm2             672          692           19         16.43 +/- 0.24       
uvw2             623          643           19         16.68 +/- 0.22

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).