GCN Circular 29457

A. A. Breeveld (UCL-MSSL) and S. L. Laha (GSFC/UMBC/CRESST) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210210A 85 s after the BAT trigger 
(Laha et al., GCN Circ. 29444
Not found
 
 
). A fading source consistent with the XRT position
(Goad et al. GCN Circ. 29448
Not found
 
 
) is detected in the initial UVOT exposures, as also detected by Lipunov 
et al. (GCN Circ. 29447
Not found
 
 
) and de Ugarte Postigo et al. (GCN Circ. 29450
Not found
 
 
).

The preliminary UVOT position is:
     RA  (J2000) =  17:31:05.01 = 262.77088 (deg.)
     Dec (J2000) = +14:39:46.4  =  14.66290 (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 first finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white_FC            85          235          147         16.04 �� 0.03
white              878         1028          147         16.57 �� 0.06
v                  629          648           20         16.95 �� 0.19
b                  553          573           20         16.99 �� 0.11
u                  298          547          246         15.91 �� 0.03
w1                 679          699           19         16.05 �� 0.15
m2                 827          847           19         16.13 �� 0.20
w2                 779          798           20         16.35 �� 0.18

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of 
E(B-V) = 0.097 in the direction of the burst (Schlegel et al. 1998).