[vsnet-grb-info 27452] GRB 210217A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29555
SUBJECT: GRB 210217A: Swift/UVOT Detection
DATE:    21/02/23 14:27:28 GMT
FROM:    Kira Simpson at PSU  <kira.simpson1984 at gmail.com>

GRB 210217A: Swift/UVOT Detection

K. K. Simpson (PSU) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210217A
103 s after the BAT trigger (Simpson et al., GCN Circ. 29521).
A source consistent with the XRT position
*** POSITION REFERENCE is GCN_Notice ***
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  06:30:19.90 =  97.58291 (deg.)
    Dec (J2000) = +68:43:30.6  =  68.72517 (deg.)
with an estimated uncertainty of 0.46 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              103          253          147         18.80 +/- 0.06
u                  315          508          190         18.64 +/- 0.11

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.102 in the direction of the burst
(Schlegel et al. 1998).