[vsnet-grb-info 15931] GRB 141221A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17219
SUBJECT: GRB 141221A: Swift/UVOT Detection
DATE:    14/12/22 17:26:04 GMT
FROM:    Frank Marshall at GSFC  <femarsha at khamseen.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) and E. Sonbas (NASA/GSFC/Adiyaman Univ.)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 141221A
84 s after the BAT trigger (Sonbas et al., GCN Circ. 17206).
A source consistent with the enhanced XRT position
(Beardmore et al. GCN Circ. 17211)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  13:13:08.81 = 198.28672 (deg.)
    Dec (J2000) = +08:12:18.8  =   8.20522 (deg.)
with an estimated uncertainty of 0.43 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               84          234          147         17.33 ± 0.04
v                  626          646           19         17.43 ± 0.26
b                  552          571           20         17.92 ± 0.21
u                  296          546          246         17.62 ± 0.07
w1                4061         4261          197        >20.0
m2                3856        10742          414        >20.9
w2                6231         6399          165        >20.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).