[vsnet-grb-info 20733] GRB 180623A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22831
SUBJECT: GRB 180623A: Swift/UVOT Detection
DATE:    18/06/24 13:58:14 GMT
FROM:    Paul Kuin at MSSL  <npkuin at gmail.com>

N. P. M. Kuin (UCL-MSSL) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180623A
86 s after the BAT trigger (Page et al., GCN Circ. 22828).
A source consistent with the XRT position (Evans et al. GCN Circ. 22829)
is detected in the initial UVOT exposures.

The UVOT refined position is ra, deg = 214.5288,-60.2541 deg which is
RA = 14:18:06.9
Dec = -60:15:14.8
with an estimated uncertainty of 1".

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               86          236          150        >20.68
white              878          997          119         20.04 +/- 0.24
v                  629         6296          432        >19.2
b                18042        18207          162         19.86 +/- 0.28
u                  299        17732         2252        >21.6
w1                 678        16819         1318        >20.8
m2                 653         6501          432        >20.0
w2                 604         6092          432        >20.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 7.04 in the direction of the burst
(Schlegel et al. 1998).