[vsnet-grb-info 25502] GRB 200416A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27602
SUBJECT: GRB 200416A: Swift/UVOT Detection
DATE:    20/04/18 06:40:43 GMT
FROM:    Kira Simpson at PSU  <kira.simpson1984 at gmail.com>

GRB 200416A: Swift/UVOT Detection

K. K. Simpson (PSU) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 200416A
102 s after the BAT trigger (Evans et al., GCN Circ. 27591).
A source consistent with the XRT position
(Evans GCN Circ. 27594)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  22:22:47.84 = 335.69934 (deg.)
    Dec (J2000) = -07:31:06.0  =  -7.51833 (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              102          252          147         16.57 +/- 0.03
v                  644          664           19         17.05 +/- 0.32
b                  570          590           20         17.48 +/- 0.20
u                  314          564          246         16.44 +/- 0.04
w1                 694          714           20         16.59 +/- 0.23
m2                 668          688           19        >16.3
w2                 620          640           19        >17.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.06 in the direction of the burst
(Schlegel et al. 1998).