[vsnet-grb-info 18741] GRB 161117A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20190
SUBJECT: GRB 161117A: Swift/UVOT Detection
DATE:    16/11/17 23:04:40 GMT
FROM:    Frank Marshall at GSFC  <femarsha at khamseen.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) and J. R. Cummings (NASA/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 161117A
69 s after the BAT trigger (Cummings et al., GCN Circ. 20179).
A source consistent with the XRT position
(Goad et al., GCN Circ. 20184)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  21:28:12.55 = 322.05230 (deg.)
    Dec (J2000) = -29:36:49.1  = -29.61365 (deg.)
with an estimated uncertainty of 0.44 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
in the table below. The lack of detections in the m2 and w2 filters
is consistent with the redshift of 1.549 reported by
Malesani et al. (GCN Circ. 20180).

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

white               69          219          147         18.26 +/- 0.05
v                  611         6146          255         18.77 +/- 0.19
b                  536         5531          236         19.42 +/- 0.17
u                  281          531          246         19.48 +/- 0.20
w1                 660         6556          255         19.48 +/- 0.25
m2                1064        13173          712        >20.2
w2                 586        11751         1141        >20.8

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).