[vsnet-grb-info 19610] Correction to GCN Circular 21351: GRB 170714A: Swift/UVOT Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21353
SUBJECT: Correction to GCN Circular 21351: GRB 170714A: Swift/UVOT Observations
DATE:    17/07/17 21:37:38 GMT
FROM:    Frank Marshall at GSFC  <femarsha at khamseen.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) 
reports on behalf of the Swift/UVOT team:

Some of the Swift UVOT exposures of GRB 170714A
previously reported by Marshall and D'Ai (GCN Circular 21351)
contain readout streaks due to nearby bright sources.
These streaks make the determination of magnitudes very difficult,
and this effect was not accounted for in the previous analysis.
The affected exposures have been removed from the corrected
table given below. As a result, the most significant detection
of a source with UVOT has been removed, and there is now
only weak evidence for a UVOT source at the position of
the z-band afterglow candidate reported by
de Ugarte Postigo et al. (GCN Circ. 21346).

Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag
v                  397         1695          175         >18.6
b                  496         1644          155         20.0 +/- 0.33
b                92917        93309          382         >20.3
u                  471         1619          284         20.1 +/- 0.35
u                81432        92912         1509         >20.7
w1                 446         1594          136         >21.0
m2               76276        98985         2438         >21.3
w2               74458        86274         1771         >21.5

I apologize for any confusion caused by the earlier report.