[vsnet-grb-info 14947] GRB 140509A: Swift/UVOT Detection and photo-z

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16241
SUBJECT: GRB 140509A: Swift/UVOT Detection and photo-z
DATE:    14/05/09 17:42:38 GMT
FROM:    Frank Marshall at GSFC  <femarsha at khamseen.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) 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 140509A
121 s after the BAT trigger (Page et al., GCN Circ. 16230).
A source consistent with the XRT position
(Beardmore et al. GCN Circ. 16233)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  03:06:22.69 =  46.59456 (deg.)
    Dec (J2000) = -62:38:21.7  = -62.63935 (deg.)
with an estimated uncertainty of 0.42 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              121          271          147         17.00 +/- 0.03
v                  610          630           20         16.50 +/- 0.13
b                  536          556           20         17.04 +/- 0.10
u                  280          530          246         16.35 +/- 0.03
w1                 659         7011          490        >20.6
m2                 634         6806          490        >21.1
w2                 585         6396          432        >20.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).

The lack of detections in the UV filters suggests a redshift of about 2.4.