[vsnet-grb-info 20783] GRB 180630A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22881
SUBJECT: GRB 180630A: Swift/UVOT Detection
DATE:    18/07/02 01:46:46 GMT
FROM:    Sam LaPorte at PSU  <sjl5346 at psu.edu>

GRB 180630A: Swift/UVOT Detection

S. J. LaPorte (PSU) and P. D'Avanzo (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180630A
88 s after the BAT trigger (D'Avanzo et al., GCN Circ. 22872).
A fading source consistent with the XRT position
(Beardmore et al. GCN Circ. 22873)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  03:15:55.74 =  48.98224 (deg.)
    Dec (J2000) = -87:28:42.3  = -87.47842 (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               88          237          148         17.49 +/- 0.04
white             6384         6584          196         19.50 +/- 0.11
v                  629         1597          117         18.56 +/- 0.20
b                  555          748           39         18.76 +/- 0.19
u                  300          549          246         17.76 +/- 0.06
w1                 678         7392          510         19.42 +/- 0.17
m2                 654         7187          452         20.16 +/- 0.33
w2                 605         6777          255        >19.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.13 in the direction of the burst
(Schlegel et al. 1998).