GCN Circular 17472

F. E. Marshall (NASA/GSFC) and C. Pagani (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150213B
153 s after the BAT trigger (Pagani et al., GCN Circ. 17464
Not found
 
 
).
A source consistent with the XRT position
(Osborne et al. GCN Circ. 17469
Not found
 
 
)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  16:53:48.67 = 253.45278 (deg.)
    Dec (J2000) = +34:11:19.3  =  34.18869 (deg.)
with an estimated uncertainty of 0.46 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              153          302          147         18.61 +/- 0.07
v                 4498        23548          966        >20.3
b                 3883        12039          961        >20.7
u                  310          532          218         18.76 +/- 0.15
w1                4910        10539         1082         20.76 +/- 0.21
m2                4703        16622         1224         21.25 +/- 0.32
w2                4293        22956         1279         21.48 +/- 0.31

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).