GCN Circular 37974

A.A. Breeveld (UCL-MSSL) and N. J. Klingler (GSFC/UMBC/CRESSTII) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 241030A 83s after the BAT trigger (Klingler et al., GCN Circ. 37956
Not found
 
 
) and Fermi/GBM trigger (Fermi GBM team, GCN Circ. 37955
Not found
 
 
).
A fading source consistent with the XRT position (Beardmore et al., GCN Circ. 37962
Not found
 
 
) and the optical counterpart (Watson et al., GCN 37957
Not found
 
 
; Fernández-Rodríguez et al., GCN 37958
Not found
 
 
; Zheng et al., GCN 37959
Not found
 
 
; An et al., GCN 37960
Not found
 
 
; Higuchi et al., GCN 37963
Not found
 
 
; Qiu et al., GCN 37965
Not found
 
 
 and Wu et al., GCN 37970
Not found
 
 
), is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  22:52:33.47 = 343.13946 (deg.)
    Dec (J2000) = +80:26:59.8  =  80.44995 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).

Preliminary detections 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               83          232          147         15.43 ± 0.02
white              575          595           19         13.80 ± 0.05
white              748          768           20         14.19 ± 0.04
v                  625          645           19         13.71 ± 0.05
b                  551          571           20         13.96 ± 0.04
u                  295          545          246         12.96 ± 0.02
w1                 674          694           20         14.09 ± 0.06
m2                 650          670           20         14.57 ± 0.10
w2                 601          621           20         15.34 ± 0.11

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.131 in the direction of the burst (Schlegel et al. 1998).