[vsnet-grb-info 6818] Swift UVOT observations of GRB081024B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8413
SUBJECT: Swift UVOT observations of GRB081024B
DATE:    08/10/26 17:44:33 GMT
FROM:    Patricia Schady at MSSL/Swift  <msslba at yahoo.co.uk>

P. Schady (MSSL/UCL) and C. Guidorzi (INAF-OAB) report on behalf of the Swift UVOT team.

The Swift UltraViolet/Optical Telescope (UVOT) began observations of Fermi-LAT GRB 081024B (Omodei et al., GCN Circ. 8407) 70.3 ks after the trigger.

Source 1 and Source 2 in GCN Circ. 8410 (Guidorzi et al.) are outside the UVOT field of view, and no new source is detected at the position of Source 3 (GCN Circ 8410; Guidorzi et al.) down to the following 3 sigma upper limits:

Filter   Tstart(dys)  Exp(s)  3-sigma UL
v         1.215        885     > 20.33
b         0.824        864     > 21.26
u         0.814        2641    > 21.42
uvw1      0.894        1531    > 21.07
uvm2      0.883        2548    > 21.36
uvw2      1.163        1201    > 21.07
 
The values quoted above are on the UVOT Photometric System (Poole et al, 2008, MNRAS 383,627). They are not corrected for the expected Galactic extinction corresponding to a reddening of E(B-V)=0.07 mag in the direction of the burst (Schlegel et al. 1998).