TITLE:   GCN CIRCULAR
NUMBER:  21758
SUBJECT: LIGO/Virgo G299232: Further Swift/UVOT Observations of Optical Transient SwiftJ014008.5+343403.6
DATE:    17/08/29 22:55:12 GMT
FROM:    Samuel Emery at UCL-MSSL/Swift  <samuel.emery.15@ucl.ac.uk>

S.W.K. Emery (UCL-MSSL), A.A. Breeveld (UCL-MSSL), F.E. Marshall (NASA/GSFC),
S.R. Oates (Uni. of Warwick), N.P.M. Kuin (UCL-MSSL), S.D. Barthelmy (NASA/GSFC),
A.P. Beardmore (U. Leicester), D.N. Burrows (PSU), S. Campana (INAF-OAB),
S.B. Cenko (NASA/GSFC), G. Cusumano(INAF-IASF PA), A. D'Ai (INAF-IASFPA),
P. D'Avanzo (INAF-OAB), V.D'Elia(ASDC), P.A. Evans (U. Leicester),
P. Giommi (ASI), C. Gronwall (PSU), J.A. Kennea (PSU), H.A. Krimm (CRESST/GSFC/USRA),
A.Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB), J.A. Nousek (PSU), P.T. O'Brien (U. Leicester),
J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester),
D.M. Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), T. Sakamoto (AGU),
B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB),
A. Tohuvavohu (PSU), E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift team:

Swift has performed follow-up ToO observations of the optical transient SwiftJ014008.5+343403.6,
reported in Emery et al. (GCN 21733). We obtained 4 ks of data from 278 ks to 341 ks after the
LVC trigger. This source has faded and is no longer detected in any filter. Earlier MASTER observations
did not detect this source, see Lipunov et al. (GCN 21749). Other observatories have also not detected
the source (Tomasella et al. (GCN 21745); Pozanenko et al. (GCN 21754); Copperwheat et al. (GCN 21755);
Jonker et al. (GCN 21756); Butler et al. (GCN 21757)).

We obtain preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373):

Filter  Start time     Stop time   Exposure(s)   Magnitude(Vega)
   v     T0+278 ks     T0+341 ks      372            >20.1     
   b     T0+277 ks     T0+340 ks      372            >21.1     
   u     T0+277 ks     T0+340 ks      372            >20.7     
uvw1     T0+276 ks     T0+340 ks      745            >21.0     
uvm2     T0+278 ks     T0+341 ks      514            >20.5     
uvw2     T0+277 ks     T0+340 ks     1491            >21.6     

The magnitudes are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the source
(Schlegel et al. 1998).

Further Swift observations are planned.