Difference: GCNCIRCULAR21733 ( vs. 1)

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 a series of 525 observations, covering 497 separate locations within the LVC error region for the GW trigger G299232 convolved with the 2MPZ catalogue (Bilicki et al. 2014, ApJS, 210, 9), using the 'bayestar-HLV' GW localisation map. The observations currently span from 11 ks to 256 ks after the LVC trigger.

We have detected an uncatalogued source with the Swift/UVOT, at the position:

RA(J2000) = 01h 40m 08.55s Dec(J2000)= +34d 34' 03.6"

We obtain the following magnitude using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373):

Filter Exp(s) Mag

u 57 18.00 +/- 0.16

The 57-s exposure started at 2017-08-27 T12:02:34 (about 1.95 days after the LVC trigger).

The magnitude is 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).

No X-ray source was detected at this position, with a 0.3-10 keV upper limit of 0.13 ct/sec, which corresponds to 5.2e-12 erg/cm^2/s (assuming a typical AGN spectrum).

There is no source in the DSS or SDSS at this position and there is no minor planet at this position.

Further Swift observations are planned.

-- DeepChatterjee - 28 Aug 2017