GCN Circular 24863

N. P. M. Kuin (UCL-MSSL), A. A. Breeveld (MSSL-UCL),  C. Gronwall (PSU),
F. E. Marshall (NASA/GSFC), S. R. Oates (Uni. of Warwick), M.J. Page
(UCL-MSSL),
M. de Pasquale (Istambul U), M. H. Siegel (PSU), A. D'Ai (INAF-IASFPA),
P. D'Avanzo (INAF-OAB), 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), V. D'Elia(ASDC), P. A. Evans (U. Leicester),
P. Giommi (ASI), D. Hartmann (Clemson U.), J. A. Kennea (PSU),
H. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC), D. B. Malesani (DTU Space),
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), G. Tagliaferri (INAF-OAB), A. Tohuvavohu
(PSU),
and E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team:

The Swift UVOT instrument started follow up observations of the
LIGO-Virgo event S190426c (LVC GCN Circ. No. 24237) at 2019-04-26 17:45:00
UT
142 minutes after the event. Observations continued for about 48 hours
(Tohuvavohu et al., GCN Circ. No. 24353).

The UVOT approach for searching for the ultraviolet-optical counterpart has
been described in Kuin et al. (GCN Circ. No. 24767). The limiting magnitude
can vary but typically is 18.6th magnitude (Vega).  In the 894 fields that
were observed, UVOT detected 1008 galaxies and 130 counterpart candidates
but none of the counterpart candidates from the automated processing proved
to be a viable source. Neither did the additional inspection of the imaged
galaxies lead to a candidate missed by the automated processing.