TITLE:   GCN CIRCULAR
NUMBER:  24334
SUBJECT: LIGO/Virgo S190425z: VISTA K-band observations of the Swift/UVOT Transient
DATE:    19/04/28 21:30:26 GMT
FROM:    Nial Tanvir at U.Leicester  <nrt3@star.le.ac.uk>

N. R. Tanvir (U. Leicester), C. Gonzalez-Fernandez (IoA, U. Cambridge),
A. J. Levan (Radbound U.), D. B. Malesani (DAWN/NBI and DARK/NBI),
P. A. Evans (U. Leicester) report on behalf of the VINROUGE collaboration:

The location of the variable source reported in Swift/UVOT
observations (Breeveld et al., GCN 24296) appears in a field
imaged by the 4m VISTA telescope as part of our follow-up of the
binary neutron star merger S190425z (LVC collaboration, GCN 24168).
The observations were obtained on 2019-04-28 07:55 UT in the 2.15 um
Ks-filter.  We find no significant flux at the transient location,
corresponding to a 2-sigma limiting magnitude of K(AB)~20.6.
The absence of a detection in these observations suggests that
either it has rapidly faded and/or is not very red in UV-nIR colours.

The faint constant source, close to the UVOT position, noted by 
Palmese et al. (GCN 24312), is marginally visible in our imaging,
at about the 2-sigma level.