  The emergence of time-domain multi-messenger (astro)physics requires for new,
improved ways of interchanging scheduling information, in order to allow more
efficient collaborations between the various teams. Currently space- and
ground-based observatories provide target visibilities and schedule information
via dedicated web pages in various, (observatory-specific) formats. With this
project we aim to: i) standardise the exchange of information about
observational schedules and instrument set-ups, and ii) standardise the
automation of visibility checking for multiple facilities. To meet these goals,
we propose to use VO protocols (ObsTAP-like) to write the services necessary to
expose these data to potential client applications and to develop visibility
servers across the different facilities.
