Globular Clusters in the Sagittarius stream. Revising members and
  candidates with Gaia DR2
  We reconsider the case for the association of Galactic globular clusters
(GCs) to the tidal stream of the Sagittarius dwarf spheroidal galaxy (Sgr
dSph), using Gaia DR2 data. We use RR Lyrae to trace the stream in 6D and we
select clusters matching the observed stream in position and velocity. In
addition to the clusters residing in the main body of the galaxy (M 54, Ter 8,
Ter 7, Arp 2) we confirm the membership of Pal 12 and Whiting 1 to the portion
of the trailing arm populated by stars lost during recent perigalactic
passages. NGC 2419, NGC 5634 and NGC 4147 are very interesting candidates,
possibly associated to more ancient wraps of the stream. We note that all these
clusters, with the exception of M 54, that lies within the stellar nucleus of
the galaxy, are found in the trailing arm of the stream. The selected clusters
are fully consistent with the [Fe/H] vs. [Mg/Fe], [Ca/Fe] patterns and the
age-metallicity relation displayed by field stars in the main body of Sgr dSph.
