5. FULL-SKY PECULIAR VELOCITY SURVEYS
Given the uncertainty introduced by possible zero-point differences
between the samples making up the
Mark III dataset, how can the bulk flows on large scales best be
measured? The ideal way is with a
peculiar survey of galaxies covering the entire sky, observed in as
uniform a way as possible. In particular, the survey should
- have full-sky, uniform sampling in angle and redshift;
- have well-defined, simple, and easily modeled selection criteria;
- use a distance indicator with small intrinsic dispersion;
- use uniform observing techniques between North and South, Spring
and Fall, with much repeat observations.
There are a number of surveys just completed or in progress now which
approach this ideal. In particular:
- Roth 
have carried out a Tully-Fisher study of a full-sky volume-limited
sample of 140 IRAS galaxies to 4000 km s-1. A bulk
flow analysis has not yet been done,
although the data have been compared to the IRAS predicted
velocity field, and have found
consistency for the relatively small value of
- The EFAR collaboration
has carried out a Dn -
study of over 700
in 84 clusters in the Hercules-Corona Borealis, and Perseus-Pisces-Cetus
directions in the
redshift range 6000 < cz < 15000 km s-1, with
the aim of constraining the velocity fields in these superclusters.
- Hudson et al. (in preparation) are extending the EFAR survey
with measurements of Dn -
distances to 6-10 ellipticals in those clusters in the Lauer-Postman
with redshifts cz < 12,000 km s-1.
- Fruchter, Moore & Steidel (in preparation) are doing wide-field
photometry of a subsample
of the Lauer-Postman clusters; a fit of the photometry to a Schechter
function then yields a distance.
- J. Willick has measured Tully-Fisher distances to 20 spirals in
each of 15 clusters of galaxies over the sky, at cz
s-1. Analysis is in progress.
- Giovanelli et al. are measuring Tully-Fisher distances to
spiral galaxies both in the field and in
clusters over a large fraction of the sky to redshifts of 6000 km
s-1 and greater; see Giovanelli in this volume.
There are two further surveys in which I am involved, which I describe
in the following two sections.