  The meaning of "linear expansion" is explained. Particularly accurate
relative distances are compiled and homogenized a) for 246 SNe Ia and 35
clusters with v<30,000 km/s, and b) for relatively nearby galaxies with 176
TRGB and 30 Cepheid distances. The 487 objects define a tight Hubble diagram
from 300-30,000 km/s implying individual distance errors of <7.5%. Here the
velocities are corrected for Virgocentric steaming (locally 220 km/s) and - if
v_220>3500 km/s - for a 495 km/s motion of the Local Supercluster towards the
warm CMB pole at l=275, b=12; local peculiar motions are averaged out by large
numbers. A test for linear expansion shows that the corrected velocities
increase with distance as predicted by a standard model with q_0=-0.55
[corresponding to (Omega_M, Omega_Lambda)=(0.3,0.7)], but the same holds - due
to the distance limitation of the present sample - for a range of models with
q_0 between ~0.00 and -1.00. For these models H_0 does not vary systematically
by more than +/-2.3% over the entire range. Local, distance-dependent
variations are equally limited to 2.3% on average. In particular the proposed
Hubble Bubble of Zehavi et al. and Jha et al. is rejected at the 4sigma level.
- Velocity residuals in function of the angle from the CMB pole yield a
satisfactory apex velocity of 448+/-73 km/s and a coherence radius of the Local
Supercluster of ~3500 km/s (~56 Mpc), beyond which galaxies are seen on average
at rest in co-moving coordinates with respect to the CMB. Since no obvious
single accelerator of the Local Supercluster exists in the direction of the CMB
dipole its motion must be due to the integral gravitational force of all
surrounding structures. Most of the gravitational dipole comes probably from
within 5000 km/s.
