The Hubble flow: an observer's perspective
  In this methodological note we discuss some details and peculiarities of the
cosmic expansion as viewed by a realistic observer. We show that the velocity
$v_\Theta$ related to a change (measured by observer's clock) of the angular
distance, plays an important role in formation of a meaningful observed picture
of the expansion of the universe. Usage of this velocity and the angular
distance (in addition to the standard approach --- proper distance and
corresponding velocity) allows to present the cosmic expansion in a more
illustrative manner. These parameters play a key role in visualization of the
expansion.
