Roughly 500 geostationary satellites are currently placed in a static orbit (as viewed by a ground-based observer) about our planet at an
altitude ranging from 500 to 40,000 kilometers. The closest satellites orbitting the planet are believed to be spy satellites whereas most
distant are the geostationary group of satellites with an instrinsic magnitude of 11 or greater. As a result, due to their distance and faint
magnitude, geosats may be classified as the DSO's of the satellite world. At their high altitude not only can they virtually view the complete
globe below them but they also have the unique characteristic of having their orbital speed closely match the rotational speed of the earth
and, as such, give the impression to a ground-based observer of being stationary above the planet. These satellites have a wide range of
applications and functions and include remote sensing (Meteosat, GOES-East and GOES-West, GMS etc) and such telecommunication functions as
direct broadcast voice and video communications as well as live television coverage (Astra, Hot Bird, Telstar etc) by virtue of the fact they
can beam their signal from a "fixed" point in space relative to a ground source.
Note: AfriStar was launched on Oct 28, 1998 from Kourou, French Guyana using an Ariane 44L rocket. It weighs 2.739 tons, features 3 L-transponders and has an expected operational lifetime of fifteen years. The satellite provides digital audio and multi-media services to a very wide audience due to its very wide footprint and which includes Europe, the Middle East, Africa and Asia.
Note: The first image below represents a single one-minute exposure whereas the second image below is the sum of the fifteen one-minute exposures captured and which reveals some very slight motion for the four Astra satellites during the approximate 20-minute span and which quite often is characteristic of geosats (ex. due to inclination).
Oct 28, 1998
Nov 03, 2012
00:52 - 01:13 UT+2
AP 305/f3.8 Riccardi-Honders
AP 1200GTO GEM
SBIG LRGB filters
1.21" per pixel