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: The two primary Astra fleets are located at 19.2° and 28.2° East comprised of Astra 1KR, 1L, 1M and 2C at 19.2° E and Astra 2A, 2B, 2D and 1N at 28.2° E. An effort is underway to establish a third fleet at orbital position 23.5° East to further serve the central European markets with respect to digital TV and radio for both the DTH and cable markets as well as multimedia and interactive services. The first satellite to occupy this new orbital slot was Astra 3A and which was launched on March 29, 2002 from Kourou, French Guyana using an Ariane 44L rocket, weighing 1.500 tons and featuring 20 Ku-band transponders. With a proposed lifetime of 10 years, Astra 3A is now nearing its mission and is about to be replaced by Astra 3B and which is already in place also at the 23.5° East orbital slot.
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).
Astra 3 A
Mar 29, 2002
Nov 02, 2012
21:50 - 22:07 UT+2
AP 305/f3.8 Riccardi-Honders
AP 1200GTO GEM
SBIG LRGB filters
1.21" per pixel