re: Accurate GEO Obs plus GEO UNID
Philip Chien (kc4yer@amsat.org)
Fri, 31 Oct 1997 11:33:20 -0400
Ron Lee <ronlee@pcisys.net> said:
>Observed six geosynch satellites tonight to get data for the
>SDP4 issue. Used Mike McCants ALLDAT file from 25 Oct 97
>(the current one on his web site)
>
>Name NORAD Time(UT) RA (HH:MM.M) Dec (DD:MM) (J2000)
>ACTS 22796 03:14:03.3 23:14.4 -06:11
>DBS 2 23192 03:17:28.7 23:14.6 -06:06
>DBS 3 23598 03:17:57.5 23:14.6 -06:06
>ASC 2 21227 03:18:18.2 23:14.6 -06:06
>DBS 1 22930 03:18:31.5 23:14.6 -06:06
>UNID xxxxx 03:19:35.1 23:14.6 -06:06
>
>The declination was not exactly the same (-06:06). Will have
>to get a better obs to 0.2 arcmin in Dec if required. Note the
>non DBS satellite (ASC 2) stuck between the DBS satellites.
>Must belong to the same folks.
>
>Could not ID the UNID geosynch in any of my elsets. If anyone
>else can, please advise.
The geosync longitude you viewed is approximately 101 degrees West.
AMSC 1 (23553 1995 19A) is also located at that position. It's a
three-axis stabilized satellite with *large* L-Band antennas for mobile
communications. While I don't have its exact Ra/Dec for your location it's
a good bet for your Unid. AMSC = American Mobile Satellite Corporation.
Nice launch from what I recall.
ASC-2 (now known as Spacenet 4 21227, 1991-28A) is located at 101 West
which puts it in the middle of the DBS satellites. But Spacenet 4 has C
and Ku band broadcast transponders while the DBS satellites use a slightly
higher Ku frequencies which are alotted to the DBS companies. Spacenet 4
is owned by GE Americom which is not associated with DirecTV/USSB which
owns the DBS birds.
I watch Spacenet 4 from time-to-time on my real satellite dish. It
transmits the Starz! movie channels, west coast network feeds from San
Francisco (CBS), Los Angeles (NBC), and Seattle (ABC). It also has various
niche sports channels and a couple of 'barker' promo channels. But it's
one of the less powerful broadcast band satellites serving the U.S.
It isn't difficult to have many satellites share the same orbital location
as long as they're on different bands, or use some other system to avoid
interference. ACTS (Advanced Communications Technology Satellite) is a
Ka-Band (20/30 Ghz.) experimental satellite. In the case of the DBS
satellites they're all owned by the same company, so different satellites
use different frequencies. If a DBS satellite was to fail then the other
satellite would turn on its transponders with the same frequencies, but
would have to reduce the overall output power.
Naturally the exact satellite locations are slightly off (to avoid
collisions) but from the point of view of a satellite dish on the ground
they're all occupying the same spot in the sky.
Hmm, I've seen four of those six satellite when they launched. And saw
ACTS in the shuttle payload canister on the ground before launch. Some
pretty nice souviners too - including an ASC-2 beach towel.
Philip Chien [M1959.05.31/31.145//KC4YER@amsat.org]