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See Discovery/ISS in formation after un-docking



 
 
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  #1  
Old August 5th 05, 05:57 PM
Ted Molczan
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Default See Discovery/ISS in formation after un-docking

Observers at certain latitudes have the opportunity to see Discovery and ISS
in close formation, after they un-dock early Saturday, 2005 Aug 6, at 07:22
UTC (3:22 AM EDT).

Observers between roughly 10 N and 40 N latitude, will have morning
visibility. Observers between roughly 20 S and 55 S latitude, will have
evening visibility. The best passes will occur near the middle of those
ranges; marginal passes will occur near their extremes. Here is some
additional information for U.S. observers:

Saturday August 6

About 09:15 UTC (5:15 AM EDT), Florida will have a low pass, during which
the spacecraft are predicted to be about 1 km apart. Binoculars likely will
be required to resolve them as separate objects.

About 10:50 UTC (5:50 AM CDT), Alabama, Arkansas, Louisiana, Mississippi and
Texas, will have a good to excellent pass. The spacecraft are predicted to
be about 7 km apart, resulting in angular separation of up to 1 deg (if seen
directly overhead).

About 12:21 UTC (5:21 PDT), Arizona and Southern California will have a good
pass. The spacecraft are predicted to be about 29 km apart.

Sunday August 7

On August 7, there will be good to excellent passes of most southern U.S.
states. The spacecraft will be about 250 km apart, or about one half minute
of flight time.

For a quick way to check on visibility where you live, I recommend this page
operated by NASA, which lists major cities around the world:

http://spaceflight1.nasa.gov/realdat...ties/index.cgi

For detailed sky-charts and ground tracks, try Heavens-Above or CalSky:

http://www.heavens-above.com/

http://www.calsky.com/cs.cgi/Satellites/4

NOTE: it is recommended to run your predictions for ISS, because it is not
expected to manoeuvre over the next few days. Just be aware that Discovery
will lead ISS by the distances discussed above.

For those who prefer to make their own computations, I have appended NASA's
predicted orbital elements that take into account Discovery's manoeuvres to
separate from ISS.

Clear skies!
Ted Molczan


Predicted 2-line orbital elements

I have extracted and appended the key elsets for those who wish to evaluate
their prospects to observe the spacecraft in close proximity to one another.

The elsets below were downloaded on 2005 Aug 05 UTC, from the following NASA
site (for shuttle hit the red icon; for ISS, hit the green one):

http://spaceflight1.nasa.gov/realdat...nts/index.html

1. 2005 Aug 06 08:39 - 09:07 UTC (period between separation burn #1 and
burn #2)

Discovery
1 28775U 05026A 05218.38141706 .00016071 00000-0 12697-3 0 9025
2 28775 51.6421 3.8986 0001995 216.2554 143.8473 15.71511439 1719
ISS
1 25544U 98067A 05218.57218742 .00016071 00000-0 12697-3 0 9029
2 25544 51.6445 2.9206 0002067 222.2583 137.8420 15.71515070 23614


2. 2005 Aug 06, 09:07 UTC - Aug 07, 09:08 UTC (after separation burn #2)

Discovery
1 28775U 05026A 05218.38141726 .00016071 00000-0 12697-3 0 9038
2 28775 51.6419 3.8976 0004124 192.2344 167.8719 15.72062763 1713
ISS
1 25544U 98067A 05218.57218742 .00016071 00000-0 12697-3 0 9029
2 25544 51.6445 2.9206 0002067 222.2583 137.8420 15.71515070 23614


3. 2005 Aug 07, 09:09 UTC to Discovery's de-orbit on Aug 08

Discovery
1 28775U 05026A 05219.39849213 .00016071 00000-0 12697-3 0 9047
2 28775 51.6417 358.6892 0004123 193.8333 166.2716 15.72087121 1875
ISS
1 25544U 98067A 05219.58962826 .00016071 00000-0 12697-3 0 9031
2 25544 51.6448 357.7150 0002096 224.7886 135.3107 15.71511262 23772


  #2  
Old August 5th 05, 06:31 PM
Tom Polakis
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Default

Ted Molczan wrote:
Observers at certain latitudes have the opportunity to see Discovery and ISS
in close formation, after they un-dock early Saturday, 2005 Aug 6, at 07:22
UTC (3:22 AM EDT).


About 12:21 UTC (5:21 PDT), Arizona and Southern California will have a good
pass. The spacecraft are predicted to be about 29 km apart.



Ted,

Thanks for the information. I will be watching from Phoenix Saturday
morning. The sun will be only 5 degrees below the horizon, but I think
the satellites will be bright enough. If I did my trig correctly
(distance=512km, separation=29km), the two craft will be separated by
just over 3 degrees when they are at their highest altitude.

Tom

 




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