Author Topic: One way to download LEO's from Space-Track  (Read 19 times)

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Offline Jimmy Andrews

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One way to download LEO's from Space-Track
« on: September 13, 2018, 08:40:25 PM »
I saw Darwin's message about tracking fast moving LEO's (Low Earth Objects)
 to practice tracking that fast moving ISS.

I've been trying to to understand Space-Track's API URL parameters.
Not very easy for me but I have something right or wrong and seems to work.

Login in to Space-Track

https://www.space-track.org/auth/login

Double click the following link for a list of 256 LEO's
Or select, copy and paste into browser for a list of 256 LEO's

Ansi codes for special characters in url
%3E   greater than (>)
%3C less than (<)
%20 space ( )
If you put this url in a batch file, you may need to add an extra % to each. (%%3E, %%3C, %%20)

One of these faster satellites has a horizon to horizon duration of 3 minutes (must be a highly elliptical orbit).
The ISS takes 10 minutes from horizon to horizon.  Most of these LEO's are 8 to 12 minutes duration.


https://www.space-track.org/basicspacedata/query/class/tle_latest/ORDINAL/1/PERIOD/80--100/EPOCH/%3Enow-7/predicates/object_name,tle_line1,tle_line2/orderby/MEAN_MOTION%20desc/limit/256/format/3le/emptyresult/show


Copy and paste your results into a file.  I call my file leo.txt  Remember where it's located.

Start SatelliteTracker
Click Open tle
Find and select your tle file (leo.txt)

Click window at right of Refresh List to view satellites

Below Open TLE is Batch Predict

Click Batch Predict

Select start day and time
For the next 300 minutes (5 hours)
Pass duration greater than 8 minutes
Max Elevation greater than 20 degrees

I place a check mark beside Low Mod and High Altitude

Click Calculate
Wait for Calculate 1-256 of 256 objects to finish
Click Add to View Plan
Click Close

Click View Plan to see what's coming up when and where

Sometimes I click ''Remove All'' and start a new Batch Predict

If you want to track one of the visible satellites,
Select that line
click ''Select Object''

Information for that satellite will display in left panel.

Click Predict Pass to see when it's visible and Max Elevation at your location.
Pass duration greater than 2 minutes
Check mark beside Exclude Daytime passes
May need to close and reopen Predict Pass to re-read any changes if you changed something.
You need to select a line before clicking World Map, Sky Map or add to view plan

Click Next 24 Hours to see if it's viewable tomorrow or the day after.
Click close when finished

Click ''Start Tracking''
Center object with Timing Offset and Alignment Adjustment buttons

Start with a low power eyepiece.
Increase eyepiece power at your own pace.


-----------------------------------------------------
Optional:
Explanation of some of the API url parameters.

Not sure about first part
https://www.space-track.org/basicspacedata/query/class/

List last 5 tle's of object
tle_latest/

Adding /ORDINAL/1/ to the URL will show only the most recent TLE for each object.
ORDINAL/1/

Period of 80 to 100 minutes the ISS is around 93 minutes
PERIOD/80--100/

EPOCH less than 7 days old
EPOCH/>now-7/ or with Ansi character EPOCH/%3Enow-7/

Remove 0 from beginning of line 0
predicates/object_name,tle_line1,tle_line2/

Order by revolutions per day descending (Fastest moving to Slowest)
orderby/MEAN_MOTION desc/ or with Ansi character orderby/MEAN_MOTION%20desc/

limit to 256 tle's
limit/256/

3 line tle
format/3le/

If no results are found, display ''NO RESULTS RETURNED''
emptyresult/show

Jimmy
When someone says That's Impossible,
 that means they don't know how to do it and
 they don't think anyone else can figure out how to do it.
Possible can be done today, Impossible takes a little longer.