Introducing TLE from Proxy software

From: Marco Langbroek via Seesat-l <>
Date: Wed, 15 Nov 2017 14:53:19 +0100
Dear all,

When a new object is to be launched (whether classified or not), often we want
to have an advance idea of its first few orbits.

I have written a small piece of software called "TLE from Proxy", which can do
that for objects that are part of a series of earlier similar launches - e.g.
SpaceX Dragon launches to the ISS. An earlier similar launch then acts as a
proxy for the new launch.

TLE from Proxy can be downloaded through my website:

A screenshot is here:

TLE from Proxy works as follows, in a few easy steps:

1) Get a TLE from an earlier similar launch. This is the proxy TLE.

For example, if you want to predict the first orbit for a new SpaceX DRAGON
launch to the ISS, get a TLE from Space-Track for the first revolution of a
previous DRAGON launch.

Note that it has to be a launch from the same launch site into the same azimuth,
with a similar launch to orbit profile: and if you want a tle estimate for the
first orbit, your proxy TLE also has to be from the first orbit of that launch too.

2) Simply copy and paste line 1 and line 2 of the proxy TLE into the input
   window in TLE from Proxy.

3) Fill in the date and time (in UT) of that particular launch (you can
   often find this information via e.g. Wikipedia).

4) Fill in the expected date and time of the new launch.

5) Now press the button, and a TLE will be generated.

If you generate multiple TLE's for various different assumed launch times, they
will be added below each other in the output box, and the fake SSC number will
auto-increment. Output can be saved to a .txt file, or simply copy-pasted.

TLE from Proxy is based on the method described by Ted Molczan in this Seesat-L
post from June 2002:

Basically, it takes the proxy elset and adjusts the epoch and RAAN value,
keeping all else equal.

The software works under Windows using the .NET framework.


- Marco

Dr Marco Langbroek  -  SatTrackCam Leiden, the Netherlands.

Cospar 4353 (Leiden):     52.15412 N, 4.49081 E (WGS84), +0 m ASL
Cospar 4355 (Cronesteyn): 52.13878 N, 4.49937 E (WGS84), -2 m ASL
Station (b)log:
Twitter: _at_Marco_Langbroek

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