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### How to obtain UTC of the epoch time in a satellite TLE (two line element)?

I want to convert the epoch time of a TLE to UTC. At this moment I am less interested in explanations and history - I just want to know quantitatively, with certainty, how to convert. I'm confused ...
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### How can I plot a satellite's orbit in 3D from a TLE using Python and Skyfield?

I have obtained a Two Line Element (TLE) of a satellite in Earth orbit from Celestrak at https://celestrak.org/NORAD/elements/ and I would like to use it to calculate an orbit. How can I calculate the ...
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### Why are Tiangong-1's Apogee and Perigee Graphs Wobbly?

The apogee and perigee graph of the Tiangong-1 space station, about to re-enter and break up Real Soon Now, is depicted in this graph (source: Wikipedia): Why are the graphs wobbly? Is it because the ...
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### Is SGP4 propagation necessarily more accurate near the epoch chosen for TLE generation?

This interesting answer includes a quote from Space-Track: From Space-Track.Org FAQ TLEs can contain future epochs. About 20 satellites are categorized as "multi-day objects" because ...
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### Differences between SGP8 and the standard SGP4? Is it ever used in practice?

The Wikipedia article Two Line Element Set says: The SGP4 model was later extended with corrections for deep space objects, creating SDP4, which used the same TLE input data. Over the years a number ...
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### Sun-synchronous satellite orbit propagation

I'm trying to propagate the orbit of a sun-synchronous satellite. The initial data is defined by the TLE. The orbit of the satellite is controlled by the operator ...
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### TLE SGP4 Coordinate Transformations

I am working on developing a user friendly SGP4 orbit propagator in C on a PIC24. I have extensively read Revisiting Spacetrack Report #3 and celestrak - there are a few outstanding questions I have. ...
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### Is the amount of accurate information in a TLE equal to that of a single state vector?

My question is basically regarding whether there is orbital information "lost" when converting from a Two Line Element set (TLE) to a state vector. Given that the following are true: I have a TLE, ...
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### Why are Keplerian elements used in TLEs instead of Cartesian state vectors?

Propagating a state vector seems easier, you just account for the gravity, change the velocity and update the position. It also allows to easily apply perturbations, etc. Additionally, the ...
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### Has a TLE ever been issued for a spacecraft trajectory not bound to Earth orbit?

This excellent answer to the question Why has no TLE been published for the DSCOVR satellite and the Falcon 9 R/B? suggests that to the best of the writer's knowledge TLEs are only issued for ...
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### For any state vector of a satellite at an arbitrary time T1, is there another state vector at a given time T2 that will result in the same orbit?

I recently found the question In a 3D space defined by semimajor axis, eccentricity and inclination, what would be the shape of the space where SDP4 works better than SGP4? and have become interested ...
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### Get dates when a satellite has performed maneuver from historical TLE data (python)?

I have been recently acquainted with orbital mechanics and am trying to do some analysis on the subject. Since I don't have subject matter expertise, I am at a crossroads with trying to decide that ...
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### When calculating the future orbit of an artificial Earth satellite, is the Moon's gravity significant or insignificant?

Imagine a mathematician is plotting the future orbit of a satellite to be launched and put in orbit around the Earth. When they are making their calculation, is the moon so far away and the ...
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### In a 3D space defined by semimajor axis, eccentricity and inclination, what would be the shape of the space where SDP4 works better than SGP4?

@BillGray's answer to Why can't custom-made TLEs for the DSCOVR launch booster in orbit around Earth work with SDP4? is quite interesting and informative; I fail to do it justice by summarizing it as ...
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