Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [sgp4]

The tag has no usage guidance.

1
vote
2answers
119 views

How to correctly make a fake, counter-propagating TLE?

In this answer I have said: Do not make FAKE TLEs! I would now like to make a fake TLE. Specifically I'd like to generate a counter-propagating "twin" of an orbit by flipping inclination by 180° ...
3
votes
0answers
67 views

SGP4: the accumulation of error in radial, in-track and cross-track

I'm propagating the trajectories of 2 LEO satellites (altitude 700 km) in 7 days. Calculating the radial, in-track and cross-track distances to determine the risk of collision. JSPoC states that 0.5 ...
2
votes
0answers
130 views

TLE/SGP4 state vector accuracy assessment

I’m using the Planet Labs state vectors downloadable from http://ephemerides.planet-labs.com/planet.states or http://ephemerides.planet-labs.com/planet_YYYYMMDD.states to assess the TLEs/SGP4 accuracy ...
3
votes
0answers
233 views

Why did the Chinese put the Tiangong-2 so high?

The most obvious answer is that they don’t want to deorbit the station shortly, but why? Some calculations with the TLEs and SGP4 show the following Tiangong-2 / ISS close encounters: ...
3
votes
2answers
105 views

Onboard propagator in satellites SGP or J2

The Earth orbit propagator SGP4 (simplified general perturbation) was developed by NORAD to allow users to generate short-term prediction of satellite positions using two line element sets (TLEs) ...
3
votes
2answers
178 views

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" ...
1
vote
0answers
45 views

Calculating t(E)

The mean radius vector of an elliptic orbit is equivalent to the semi-major axis. If I sample the radius vector of an unperturbed elliptic orbit as a function of the eccentric anomaly with at a ...
2
votes
1answer
166 views

SGP4 gravity model accuracy

From a simulation, I obtain the instantaneous radius vector of the SFERA 2 satellite. If I compare that radius vector with the one obtained from the SGP4 propagator, I get very big differences. The ...
1
vote
1answer
76 views

Converting TLEs into the input data for SGP4

At face value this seems like a trivial question the TLE's are the input to SGP4, but my question is a little more specific. Given a TLE, the values are in specific units (eg. argument of perigee is ...
5
votes
1answer
443 views

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....
4
votes
0answers
119 views

How to calculate a satellite LTAN on the basis of Cartesian coordinates in GCRS frame?

I have calculated the Cartesian coordinates of a satellite in GCRS frame using Skyfield package in python. Propagating the sun-synchronius orbit, I want to analyse the change in its LTAN. How could I ...
0
votes
2answers
916 views

How to generate TLE file?

Subsequently to this answer: What is the way of generation of TLE file for a satellite? How to deal with BSTAR drag term, mean orbital elements, etc.? The generated TLE will be used as the input for ...
4
votes
3answers
661 views

SGP4 TEME frame to J2000 conversion

I've got familiar with the SGP4 model. The problem which I faced is that, the results are in TEME frame. How to convert the TEME to J2000? Would be glad also, if you suggest a method in ...
1
vote
1answer
249 views

SGP4: propagation initialization by state vector

I'm using the SGP4 model to propagate the orbit, initialized by TLE from celestrak.com ...
3
votes
0answers
269 views

“Deep space” corrections in SGP4; how does it account for the Sun's and Moon's gravity?

The Simplified Perturbations model SGP4 is used to calculate Earth satellite state vectors (position and velocity) using standard ephemeris data encoded as TLEs (Two Line Elements). According to ...