Questions tagged [two-line-elements]
Set of values carefully prepared to be used together with a simplified perturbations model (most often SGP4) to predict satellite positions with a moderate level of accuracy for times near the epoch contained within the TLE.
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Distance between a satellite and an orbit
I would like to compute the distance between a satellite and a specified orbit. For instance, for an orbit at 897 km altitude, 0 degree eccentricity, 99 degree inclination, and RAAN of 0 degrees on ...
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TLE along track error to miss a contact opportunity in UHF
Update: (following @GregMiller's comment):
Lets suppose a spacecraft has performed a boost and not all ground stations received the update, lets suppose the difference between the pre and post ...
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How do SDP4's "Deep space" corrections to SGP4 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 ...
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How to make my generated two line elements more accurate?
I am using Orekit to generate TLEs. I am then propagating those elements out and comparing it to the ephemeris used to generate them. This results in a residual error in excess of 20 km. I am not ...
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Use ECI cordinates to plot orbit in three.js
I am using satellite.js to get ECI coordinates from TLE data. Now my first question is can ECI coordinates be used to plot satellite orbit as shown here.
If yes then how can i do that in three.js?
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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 ...
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What would the TLE data (Mean Motion, Eccentricity, Inclination, RAAN, Argument of Pericenter) of GEO and PO be like?
I am currently making a satellite tracker app for android. I want to test my orbit propagation algorithm and I want to make some made-up basic orbits, so I need to know how their TLE would be. I want ...
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How (the heck) are military satellites with (apparently) classified TLEs still showing up on sat map websites?
As I first noted in this comment I couldn't get TLEs for the recently launched OFEQ-11 spy satellites from space-track.com. When I looked at Search Resuls: OFEQ 11 Satellite details 2016-056A NORAD ...
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Plot ellipse using elements from TLE
I am trying to draw an ellipse as satellite orbit in three.js, It has an EllipseCurve class which takes these inputs and draws an ellipse around center.
EllipseCurve( aX : Float, aY : Float, xRadius : ...
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Is there a python library to determine the position of a satellite at a given time from TLE data excluding the Satellite catalog number?
Or perhaps some simple code or formula that achieves this. I've used pyephem but it requires a Satellite catalog number.
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Issue with propagating TLE sets using SGP4
I am trying to make some analysis on conjunction events using the TLEs available from Celestrak's SOCRATES page. Take for example the following predicted event:
Here's my issue: when I try to ...
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How to Update the Epoch in a Fake TLE While Maintaining Relative Position?
I've been trying to compare before & after results for some updated algorithms in an application. Basically, I want to be able to start and run the test at any arbitrary Epoch with the satellite ...
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What are common problems when downloading and processing TLE data from Space-Track?
A few of my colleagues and I are trying to download the latest version of the TLE Catalogue from space-track. We've been using the Space-Track TLE Retriever 3 program and we've been able to download ...
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Are the TLE of a satellite computed with the ECI or ECEF?
I want to compute the distance of a certain satellite, given the TLE, to a ground station in the earth. I have the latitude, longitude and altitude of the ground station. But I don't know if the TLEs ...
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satellite ground track calculation
I'm trying to calculate the ground track of an earth-orbiting satellite (Longitude, latitude)
I found this handy way on the documentation but it's good when trying to find a single point what if I'm ...
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How to propagate the orbit of a satellite analytically using Lagrange planetary equations/VOPs and compare them with numerically propagated solution?
I have propagated the orbit of a satellite from TLE elements numerically using RK4 method. But I'm bit confused when it comes to the propagation of satellite orbits using analytical approach. From ...
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How might an "imminent Starlink reentry in your area" alerting script work?
The video below Space debris over Puerto Rico (2/7/2022) SAC seems likely to show one or more reentering Starlink satellites from the 40 "Starlost" lost to atmospheric heating due to a ...
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calculating satellite position and velocity from TLE
I'm trying to calculate satellite orbit from the TLE set
at first, I used several libraries including SGP4, Skyfiled to get the initial position and velocity of the satellite at the epoch time
I know ...
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satellite orbit propagation from initial position and velocity [duplicate]
I'm trying to get the satellite orbit at a certain time given the initial position and velocity (SGP4) say I have a TLE file that is taken in epoch:(2022-01-05 11:25:15.578) and I need to get the ...
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How do I know the exact TLE of my satellite after its deployment?
The satellites are launched in a cluster. How can I validate the TLE of my satellite in the early days following deployment, because there are more than two satellites that are close to each other and ...
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Why can n2yo somehow interpret this TLE but Skyfield can't? Why does it return nans and zeros for position?
@Rafa pointed out that there is at least one officially released TLE for the JWST mission after it left Earth orbit, and here's the latest one at n2yo.com:
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Does the James Webb Telescope have a Two Line Element set?
How do you track the position of the James Webb telescope? Does it have its own TLE, or...?
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What caused the ISS Two Line Element Day of Year problem beginning 12-24-2019?
Does anyone know happened at NORAD or NASA or wherever the published TLEs originate, that caused the ISS TLE wonkiness during the last week of 2019? It did not happen in 2018. What happened? The ...
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Failing at getting apogee and perigee from TLE
At Celestrak, the current orbit for ISS is currently listed as 423x417 km, but if I'm getting the TLE data from Celestrak and use orb.get_lonlatalt(now) from ...
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Suppose I wanted to compare TLEs to actual LEO satellite positions, what data is available? From which may it be easiest to extract X, Y, Z, T points?
Under @RyanC's answer to How can I plot satellite's trajectory from three different TLEs to detect any deviation on path with time? I wrote:
I think that SGP4 + TLEs is so popular because the TLEs ...
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TLE and RINEX gps differences
I have TLE and RINEX navigation file for GPS satellite PRN 20, for 01.04.17r. 19:56:56 and 20:00:00 respectively. See also The Receiver Independent Exchange Format Version 3.03.
It seems that the ...
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Covariance matrix of a satellite position
In order to estimate the probability of collision with space debris, the covariance matrix of the primary and secondary objects should be calculated (JSPoC paper). I'm going to calculate the matrix ...
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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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PRN number in TLE files are the same in RINEX files? (in GPS constellation)
I want to compare the position calculated with Pyephem and TLE files, with RINEX files and GPSTK library in a specific date and time, but I have not the certainly if the name of the satellite "...
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How to construct $B^*$ drag term in TLE?
Is it possible to calculate $B^*$ term in TLE data using only a few or more velocity and position vectors for a satellite?
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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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How can I plot satellite's trajectory from three different TLEs to detect any deviation on path with time?
I have obtained TLE information of a satellite from space-track.org for three different times. I am trying to study any deviation of the satellite trajectory from its usual path. Here I am comparing ...
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Where is this LightSail-2 trajectory data coming from? Is there more than TLEs available to the public?
This tweet shows high granularity data for LightSail-2's perigee and apogee, showing that while the apogee-raising strategy is working nicely, currently atmospheric drag is taking its toll and the ...
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Given the measured positions of an object, how to retrieve its latest TLE?
I'm working on a simulation space project, in which I simulate the positions of all the Low Earth Orbit objects at any time.
For the moment I have a 3LE database of LEO objects, and each time a ground ...
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Where to look for historical or reconstructed orbit data for early NASA missions - Mercury-Atlas 6 for example
After reading this answer to How many earth stations had astronauts on-site during John Glenn's orbit in Friendship-7? I decided that for my own use I'd like to plot the orbit of Mercury-Atlas 6, the ...
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Calculating Which Satellite Passes are Visible - Need help
I am a beginner Python programmer. I am trying to get the code in the article "Calculating which satellites are visible" to function without success. My plan is to identify satellites that ...
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What was the first proper Two Line Element to be generated?
In this question I describe looking for a TLE for Mercury-Atlas 6, the spacecraft piloted by John Glenn on February 20, 1962. I'll post here the relevant information:
While the TLE catalog available ...
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Is there an API for accessing old TLEs of non-historic objects?
There are various APIs online for accessing TLEs for a satellite object from CelesTrak. However, the APIs retrieved are usually the most recent ones generated.
There are also a lesser number of APIs ...
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How to generate TLEs based on a set of observation points (location, azimuth, elevation... no range)
I'm interested in generating a "corrected TLE1" based on observation data. I would have observed azimuth and elevation, site location, and time. All of those data fields are observed with ...
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How do cubesat owners first find out their cubesat's initial trajectory? How do they point antennas at it before official TLEs start to appear?
When cubesats are first deployed it can sometimes take several days before they start appearing in official TLE distributions, and even then if many were deployed it may take a lot more work to decide ...
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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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Textbook or scholarly discussion of equations used by the SDP4 part of SGP4 TLE propagators beyond Space Track Report #1?
(the famous) Space Tract Report #3 discussed at length in Dr. T.S. Kelso's Revisiting Spacetrack Report #3, AIAA 2006-6753 Describes the "deep space" corrections to the original SGP4 known ...
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Did Tianzhou-2 have a TLE before docking with Tianhe 8 hours after launch? Which is the 2nd stage rocket body and roughly how soon will it reenter?
Clicking on https://celestrak.org/NORAD/elements/stations.txt I get
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Where can i find ELSETS with Co-Variances?
For Special Permutations (I'm a novice), an ELSET with covariance is more accurate than without covariance. A TLE doesn't have room for any covariance. However, I can't seem to find a catalog that ...
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Why can't custom-made TLEs for the DSCOVR launch booster in orbit around Earth work with SDP4?
This fascinating answer to Why has no TLE been published for the DSCOVR satellite and the Falcon 9 R/B? presents links to custom-made TLEs for the Falcon 9 rocket body that put DSCOVR into orbit, and ...
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Is Vallado's Revisiting Spacetrack Report #3 still relevant today?
The title pretty much sums it up. I am reading David A. Vallado's Revisiting Spacetrack Report #3, which was published in 2006 and includes source code for the SGP model series. I was wondering, is ...
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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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What is the "+" symbol for the drag term encoded in a TLE?
I have two TLE, the drag term for the first TLE is -26868-1, which I suppose equals to -0.026868. But on the second TLE, we have ...
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What is/was legacy TLE ephemeris type 2? (TLE, line 1, column 63)
Wikipedia's Two-Line Element Set entry for line 1, column 63 (1.12) says:
Ephemeris type (internal use only - always zero in distributed TLE data)13
13Celestrak Frequently Asked Questions: Two-Line ...
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Determine orbit type from TLE
I was wondering if, and how, one can tell from the values in a TLE whether an orbit is LEO, MEO, HEO, or GEO. I'd like to do this in code eventually, so any formulas or threshold values would be much ...
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