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Questions tagged [skyfield]

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4
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0answers
121 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 ...
2
votes
3answers
284 views

How to calculate cone angle between two satellites given their look angles?

I have the azimuth, elevation and distance of 2 satellites relative to a ground station, defined by latitude and longitude, as I've discussed in my previous question. I'm using the satellites' TLEs ...
4
votes
1answer
350 views

What is the difference between GCRS and J2000 frames?

What is the difference between GCRS and J2000 frames? Which is commonly used worldwide in satellite communications? I've read a statement here, that ...
6
votes
2answers
2k views

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://www.celestrak.com/NORAD/elements/ and I would like to use it to calculate an orbit. How can I ...
5
votes
0answers
211 views

What exactly is the interaction that blocked Juno's data downlink near solar conjunction?

According to Space.com's article Juno Phones Home: Jupiter Probe Reconnects with Earth After 8th Flyby, Juno's recent close flyby of Jupiter and data collection happened while Jupiter was too close to ...
6
votes
1answer
215 views

Does it even make sense to talk about Mercury's triangular libration points (L4, L5)?

The recent question How much radiation shielding would be required for a habitat at Mercury–Sun L5? got me thinking. There are a large number of disadvantages and challenges to building or putting a ...
1
vote
1answer
212 views

Ephemeris for lunar body-centered body-fixed coordinates?

I'm going to try to do a modest simulation of the Moon's nutation as seen from the Earth (geocenter), similar to the technical one's I've shown in this question. I'll do it in Python and render it in ...
49
votes
3answers
10k views

Is 75 meters an exceptionally close distance for two satellites to pass at >6,000 m/s?

While researching for this question I ran across something called Celestrak Socrates. I requested the ten closest predicted approaches, and saw distances of closest approach of the order of 100 ...
1
vote
0answers
688 views

Better way to get approximate ground track for a satellite using Skyfield?

I wanted to make a quick ground-track plot, so I used the Python package Skyfield to propagate a TLE and return Earth-Centered Inertial coordinates. Then I created a ...
4
votes
1answer
224 views

JPL Horizons original reference orbit data for Juno - how to retrieve now that it's been updated?

Because of the slow helium valve responses, Juno was not instructed to execute the large delta-v maneuver to drop from the ~53 day orbit to the ~14 day orbit originally scheduled for 2016-Oct-19. I'd ...
3
votes
1answer
218 views

Was the time of Schiaparelli's landing chosen specifically so the Giant Meter Wave Radiotelescope could listen?

The ESA blog post Listening to an Alien Landing describes the plan to monitor a UHF beacon transmitted by Schiaparelli during it's upcoming descent and landing on Mars (2016-10-19 about 14:45 UT). The ...
6
votes
1answer
251 views

Need help getting the true ICRF coordinates of SOHO using Horizons

In this answer I calculated the approximate angular separation between Mercury and the Sun as seen by the SOHO satellite using Skyfield's method of ...
5
votes
1answer
239 views

How to (correctly) rotate this data so the Ecliptic is in the XY plane?

When plotting orbits using the Python package Skyfield, the coordinates are barycentric ICRS. This puts the center of mass of the solar system at the origin, but the $\hat{z}$ axis is tilted about 23° ...
5
votes
3answers
452 views

Asteroid 2013 TX68 March 5, 2016 close approach, and calculating with Skyfield

This NASA webpage describes the close approach of asteroid 2013 TX68 on March 5, 2016 and shows a probability distribution of the point of closest approach based on the only data available at this ...
9
votes
4answers
6k views

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 ...
4
votes
2answers
1k views

Time, UTC, Julian Date, TLE epoch - how are they related quantitatively?

I am trying to understand the relationship (quantitatively) between JulianDate, UTC, and the epoch of Two Line Elements. It's a deep subject, especially if you include relativity, and a long subject - ...
8
votes
1answer
1k views

How to get earth-centered, earth-fixed coordinates from Skyfield?

I recently started using Skyfield (python) to find (x, y, z) coordinates of things in space. Now I'd like to transform between Earth-Centered, Earth-Fixed (rotating) and Earth-Centered Inertial (non-...