# Questions tagged [ecef]

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### Are ECI and ECEF Frames, and Do They Belong to the Geocentric Equatorial Coordinate Systems?

I'm completely confused about the difference between geocentric equatorial coordinate systems, ECI, and ECEF. David Vallado, in his book 'Fundamentals of Astrodynamics and Applications,' mentions that ...
• 53
195 views

### Why do ~GEO sats seem to cluster around the top portion and bottom portion of the belt, 180 degrees apart?

I made a 3D tle model from https://www.space-track.org/ API. I drew a dashed blue line to show the really "geo" orbits that hardly move with time (ECEF). Then there are a bunch of sats that ...
• 31
1 vote
66 views

### Why ECEF does not coincide with ECI on January 1, 2000 at 12.00? [duplicate]

I assumed that ECEF frame coincides with ECI frame on January 1, 2000 at 12.00. To see that, on MATLAB, I used the dcmeci2ecef() function as: ...
582 views

### Where do I find ECEF coordinates of a satellite?

I am taking a university course named 'satellite navigation' as a part of my master degree in aerospace engineering. For the exam we are required to elaborate the coordinates of a LEO satellite (it ...
• 51
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### Transformation ECI to ECEF acceleration and forces

I know that for velocity conversions between ECI and ECEF there is an $\omega \times r_{ECI}$ term, such that the overall transformation is $v_{ECEF}=v_{ECI}-\omega \times r_{ECI}$. In my belief ...
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746 views

### In which direction does the x axis of the ECI at 1.1.2000 at 12:00 (J2000) go and where is the 0 deg meridian?

I am currently getting a bit lost in reference frames and coordinate systems. From my point of view, I am currently in the ICRS frame. I know that the ECI from my point is only moving but not rotating,...
• 450
3k views

### Converting J2000 to ECEF?

Say I get the orbital elements for the ISS from JPL Horizons. Say that data is expressed in J2000, an inertial frame. I want to express it in ECEF. This is a simple rotation transform. All I need is ...
812 views

### Is it posible to convert JPL Horizons Vectors to ECEF?

I'm needing to accurately find the sun and moon position in ECEF and I'm wanting to make use of JPL's Horisons VECTORS to do this. What data should I export from the web interface and how should I ...
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1 vote
41 views

### Calculating angular deviation from LEO magnetic field

The situation I need to calculate pointing errors for a satellite that points along Earth's magnetic field. The satellite's position and orientation are given to me w.r.t ECI J2000. The orientation is ...
1 vote
429 views

### Earth magnetic field vector in ECEF

I've this problem... I want to express the earth magnetic field vector in ECEF reference frame. As now I've just found some models for computing these values related to the earth magnetic field: D: ...
• 11
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### Are ECI and ECEF both frames and/or coordinate systems? Is there a difference?

I don't know really know the difference between a frame and a coordinate system. I'd proposed ECEF and ECI tags, do we need them? Frames seems to be the standard in meta but there is concern so any ...
• 149k
2k views

### Is this commonly attributed ECI (Earth-Centered Inertial) to ECEF (Earth-Centered Earth-Fixed) transformation accurate?

As noted in this previous Stack Exchange question, and many others like it, the transformation from ECI to ECEF (or vice versa) is not a simple process, requiring several steps and considerations (...
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