Questions tagged [eci]

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4
votes
1answer
64 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,...
1
vote
0answers
20 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 ...
4
votes
2answers
100 views

How to find ECI coordinates for a circular orbit

Suppose a satellite is orbiting Earth in a circular orbit, of which I know the inclination $i$, the right ascension of the ascending node $\Omega$, the semi-major axis $a$ (or orbit radius given that ...
3
votes
1answer
168 views

How to solve the two-body problem in the ECI frame through numerical integration?

I need to know how to solve two-body problem by solving a system of first order equation derived from the equation below. $$\ddot{\mathbf{r}} = -\frac{\mu}{r^3}\mathbf{r}$$ How do I go about this, and ...
4
votes
3answers
606 views

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 ...
1
vote
0answers
51 views

J2000 to current ECI transformation matrix

I want to find the transformation matrix that converts an ECI frame at some time 't' (lets say t = 1st January 2020) to J2000 ECI frame (that is ECI frame at noon of 1st January 2000). From what I ...
2
votes
1answer
67 views

Could the orbit of a satellite place it on the z-axis of the ECI coordinate frame (x=y=0)?

It is mostly a hypothetical question; I assume the answer is no, but I am looking for any data to contradict my claim that there are none or at most only one satellite at a time which could ever ...
1
vote
2answers
215 views

Accuracy of direct ECI (Earth-Centered Inertial) to LLA (Longitude, Latitude, Altitude) conversion via sub-satellite point?

The process of converting between ECI and LLA is generally known to be complex, as it involves a intermediate conversion to ECEF (Earth-Centered, Earth-Fixed). This, in turn, involves the ...
3
votes
3answers
466 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 (...
4
votes
1answer
814 views

C/Fortran library for ECI to ECEF conversion

Does anyone know of a good C or fortran library which constructs the rotation matrix to convert from ECI to ECEF components?