# Satellite Right Acension and Declination Calculations

• isi
In summary, The conversation is about someone wanting to calculate the RA/DEC of a satellite from TLE data and asking for help on where to find the necessary calculations. Others suggest using heavens-above.com or reading about orbital elements, but the original person wants to do the calculations themselves. Another person mentions a paper from NORAD that describes different algorithms for propagating the state.
isi
Hi Everyone...

I really want to be able to calculate the RA/DEC of a Satellite from TLE data. For example, the International Space Station (ISS)

Can anyone help to point me in the direction of where to find the claculations I need to perform this conversion from TLE data to RA/DEC?

I would really appreciate any responses to help me solve this conversion calculation!

Many Thanks

I'm not sure how to do it, but would you rather just have the positions given to you? You can get alt-az positions from heavens-above.com

May thanks for the reply.. but no I wish to calculate it! :)
heavens above is good and everything but it gives me no understanding :(
Anyone able to help with the calculation from TLE data to RA/dEC?

isi,

You will first need to propagate the two or three line elements from the epoch time to the time in question. This is the hard part. Once you have accomplished that, the computation of right ascension and declination is fairly easy.

A paper from NORAD (http://celestrak.com/NORAD/documentation/spacetrk.pdf" ) describes several algorithms of various fidelity that you can use to propagate the state.

Last edited by a moderator:

## 1. What is Right Ascension and Declination?

Right Ascension and Declination are coordinates used to locate objects in the sky. Right Ascension is measured in terms of hours, minutes, and seconds, while Declination is measured in degrees, arcminutes, and arcseconds.

## 2. How are Right Ascension and Declination calculated?

Right Ascension is calculated based on the Earth's rotation and the position of the object relative to the Earth's equator. Declination is calculated based on the object's position relative to the Earth's celestial equator. Both coordinates are determined using mathematical formulas and astronomical data.

## 3. Why are Right Ascension and Declination important?

Right Ascension and Declination are important for accurately locating celestial objects in the sky. They are used in astronomy and satellite tracking to determine the position of objects and to plan observations and experiments.

## 4. How do changes in the Earth's rotation affect Right Ascension and Declination?

Changes in the Earth's rotation, such as precession and nutation, can cause small shifts in the values of Right Ascension and Declination. These changes must be taken into account for precise calculations and observations.

## 5. How do I convert Right Ascension and Declination to other coordinate systems?

Right Ascension and Declination can be converted to other coordinate systems, such as equatorial or ecliptic coordinates, using conversion formulas and software programs. It is important to understand the differences between these coordinate systems and how they relate to each other in order to accurately convert coordinates.

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