# Questions tagged [coordinate-systems]

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### Correct longitude from longitude over 180°

Last week, one of my exercise tasks was about determining the an observer's position on Earth, when in their zenith is a certain star with known right ascension and declination. We were supposed to ...
1 vote
38 views

### Orekit converting to galactic coordinates

I started using OreKit in a 3D star charting app I am writing in JavaFX. I wanted to convert from equatorial to galactic coordinates. I can do it simply by using the transformations, but I wanted to ...
1 vote
43 views

### Equatorial Co-Ordinates of the Solar Barycentre

Does anyone know where the solar barycentre is in the old equatorial (based on Earth's position on midday, 01/01/2000) system? I want to add an ICRS option for a 3d model I'm working on. EDIT: degrees ...
73 views

### How to transform between horizontal and equatorial coordinates?

I want to express the transformation between horizontal (azimuth $A$,elevation/altitude $\varepsilon$) coordinates and equatorial (hourangle $H$/right ascension $\alpha$, declination $\delta$) as a ...
166 views

### Reverse polynomial model for reverse astrometry

I have a polynomial model that can transform pixel X,Y coordinates to standard $\xi, \eta$. This model looks like this: \$\xi/\eta = a_1 + a_2x + a_3y + a_4x^2 + a_5xy + a_6y^2 + a_7x^3 + a_8x^2y+a_9xy^...
133 views

### Angular distance calculation in Equatorial and Galactic coordinates

I calculated the angular distance between the Galactic Center and Andromeda in Equatorial and Galactic coordinates and observed that the distance is calculated differently depending on the coordinate ...
1 vote
51 views

### Transforming radio sources in a T-RECS catalogue from one field to another

I have sources that I extracted from The Tiered Radio Extragalactic Continuum Simulation (T-RECS) catalogue for a deep field. I use these sources to generate a sky model at different fields within a ...