# coordinax.astro

```{toctree}
:maxdepth: 1
:hidden:

api.md
spec.md
```

Astronomy-specific reference frames for [coordinax](https://github.com/GalacticDynamics/coordinax).

This package provides astronomical reference frames like ICRS and Galactocentric for use with `coordinax`, enabling transformations between different astronomical coordinate systems.

## Installation

::::{tab-set}

:::{tab-item} pip

```bash
pip install coordinax[astro]
```

:::

:::{tab-item} uv

```bash
uv add coordinax --extra astro
```

:::

::::

## Quick Start

```
import coordinax.main as cx
import coordinax.astro as cxastro
import unxt as u

# Create a position in ICRS frame
pnt = cx.Point.from_({"r": u.Q(10, "kpc"), "theta": u.Q(45, "deg"), "phi": u.Q(30, "deg")})
crd_icrs = cx.Point({"base": pnt}, frame=cxastro.ICRS())

# Transform to Galactocentric frame
crd_gc = crd_icrs.to_frame(cxastro.Galactocentric())
```

## Available Frames

### ICRS

The International Celestial Reference System (ICRS) is the standard celestial reference frame.

```
frame = cxastro.ICRS()
```

### Galactocentric

A reference frame centered on the Galactic center with configurable parameters.

```
frame = cxastro.Galactocentric(
    galcen={"lon": u.Q(266, "deg"), "lat": u.Q(-29, "deg"),
            "distance": u.Q(8.122, "kpc")},
    z_sun=u.Q(20.8, "pc"),
)
```

## Frame Transformations

The package provides frame transformation functions that work with coordinax's coordinate system:

```
# Create a coordinate in one frame
crd_icrs = cx.Point({"base": pnt}, frame=cxastro.ICRS())

# Transform to another frame
crd_gc = crd_icrs.to_frame(cxastro.Galactocentric())
```

## API Reference

See the {doc}`API Reference </packages/coordinax.astro/api>` for complete documentation of all frames and functions.

## License

MIT License. See [LICENSE](../../../LICENSE) for details.