HTML/JS: Galactic to Equatorial coordinates

Converter

Fromula

To convert from galactic to equatorial coordinates,

\small
\begin{equation}
\sin(\delta) = \sin(\delta_\text{NGP})\sin(b)+ \cos(\delta_\text{NGP})\cos(b)\cos(l_\text{NCP} - l)
\end{equation}

\small
\begin{equation}
\tan(\alpha - \alpha_\text{NGP}) = \frac{\cos(b)\sin(l_\text{NCP} - l)}{\cos(\delta_\text{NGP})\sin(b) - \sin(\delta_\text{NGP})\cos(b)\cos(l_\text{NCP} - l)}
\end{equation}

According to IAU, the values of $l_\text{NCP}$, $\delta_\text{NGP}$, and $\alpha_\text{NGP}$ are $122.9320^\circ$, $27.1284^\circ$, and $192.8595^\circ$ respectively.

Galactic coordinates

1. Independant of the observer’s location and time of observation.
2. Heliocenteric, the galactic plane is the fundamental plane for the galactic coordinate system.
3. Primary direction is towards the center of Milky Way galaxy.
4. It is a right-handed coordinate system, positive towards North and East direction.

Equatorial coordinates

1. Indepdendant of the observer’s location and time of observation.
2. Earth centeric, the equator of Earth is the fundamental plane for the equatorial coordinate system.
3. Primary direction is towards the vernal equinox.
4. It is a right-handed coordinate system, positive towards North and East direction.

See more

For python codes to convert galactic to equatorial coordiantes, see the post “How to interconvert celestial coordinate systems?#Equatorial_Galactic”.

See also, “Equatorial to Galactic coordinate converter”.