Editing Galactic coordinate system (section)

==Conversion between equatorial and galactic coordinates==
An object's location expressed in the [[equatorial coordinate system]] can be transformed into the galactic coordinate system. In these equations, {{math|''α''}} is [[right ascension]], {{math|''δ''}} is [[declination]]. NGP refers to the coordinate values of the north galactic pole and NCP to those of the north celestial pole.<ref>{{cite book |last1=Carroll |first1=Bradley |last2=Ostlie |first2=Dale |title=An Introduction to Modern Astrophysics |year=2007 |publisher=Pearson Addison-Wesley |isbn=978-0805304022 |pages=900–901 |edition=2nd}}</ref>

:<math>
\begin{align}
\sin(b) &= \sin(\delta_\text{NGP})\sin(\delta)+\cos(\delta_\text{NGP})\cos(\delta)\cos(\alpha-\alpha_\text{NGP}) \\
\cos(b) \sin(l_\text{NCP}-l) &= \cos(\delta)\sin(\alpha-\alpha_\text{NGP}) \\
\cos(b) \cos(l_\text{NCP}-l) &= \cos(\delta_\text{NGP}) \sin(\delta) - \sin(\delta_\text{NGP}) \cos(\delta) \cos(\alpha - \alpha_\text{NGP})
\end{align}
</math>

The reverse (galactic to equatorial) can also be accomplished with the following conversion formulas.
:<math>
\begin{align}
\sin (\delta) &= \sin (\delta_\text{NGP}) \sin(b) + \cos (\delta_\text{NGP}) \cos(b) \cos(l_\text{NCP} - l) \\
\cos (\delta) \sin(\alpha - \alpha_\text{NGP}) &= \cos(b) \sin(l_\text{NCP} - l) \\
\cos (\delta) \cos(\alpha - \alpha_\text{NGP}) &= \cos (\delta_\text{NGP}) \sin(b) - \sin(\delta_\text{NGP}) \cos(b) \cos(l_\text{NCP} - l)
\end{align}
</math>

Where:

:<math>\alpha_\text{NGP}=12^h 51.4^m \qquad \delta_\text{NGP}=27.13^{\circ} \qquad l_\text{NCP}=122.93314^{\circ}</math>