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# Sky2Pix_HammerAitoff

class astropy.modeling.projections.Sky2Pix_HammerAitoff(*args, **kwargs)

  Bases: `Sky2PixProjection`, `PseudoCylindrical`

  Hammer-Aitoff projection - sky to pixel.

  Corresponds to the `AIT` projection in FITS WCS.

  \[\begin{split}x &= 2 \gamma \cos \theta \sin \frac{\phi}{2} \\ y &= \gamma \sin \theta\end{split}\]

  where:

  \[\gamma = \frac{180^\circ}{\pi} \sqrt{\frac{2}{1 + \cos \theta \cos(\phi / 2)}}\]