%YAML 1.1
---
$schema: "http://stsci.edu/schemas/yaml-schema/draft-01"
id: "http://stsci.edu/schemas/asdf/transform/sanson_flamsteed-1.4.0"
title: |
  The Sanson-Flamsteed projection.

description: |
  Corresponds to the `SFL` projection in the FITS WCS standard.

  The pixel-to-sky transformation is defined as:

  $$\phi &= \frac{x}{\cos y} \\
    \theta &= y$$

  And the sky-to-pixel transformation is defined as:

  $$x &= \phi \cos \theta \\
    y &= \theta$$

  Invertibility: All ASDF tools are required to provide the inverse of
  this transform.

allOf:
  - $ref: "pseudocylindrical-1.4.0"
...
