%YAML 1.1
---
$schema: "http://stsci.edu/schemas/yaml-schema/draft-01"
id: "http://stsci.edu/schemas/gwcs/fitswcs_imaging-1.0.0"

title: FITS WCS Imaging Transform

description: |
  This transform represents a FITS WCS standard Imaging transform.
  It is defined by the typical FITS WCS parameters (CRPIX, CRVAL, CDELT, PC
  and projection) and implemented using astropy.modeling transforms. Unlike
  the FITS implementation inputs and CRPIX are 0-indexed.


allOf:
  - $ref:  "http://stsci.edu/schemas/asdf/transform/transform-1.4.0"
  - object:
    properties:
      crpix:
        title: CRPIX
        description: |
          Pixel coordinate of the reference point, 0-indexed.
        tag: "tag:stsci.edu:asdf/core/ndarray-1.*"
        ndim: 1
        datatype: float64
        shape: [2]
      crval:
        title: CRVAL
        description: |
          Celestial longitude and latitude of the fiducial point (in degrees).
        tag: "tag:stsci.edu:asdf/core/ndarray-1.*"
        ndim: 1
        datatype: float64
        shape: [2]
      cdelt:
        title: CDELT
        description: |
          Coordinate scales.
        tag: "tag:stsci.edu:asdf/core/ndarray-1.*"
        ndim: 1
        datatype: float64
        shape: [2]
      pc:
        title: PC matrix
        description: |
          Linear transformation matrix.
        tag: "tag:stsci.edu:asdf/core/ndarray-1.*"
        ndim: 2
        datatype: float64
        shape: [2, 2]
      projection:
        title: Celestial sphere projection
        description: |
          An instance of one of the classes in astropy.modeling.projections.
        anyOf:
          - $ref: "http://stsci.edu/schemas/asdf/transform/zenithal-1.4.0"
          - $ref: "http://stsci.edu/schemas/asdf/transform/conic-1.5.0"
          - $ref: "http://stsci.edu/schemas/asdf/transform/quadcube-1.4.0"
          - $ref: "http://stsci.edu/schemas/asdf/transform/pseudoconic-1.4.0"
          - $ref: "http://stsci.edu/schemas/asdf/transform/pseudocylindrical-1.4.0"
          - $ref: "http://stsci.edu/schemas/asdf/transform/cylindrical-1.4.0"

    required: [crpix, crval, cdelt, pc, projection]
...
