.. _emitter-astroobject:

Distant astronomical object (:monosp:`astroobject`)
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.. pluginparameters::

 * - irradiance
   - |spectrum|
   - Spectral irradiance, which corresponds to the amount of spectral power
     per unit area received by a hypothetical surface normal to the specified
     direction.
   - |exposed|, |differentiable|

 * - to_world
   - |transform|
   - Emitter-to-world transformation matrix.
   - |exposed|

 * - direction
   - |vector|
   - Alternative (and exclusive) to `to_world`. Direction in which the emitter
     is visible in world coordinates.

 * - angular_diameter
   - |float|
   - Angular diameter of the object in degrees. (Default: 0.5358)

This emitter plugin implements an environment light source simulating a
distant astronomical object. It radiates a specified power per unit area within
a solid angle specified by the `angular_diameter` parameter.  By default, the
emitter radiates in the direction of the positive Z axis, i.e. :math:`(0, 0, 1)`,
with an angular diameter equal to the average apparent size of the Sun from Earth.