3.4. Circle
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## 3.4. Circle #

A spherical circle is an area around a point, where all points inside the circle have a distance less than or equal to the radius of the circle. Use cases are:

- sites on earth having a maximum distance from another site

- round cluster or nebula on sky sphere

- a position with an undirected position error

A circle is specified using a spherical point (`spoint`) and a radius :

    < point , radius >

Valid radius units are `RAD`, `DEG`, and `DMS`. The circle radius must be less than or equal to 90° and cannot be less than zero.

Example 3.7. A circle around the North Pole with a radius of 5°.

    sql> SELECT scircle '< (0d, 90d), 5d >';

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