Computing bboxes for STC geometries.

A bbox coming out of this module is a 4-tuple of (ra0, de0, ra1, de1) in ICRS degrees.

(You’re right, this should be part of the dm classes; but it’s enough messy custom code that I found it nicer to break it out).

class, lat1, long2, lat2)[source]

Bases: object

A great circle segment on a sphere. It is assumed that it’s no larger than pi.

Construction is long,lat, long, lat in rad (or use the fromDegrees class method.

Very small (<1e-8 rad, say) segments are not supported. You should probably work in the tangential plane on that kind of scale.

classmethod fromDegrees(long1, lat1, long2, lat2)[source]

returns a sequence of bounding boxes for this great circle segment.

Actually, the sequence contains one box for a segment that does not cross the stitching line, two boxes for those that do.


returns the latitude the great circle is on for a given longitude.

Input and output is in rad.

If the pole is part of the great circle, a constant (but fairly meaningless) value is returned.[source][source]

iterates over the bboxes of the areas within ast.

bboxes are (ra0, de0, ra1, de1) in ICRS degrees., lat1, long2, lat2)[source]

returns the initial heading when going from one spherical position to another along a great circle.

Everything is in rad, angle is counted north over east.[source]*bboxes)[source]

returns a bounding box encompassing all the the bboxes passed in.

No input bbox must cross the stitching line; they must be normalized, i.e., lower left and upper right corners.