How to calculate terminator coordinates/subsolar point

If you want to know the terminator (sun-night boundary) position, pyana.cy1orb.terminator module will help.

>>> from pyana.cy1orb.terminator import terminator
>>> from pyana.util.julday import Julday
>>> pos = terminator(Julday(2009, 1, 29, 0, 0, 0))

Returned value is a list of ndarray.

>>> posme = terminator_asdegrees(Julday(2009, 1, 29, 0, 0, 0))

will return the ndarray with shape of nSample x 3. posme[:, 0] is longitude, posme[:, 1] is latitude and posme[:,2] is height (typically very small number).

For subsolar point, similar interface is implemented.

>>> from pyana.cy1orb.subsolar import subsolar
>>> from pyana.util.julday import Julday
>>> pos = subsolar(Julday(2009, 1, 29, 0, 0, 0))
>>> posme = subsolar(Julday(2009, 1, 29, 0, 0, 0))

Note that the subsolar point is the point, so pos is 3-length ndarray and posme is [longitude, latitude].