irfpy.cy1orb.terminator

A function to get a terminator in ME frame.

The terminator, the day-night boundary of the planet, is calculated for Moon case. In theory, the Moon has a different polar radius than the equator radius, but for the first trial, the Moon is assumed to be a sphere.

The terminator is simply described in LSE frame: x=0, y=Rm cos(t), z=Rm sin(t). Here Rm is the radius of the Moon, and t is the angle ranging from 0 to 2pi. x,y, and z are functions of the parameter of t.

This coordinates are converted to in ME frame: X,Y,Z by lse2me() method.

irfpy.cy1orb.terminator.terminator(jd, nSample=361)[source]

Get list of terminator coordinates (x,y,z) in ME frame.

Parameters

  • jd – Julian day or the time in datetime.datetime instance.

  • nSample – Number of samples.

Returns

The terminator position vector in the ME frame.

Return type

List of numpy.array.

>>> t0 = datetime.datetime(2009, 3, 10, 0, 0, 0)
>>> tpos = terminator(t0)
>>> print(len(tpos))
361
>>> print(tpos[0].shape)
(3,)
>>> print(tpos[150])   # May change if DB changes.
[  450.13942892 -1456.29471099   834.99925307]
irfpy.cy1orb.terminator.terminator_asdegrees(jd, nSample=361)[source]

Return the array of the coordinate system, (longitude, latitude, height).

Parameters

  • jd – Julian day or the time in datetime.datetime instance.

  • nSample – Number of samples.

Returns

np.array. Shape with [nSample, 3]. Longitude ranges -180 to 180. Latitude ranges -90 to 90. Height should be almost zero.

>>> t0 = datetime.datetime(2009, 3, 10, 0, 0, 0)
>>> tpos = terminator_asdegrees(t0)
>>> print(tpos.shape)
(361, 3)
>>> print(tpos[150])
[-7.28236664e+01  2.87139399e+01 -1.31371162e-04]