histastro.moon module
Moon functions for HistAstro.
- histastro.moon.compute_lbr(jde, lrTerms, bTerms, debug=False)[source]
Compute the geocentric ecliptic coordinates of the Moon for the equinox of date for the given JDE.
- Parameters:
jde (float) – Julian Day in dynamical time, i.e., corrected for Delta T (days).
lrTerms (float) – Numpy array with ELP82 periodic terms for longitude and distance.
bTerms (float) – Numpy array with ELP82 periodic terms for latitude.
debug (bool) – Produce debug output. Optional, default value = False.
- Returns:
Tuple containing (lon, lat, dist, diam):
lon (float): Geocentric ecliptic longitude of the Moon (rad).
lat (float): Geocentric ecliptic longitude of the Moon (rad).
dist (float): Geocentric distance of the Moon (km).
diam (float): Geocentric apparent diameter of the Moon (rad).
- Return type:
tuple (float,float,float,float)
Notes
A reduced version of the ELP82 theory is used.
The necessary ELP82 terms can be read from file using the function readData().
References
[Chapront-Touze & Chapront, A&A 190, 342 (1988)](https://ui.adsabs.harvard.edu/abs/1988A%26A…190..342C).
- histastro.moon.readData(inFile='data/moonposMeeus.csv')[source]
Return the periodic terms for the ELP82B theory from moonposMeeus.csv.
Two arrays aand return them in two arrays: one for longitude and distance, and one for latitude.
- Parameters:
inFile (str) – Name of the input file, including (relative or absolute) path. Optional, default
value = ‘data/moonposMeeus.csv’.
- Returns:
Tuple containing (lrTerms, bTerms):
lrTerms (float): Numpy array containing six columns with periodic terms for longitude and distance. The first four columns contain arguments for both variables, the last two the coefficients for longitude and distance:
1 (int): Multiplication factor for the mean elongation of the Moon.
2 (int): Multiplication factor for the mean anomaly of the Sun.
3 (int): Multiplication factor for the mean anomaly of the Moon.
4 (int): Multiplication factor for the Moon’s argument of latitude.
5 Coefficient of the sine of the argument, for the longitude (rad).
6 Coefficient of the cosine of the argument, for the distance (km).
bTerms (float): Numpy array containing five columns periodic terms for latitude. The first four columns contain arguments, the last contains the coefficients for latitude:
1 (int): Multiplication factor for the mean elongation of the Moon.
2 (int): Multiplication factor for the mean anomaly of the Sun.
3 (int): Multiplication factor for the mean anomaly of the Moon.
4 (int): Multiplication factor for the Moon’s argument of latitude.
5 Coefficient of the sine of the argument, for the latitude (rad).
- Return type:
tuple (float,float)
References
[Jean Meeus: Astronomical Algorithms, 2nd Ed. (1998)](https://www.willbell.com/math/MC1.HTM), Ch.47.