./
eve_sun_almanac.pro
Routines
result = eve_sun_almanac_mlmod(x, y)
Matlab modulus function.
result = eve_sun_almanac(JD [, R=R] [, B0=B0] [, alpha=alpha] [, delta=delta] [, lambda=lambda] [, alt_r=alt_r])
Low precision formulas for the Sun's coordinates and the equation of timeFrom 2002 Astronomical Almanac, p.
Routine details
top source eve_sun_almanac_mlmodprivate
result = eve_sun_almanac_mlmod(x, y)
Matlab modulus function. Handles negative numbers the "proper" way, the same way that matlab does. For instance, if you have 8 mod 5, the answer is 3, and all modulus functions do it this way. On the other hand, implementations disagree on -3 mod 5. If the denominator is positive, the sensible thing is to have the result be between 0 and almost the denominator. However, most implementations including IDL mod will give a negative result.
Return value
Returns x mod y, and result shares sign of y. Referred to as "floored division" by Knuth.
Parameters
- x in required
numerator
- y in required
denominator
top source eve_sun_almanac
result = eve_sun_almanac(JD [, R=R] [, B0=B0] [, alpha=alpha] [, delta=delta] [, lambda=lambda] [, alt_r=alt_r])
Low precision formulas for the Sun's coordinates and the equation of time From 2002 Astronomical Almanac, p. C24
"The following formulas give the apparent coordinates of the Sun to a precision of 0.01deg and the equation of time to a precision of 0.1min between 1950 and 2050; on this page the time argument n is the number of days from J2000"
Return value
a unit vector from Earth to Sun in GCI frame
Parameters
- JD in required
Julian Date, UTC time scale. May be scalar or 1D array
Keywords
- R out optional
distance from Earth to Sun in AU
- B0 out optional
Heliocentric latitude of sub-Earth point in degrees. This is the Sun's "nodding angle" in SNR. Positive if the northern hemisphere is tilted towards the earth, negative if southern.
- alpha out optional
Right ascension of Sun in degrees
- delta out optional
Declination of Sun in degrees
- lambda out optional
Ecliptic longitude of Sun in degrees (beta, ecliptic latitude, is zero in this low-precision formula)
- alt_r out optional private
Unit vector from Earth to Sun in GCI, calculated by an alternate method. You shouldn't use this, it's for debugging this function only.
File attributes
Modification date: | Tue Sep 11 20:41:18 2012 |
Lines: | 87 |
Docformat: | rst rst |