Conversion between longitude, right ascension and local time - DEPRECATED
[par_out] = CL_op_locTimeG50(cjd, type_par, par, type_par_out [,ut1_utc]) [res1,..,resN] = CL_op_locTimeG50(cjd, type_par, par, [type1,..,typeN] [,ut1_utc]) [par_out] = CL_op_locTimeG50(cjd, type_par, par, 'all' [,ut1_utc])
This function is deprecated.
Replacement function: CL_op_locTime
Performs various conversions between quantities defined in the Earth equatorial plane.
These quantities are: longitude, right ascension, true or mean local time. Additional quantities are computed: sidereal time and right ascension of (true or mean) Sun direction.
Quick definitions:
- The right ascension (ra) is the angle in the equator from the inertial reference axis (in the equatorial plane) chosen.
- The longitude (lon) is the angle in the equator from the Greenwich meridian.
- The sidereal time (sidt) is the angle between the inertial axis and the Greenwich meridian.
- The true solar angle (tsa) is the angle from the projection of the Sun direction onto the equatorial plane.
- The mean solar angle (msa) is the "mean" value of the true solar angle, that is the angle from a fictitious "mean" direction of the Sun that is rotating uniformly in the equatorial plane (i.e. unaffected by the equation of time).
The relations between the different parameters are as follows:
ra = lon + sidt
tsa = ra - stra
msa = ra - smra
smra = sidt - 2*pi*decimal(t) + pi
tlh = tsa * 12/pi + 12
mlh = msa * 12/pi + 12
where:
- sidt: sidereal time.
- stra: right ascension of the direction.
- smra: right ascension of the "mean" planet to Sun direction.
- t is the number of days from some origin at midnight (UT);
- decimal(t) = t - floor(t) (decimal part).
Important notes:
- The function is only valid for the Earth.
- The inertial axis (origin for right ascensions or sidereal time) is the x-axis of the Gamma 50 (Veis) reference frame.
Remark: Some output parameters do not depend on all the inputs. Examples:
lon = CL_op_locTimeG50(cjd, 'lon', 0, 'lon') => cjd should not be needed in theory(but it is used in practice!)
sidt = CL_op_locTimeG50(cjd, 'lon', 0, 'sidt') => the result does not depend on 'lon'!)
Deprecated use:
- The use of tlt and mlt is deprecated.
- Use respectively tsa and msa instead.
Time from 1950.0 in the UTC time scale (1xN or 1x1)
(string) Name of the input parameter. It can be 'lon' (longitude), 'ra' (right ascension), 'tsa' (true solar angle), 'tlh' (true local time expressed in hours), 'msa' (mean solar angle), 'mlh' (mean local time expressed in hours).
Value of the input parameter expressed in degrees for lon, ra, msa, tsa and hours for mlh and tlh. (1xN or 1x1).
(string) Name(s) of the output parameter(s). It can be 'lon', 'ra', 'tsa', 'tlh', 'msa', 'mlh' (see type_par), or 'sidt' (sidereal time), 'stra' (Sun true right ascension) 'smra' (Sun mean right ascension), or a vector of any of these, or 'all'. (1xM)
Offset between UT1 and UTC (s) = Time of some event in UT1 minus time of the same event in UTC.
Value(s) of the output parameters. As many arguments are needed as there are names in 'type_par_out', except if type_par_out is 'all' in which case varargout is a structure (with fields names equal to the names in type_par_out). Units are radians or hours depending on the parameter.
CNES - DCT/SB