SpiceDouble b1950_c ( void )
Return the Julian Date corresponding to Besselian Date 1950.0.
None.
CONSTANTS
The function returns the Julian Date corresponding to Besselian
date 1950.0.
None.
The function returns 2433282.42345905, the Julian Date corresponding
to Besselian Date 1950.0 as reported by Lieske [1].
None.
Error free.
None.
Lieske [1] defines a mapping from Julian Ephemeris Date
to Besselian:
BE = 1900. + (JED - 2415020.31352)/365.242198781
The inverse mapping being:
JED = (BE - 1900.)*365.242198781 + 2415020.31352
The following code fragment illustrates the use of b1950_c.
/.
Convert Julian Date to UTC seconds past the reference
epoch (b1950_c).
./
spref = ( jd - b1950_c() ) * spd_c();
None.
[1] Jay Lieske, ``Precession Matrix Based on IAU (1976)
System of Astronomical Constants,'' Astron. Astrophys.
73, 282-284 (1979).
W.L. Taber (JPL)
I.M. Underwood (JPL)
-CSPICE Version 2.0.0, 01-SEP-2005 (EDW)
This routine now returns the value reported in the Lieske
paper:
2433282.42345905
The same value returned by the FORTRAN SPICELIB routine
B1950.
This routine previously returned the value reported in the
"Explanatory Supplement to the Astronomical Almanac", 1992,
page 699:
2433282.423
The ESAA value describing a truncation of the Lieske value.
The difference between the two values expressed as seconds
yields approximately 39.662 seconds.
-CSPICE Version 1.0.1, 08-FEB-1998 (EDW)
Corrected and clarified header entries.
-CSPICE Version 1.0.0, 25-OCT-1997 (EDW)
besselian date 1950.0
Link to routine b1950_c source file b1950_c.c
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