SpiceDouble clight_c ( void )
Return the speed of light in a vacuum (IAU official
value, in km/sec).
The function returns the speed of light in vacuo (km/sec).
The function returns the IAU official value for the speed of light
in vacuo: 299792.458 km/sec.
The function always returns the constant value shown above.
The following example uses clight_c to determine the one-way
light-time (tau) to an object whose position relative to an
observer is contained in pos.
tau = vnorm_c ( pos ) / clight_c ();
Note that the SPK readers
return the one-way light time as an output, for example
spkez_c ( ..., &tau );
N.J. Bachman (JPL)
W.L. Taber (JPL)
I.M. Underwood (JPL)
E.D. Wright (JPL)
-CSPICE Version 1.0.2, 07-FEB-2008 (EDW) (NJB)
Corrected typos in header titles:
Detailed Input to Detailed_Input
Detailed Output to Detailed_Output
Updated example to show pointer output argument
`tau' and list other high-level SPK routines that
return light time. Call to bodmat_c was removed
-CSPICE Version 1.0.1, 11-NOV-2006 (EDW)
Added Parameters section header.
-CSPICE Version 1.0.0, 16-APR-1999 (EDW)
measured velocity of light in a vacuum