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scs2e_c
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Procedure
Abstract
Required_Reading
Keywords
Brief_I/O
Detailed_Input
Detailed_Output
Parameters
Exceptions
Files
Particulars
Examples
Restrictions
Literature_References
Author_and_Institution
Version
Index_Entries

Procedure

   void scs2e_c ( SpiceInt          sc, 
                  ConstSpiceChar  * sclkch, 
                  SpiceDouble     * et      ) 

Abstract

 
   Convert a spacecraft clock string to ephemeris seconds past 
   J2000 (ET). 
 

Required_Reading

 
   SCLK 
   TIME 
 

Keywords

 
   CONVERSION 
   TIME 
 

Brief_I/O

 
   Variable  I/O  Description 
   --------  ---  -------------------------------------------------- 
   sc         I   NAIF integer code for a spacecraft. 
   sclkch     I   An SCLK string. 
   et         O   Ephemeris time, seconds past J2000. 
 

Detailed_Input

 
   sc             is a NAIF ID code for a spacecraft, one of whose 
                  clock values is represented by sclkch.  The set of 
                  supported spacecraft clocks is listed in the SCLK 
                  Required Reading. 
 
   sclkch         is a character string representation of the 
                  spacecraft clock value that corresponds to ET, for 
                  the spacecraft specified by the input argument sc. 
                  sclkch is an absolute spacecraft clock time, so 
                  partition information should be included in this 
                  string.  The precise format of sclkch is specified 
                  in the SCLK Required Reading. 
 

Detailed_Output

 
   et             is the epoch, specified as ephemeris seconds past 
                  J2000, that corresponds to sclkch. 
 

Parameters

 
   None. 
 

Exceptions

 
   1)  This routine assumes that that an SCLK kernel appropriate 
       to the spacecraft clock identified by the input argument SC 
       has been loaded.  If an SCLK kernel has not been loaded, 
       does not contain all of the required data, or contains 
       invalid data, error diagnoses will be performed by routines 
       called by this routine.  The output argument et will not 
       be modified. 
 
   2)  When using SCLK kernels that map SCLK to a time system other 
       than ET (also called barycentric dynamical time---`TDB'), it 
       is necessary to have a leapseconds kernel loaded at the time 
       this routine is called.  If a leapseconds kernel is required 
       for conversion between SCLK and ET but is not loaded, the 
       error will be diagnosed by routines called by this routine. 
       The output argument et will not be modified. 
 
       The time system that an SCLK kernel maps SCLK to is indicated 
       by the variable SCLK_TIME_SYSTEM_nn in the kernel, where nn 
       is the negative of the NAIF integer code for the spacecraft. 
       The time system used in a kernel is TDB if and only if the 
       variable is assigned the value 1. 
 
 
   3)  Invalid values of sclkch will be diagnosed by routines called 
       by this routine.  The output argument et will not be modified. 
 

Files

 
   None. 
 

Particulars

 
   This routine is provided as a convenience; it is simply shorthand 
   for the code fragment 
 
      scencd_c ( sc, sclkch, &sclkdp );
      sct2e_c  ( sc, sclkdp, &et     ); 
  

Examples

 
   1)  Find the state (position and velocity) of Jupiter, as seen 
       from the Galileo spacecraft, at the epoch corresponding to 
       the SCLK value 
 
          2 / 3110578:89:09 
 
       The digit "2", followed by the forward slash, indicates that 
       the time value is in the second mission partition. 
 
 
       During program initialization, load the leapseconds and 
       SCLK kernels.  We will pretend that these files are named 
       "leapseconds.ker" and "gllsclk.ker".  To use this code 
       fragment, you must substitute the actual names of these 
       kernel files for the names used here. 
 
          /.
          Load leapseconds and SCLK kernels: 
          ./
          furnsh_c ( "leapseconds.ker" ); 
          furnsh_c ( "gllsclk.ker"     );
 
          /.
          Load an SPK file (again, a fictitious file) 
          containing an ephemeris for Jupiter and the 
          GLL orbiter's trajectory. 
          ./
          spklef_c ( "gllspk.ker", &handle );
 
          /.
          The Galileo spacecraft ID is -77.  Convert our SCLK 
          string to ephemeris seconds past J2000, which is the 
          time representation expected by spkez_c. 
          ./
          scs2e_c ( -77, "2 / 3110578:89:09", &et ); 
 
          /.
          Find the state of Jupiter (body 599) as seen from Galileo 
          at time et.  To use spkez_c, you must first load an SPK 
          kernel, using the routine spklef_c. 
          ./
          spkez_c ( 599, et, refsys, corr, -77, state, &lt ); 
 
 
 
   2)  Convert a Voyager 2 SCLK value to UTC, using calendar format, 
       with 3 digits of precision in the seconds component. 
 
       Again, your initialization code must load the leapseconds 
       and SCLK kernels: 
 
          /.
          Load leapseconds and SCLK kernels: 
          ./
          furnsh_c ( "leapseconds.ker" );
          furnsh_c ( "vgr2sclk.ker"    );
 
 
       To find the UTC value corresponding to Voyager 2 SCLK 
       string 

          11389.20.768 

       you can use the code fragment 
 
          scs2e_c  ( -32,  "11389.29.768",          &et  ); 
          et2utc_c (  et,  "c",      3,    UTCLEN,  utc  );
          
       where UTCLEN is a constant indicating the available
       room in the string utc.  A value of 25 characters suffices.
       

Restrictions

 
   1)  An SCLK kernel appropriate to the spacecraft clock identified 
       by SC must be loaded at the time this routine is called. 
 
   2)  If the SCLK kernel used with this routine does not map SCLK 
       directly to barycentric dynamical time, a leapseconds kernel 
       must be loaded at the time this routine is called. 
 

Literature_References

 
   [1]   SPK Required Reading 
 

Author_and_Institution

 
   N.J. Bachman   (JPL) 
 

Version

   -CSPICE Version 1.1.1, 14-AUG-2006   (EDW)

      Replace mention of ldpool_c with furnsh_c.

   -CSPICE Version 1.1.0, 08-FEB-1998 (NJB)  
   
       References to C2F_CreateStr_Sig were removed; code was
       cleaned up accordingly.  String checks are now done using
       the macro CHKFSTR.
       
   -CSPICE Version 1.0.0, 25-OCT-1997 (NJB)
   
      Based on SPICELIB Version 1.0.2, 10-APR-1992 (NJB) (WLT)

Index_Entries

 
   spacecraft_clock string to ephemeris time 
 
Wed Apr  5 17:54:42 2017