[Spice_discussion] Summarizing CK and SPK files with Icy

[Ed Wright]

To: Dr. William Thompson
From: Ed Wright JPL/NAIF

Dr. Thompson,

>> How do I extract the start and end times from a CK file in Icy?

Icy includes interfaces to the routines used extract the contents of 
SPK and CK files. Last year, I needed SPK and CK segment data so to 
simplify the process I constructed simple IDL objects based on Icy to 
calls.


Below, please find example uses of these objects to retrieve various 
data items (including coverage times) from SPK and CK segments:

---SPK

  IDL> spk1 = obj_new( 'SPK', '/kernels/ULY-Ulysess/uly_spk_merge2.bsp')

  IDL> spk1->kernel_summary
  SPK summary for /kernels/ULY-Ulysess/uly_spk_merge2.bsp
      Body  Center Frame  Type    Seg start/end            ET start/end
       -55     399    11     1              641     -291488100.00000000
                                           4241     -291268927.71930838

       -55      10    11     1             4242     -291268927.71930838
                                          53712     -252654101.19489717

       -55       5    11     1            53713     -252654101.19489717
                                          60553     -245695692.58680630

       -55      10    11     1            60554     -245695692.58680630
                                        1743787      189345900.00000000

         3       0    11     2          1743788     -291643200.00000000
                                        1760194      189432000.00000000

         5       0    11     2          1760195     -291643200.00000000
                                        1765273      189432000.00000000

        10       0    11     2          1765274     -291643200.00000000
                                        1773502      189432000.00000000

       301       3    11     2          1773503     -291643200.00000000
                                        1826440      189432000.00000000

       399       3    11     2          1826441     -291643200.00000000
                                        1879378      189432000.00000000
  IDL> print, spk1->value( 'KERNEL' )
  /kernels/ULY-Ulysess/uly_spk_merge2.bsp

  IDL> print, spk1->value( 'BODY' )
           -55         -55         -55         -55           3           
5
            10         301         399

  IDL> print, spk1->value( 'CENTER' )
           399          10           5          10           0           
0
             0           3           3

  IDL> print, spk1->value( 'FRAME' )
            11          11          11          11          11          
11
            11          11          11

  IDL> print, spk1->value( 'SEG_START' )
           641        4242       53713       60554     1743788     
1760195
       1765274     1773503     1826441

  IDL> print, spk1->value( 'SEG_END' )
          4241       53712       60553     1743787     1760194     
1765273
       1773502     1826440     1879378

  IDL> print, spk1->value( 'ET_START' )
    -2.9148810e+08  -2.9126893e+08  -2.5265410e+08  -2.4569569e+08
    -2.9164320e+08  -2.9164320e+08  -2.9164320e+08  -2.9164320e+08
    -2.9164320e+08

  IDL> print, spk1->value( 'ET_END' )
    -2.9126893e+08  -2.5265410e+08  -2.4569569e+08   1.8934590e+08
     1.8943200e+08   1.8943200e+08   1.8943200e+08   1.8943200e+08
     1.8943200e+08

  IDL> print, spk1->value( 'TAGS' )
  KERNEL BODY CENTER FRAME TYPE SEG_START SEG_END ET_START ET_END


---CK, quite similar to SPK


  IDL> ck = obj_new( 'CK', 
'/kernels/genesis/gnssc_r_020506_020512_v1.bc')

  IDL> ck->kernel_summary
  CK summary for /kernels/genesis/gnssc_r_020506_020512_v1.bc
       Ins     Ref  Type Rates    Seg start/end          SCLK start/end
    -47000       1     3     1             1153   180508239160.00000000
                                         802154   180646286780.00000000

    -47000       1     3     1           802155   180646286780.00000000
                                         899486   180663075877.00000000

  IDL> print, ck->value( 'KERNEL' )
  /kernels/genesis/gnssc_r_020506_020512_v1.bc

  IDL> print, ck->value( 'INSTRUMENT' )
        -47000      -47000

  IDL> print, ck->value( 'REFERENCE' )
             1           1

  IDL> print, ck->value( 'TYPE' )
             3           3

  IDL> print, ck->value( 'RATES' )
             1           1

  IDL> print, ck->value( 'SEG_START' )
          1153      802155

  IDL> print, ck->value( 'SEG_END' )
        802154      899486

  IDL> print, ck->value( 'SCLK_START' )
     1.8050824e+11   1.8064629e+11

  IDL> print, ck->value( 'SCLK_END' )
     1.8064629e+11   1.8066308e+11

  IDL> print, ck->value( 'TAGS' )
  KERNEL INSTRUMENT REFERENCE TYPE RATES SEG_START SEG_END SCLK_START 
SCLK_END


I wrote the objects in IDL. Do they return the data of interest to you?

As always,
Ed Wright
ed.wright at jpl.nasa.gov
1-818-354-0371

-- 
DISCLAIMER: JPL requires notice in all electronic communication that
any and all opinions presented herein are my own and do not, in any
way, represent the opinion or policy of JPL, CalTech, NASA, or the US
Government.

Disclaimers are without standing on traffic from this domain.

I do not accept responsibility for unexpected collisions between NASA
vehicles and Alien cruisers, any resulting interplanetary war, or a
grumpy Kilrathi.