Format for Spacecraft Optical Navigation Observations

The observations are contained in a Picture Sequence File (PSF) which is
a text file consisting of a series of four different FORTRAN namelists:
  1. The $ID namelist identifies the file.
  2. The $CAM namelist contains data pertaining to the camera models for
      the cameras on the spacecraft.
  3. The $PIC namelist contains variables that define a picture.
  4. The $IM namelist contains variables that define one image in a picture
     Depending on the nature of the image - a planet, a satellite, or a star -
     different variables are written to the output file.

The order of the namelists is as follows:
  $ID
  $CAM
  $PIC for the first picture.
     $IM for the first image in the first picture.
     :
     $IM for the last image in the first picture.
     $IM with  IMG='END' to denote the end of the first picture.
  :
  $PIC for the last picture.
     $IM for the first image in the last picture.
     :
     $IM for the last image in the last picture.
     $IM with  IMG='END' to denote the end of the last picture.
  $PIC with  PICNM='END' to denote the end-of-file.


The contents of the namelists are:

$ID Namelist Variables
NameTypeDim. Description
SCID C1 The spacecraft ID.
PSFID C1 Identification of this PSF.
PSFTIMC1 Calendar date and time at which this PSF was generated.
PSFPRGC1 The name of the program that last modified this PSF.
PSFCOMC3 Additional optional documentation about the PSF.
EQUNOXI1 The equinox of the file, either 1950 or 2000.
NCAM I1 Number of spacecraft cameras.

$CAM Namelist Variables}
NameTypeDim. Description
CAMID C NCAM Name of each camera.
FL DPNCAM Focal length in millimeters of each camera.
PLCTR DP2,NCAM Center of each camera in pixel and line.
PLSIZ DP4,NCAM Minimum pixel, maximum pixel, minimum line, and maximum line of the hardware field of view of each camera.
KMAT DP2,3,NCAM The transformation matrix K for each camera.
EM DP6,NCAM The distortion coefficients for each camera.
OFFSET DP3,NCAM Offset angles in elevation, cross-elevation, and twist from the scan platform to each camera body; expressed in degrees.

$PIC Namelist Variables}
NameTypeDim. Description
PICNM C 1 Name (often the FDS count) of this picture.
PICNO I 1 Number of this picture on the file.
TOB C 1 Calendar date of the end of the exposure in UTC.
CAMERA C 1 Camera ID for this picture.
EXPTIM DP1 Exposure time, in seconds.
PICDEL I 1 Picture deletion flag: 0 to keep the picture, any positive integer to delete it from processing.
RA DP1 Right ascension,
DEC DP1 declination, and
TWIST DP1 twist pointing angles of the scan platform, in degrees, with respect to inertial coordinates.

$IMG Namelist Variables}
NameTypeDim. Description
IMG C 1 Name of the image. This is the body name if the image is the center of a body or the catalog number if the image is a star.
IMGTYP C 1 Type of the image: PLAN, SAT, ROCK, or STAR for planet centers, satellite centers, rock centers, and stars, respectively.
IMGID I 1 ID number of the image. This is the body code number for planets, satellites, and rocks; or the catalog number for a star.
USE I 1 Image deletion flag: 0 to keep the image, any positive integer to delete it.
Z DP2 The observed pixel and line location of the image.
ZC DP2 The local correction which, when subtracted from Z, produces the effective pixel and line location of the image.
SIG DP2 The uncertainty in Z, in pixel and line.
STRA DP1 Right ascension and
STDEC DP1 declination of the star in degrees with respect to inertial coordinates corrected for parallax and proper motion.