A “sensor” catalog file defines an instrument’s Field-of-View (FOV) location, orientation, and appearance. This is an example of a sensor catalog file for the CASSINI ISS NAC instrument:

{
   "version": "1.0",
   "name": "Cosmographia CASSINI Example",
   "items": [
      {
         "class": "sensor",
         "name": "CAS_ISS_NAC",
         "parent": "Cassini",
         "startTime": "1997-10-15 09:26:08.390 UTC",
         "endTime": "2015-08-01 01:58:52.000 UTC",
         "center": "Cassini",
         "geometry": {
            "type": "Spice",
            "instrName": "CASSINI_ISS_NAC",
            "target": "Saturn",
            "range": 45000,
            "rangeTracking": true,
            "frustumColor": [
               0, 
               1, 
               1
            ],
            "frustumBaseLineWidth": 3,
            "frustumOpacity": 0.3,
            "gridOpacity": 1,
            "footprintOpacity": 0.8,
            "sideDivisions": 300,
            "onlyVisibleDuringObs": false
         } 
      }
   ] 
}

The version and name attributes set the catalog format/content version (must be “1.0”) and the internal name of the catalog file.

The class attribute sets the object class to “sensor”.

The name attribute sets the name that will be used to identify the sensor object within Cosmographia.

The parent attribute contains the Cosmographia name for the spacecraft on which the sensor is mounted.

The startTime and endTime attributes set the sensor’s “lifetime” span within Cosmographia. These times are optional. When present they are normally set to the same start and end times as for the parent spacecraft.

The center attribute contains the Cosmographia name for the object at which the sensor FOV frustum tip will be centered. Normally it is set to the name of the Cosmographia name for the spacecraft. If desired, the tip location can be shifted to a different point on the spacecraft by using a combination of the trajectoryFrame property of the BodyFixed type with body set to the spacecraft (see Body Frame/Intermediate Frame Types) and the trajectory property of the FixedPoint type with the vector representing the desired location (see Trajectory Types).

The geometry property defines how the sensor FOV frustum is visualized. The example above tells the program to obtain the sensor’s FOV parameters from SPICE (“type”: “Spice”) for the instrument with the SPICE name “CAS_ISS_NAC” (name). It sets Saturn as the sensor’s target (target), sets the frustum extent to 45,000 km (range), and turns on dynamic adjustment of the frustum extent based on the range to the target (rangeTracking).  It uses additional attributes to set frustum color in RGB (color), the width of the line circumscribing its base (frustumBaseLineWidth [available in Cosmographia 4.1 or later]), frustum opacity (frustumOpacity), frustum grid opacity (gridOpacity), and FOV footprint opacity (footptinyOpacity) as well as the number of divisions in each frustum side (sideDivisions) that will be used to draw intercept lines of  FOV sides with the target body. It finally sets the flag to make FOV visible at all times rather than only during observations (onlyVisibleDuringObs).

A more detailed description of some of the parameters in this catalog file is provided in the “CATALOG FILE DEFINING A SENSOR” section of the Cosmographia-SPICE User’s Guide.