FIND @name SEPARATION
(2:2){ OF @body @body
| FROM @body }
(1:1){ GREATER THAN @number
| LESS THAN @number
| EQUAL TO @number
| BETWEEN @number AND @number
| ABSOLUTE MINIMUM PLUS @number(0:)
| ABSOLUTE MAXIMUM MINUS @number(0:)
| ABSOLUTE MINIMUM
| ABSOLUTE MAXIMUM
| LOCAL MINIMUM
| LOCAL MAXIMUM }
(0:1){ WITHIN @name }
STEP SIZE @number(0:)
This command locates intervals during which the apparent angular separation
OF two target bodies as seen FROM an observing body satisfies a specified
constraint.
Both target bodies are represented by spheres, with radii equal to the longest equatorial radii of the tri-axial ellipsoids used to model the respective bodies.
The separation between the bodies is the angle between the closest points on the limbs of the spheres, as viewed from the vantage point of the observer.
If the limbs overlap, the separation is negative. (In this case, the separation is the angle between the centers of the spheres minus the sum of the apparent angular radii of the spheres.)
In the following example, the FIND SEPARATION command is used to determine
intervals when Io is neither occulted by nor in transit across Jupiter.
FIND CLEAR SEPARATION OF IO JUPITER
FROM EARTH GREATER THAN 0
STEP SIZE 1 HOUR;
Note that while these could be determined using the FIND OCCULTATION and FIND
TRANSIT commands, FIND SEPARATION is a better choice whenever the satellite
merely needs to be clear of the planet, regardless of which is in front of
the other.
In the following example, the FIND SEPARATION command is used to determine
intervals when the separation between Io and Europa is at a local minimum.
FIND CLOSE SEPARATION OF IO EUROPA
FROM EARTH LOCAL MINIMUM
STEP SIZE 15 MINUTES;