FIND @name CENTRAL MERIDIAN
(2:2){ OF @body
| FROM @body }
BETWEEN @number AND @number
(0:1){ WITHIN @name }
STEP SIZE @number(0:)
This command locates intervals during which the planetographic longitude of
the central meridian OF a target body as seen FROM an observing body lies
BETWEEN a pair of specified values. The central meridian is the meridian that
runs through the apparent sub-observer point on the target body. (That is,
the surface intercept point of the vector from the center of the observer to
the center of the target, not the point on the target body closest to the
observer.)
In the following example, the FIND CENTRAL MERIDIAN command is used to locate
intervals during which the Loki Patera region on Io (planetographic longitude
50 degrees, latitude 15 degrees) is near the sub-Earth point. The search
interval is restricted to intervals (determined previously) when Io is not
occulted by, eclipsed by, or in transit across Jupiter.
IMPORT IO_CLEAR.WIN AS CLEAR;
FIND LOKI CENTRAL MERIDIAN OF IO
FROM EARTH BETWEEN 40 DEGREES AND 60 DEGREES
WITHIN CLEAR
STEP SIZE 10 MINUTES;
The order of the values following the keyword BETWEEN is significant. For
example
BETWEEN 10 DEGREES AND 50 DEGREESrefers to an arc of 40 degrees, while
BETWEEN 50 DEGREES AND 10 DEGREESrefers to an arc of 320 degrees.