DESIGNATE SOLAR MERIDIAN

Syntax

Fixed

   DESIGNATE @int(1001:10099)
      CENTER @body
      REFERENCE SOLAR MERIDIAN
      (2:3){ LATITUDE  @number
           | LONGITUDE @number
           | @options
           | RADIUS    @number }
      (0:3){ FROM  @calendar
           | TO    @calendar
           | EPOCH @calendar }

Moving

   DESIGNATE @int(1001:10099)
      CENTER @body
      REFERENCE SOLAR MERIDIAN
      (2:3){ LATITUDE  (1:2)@number
           | LONGITUDE (1:2)@number
           | @options
           | RADIUS    (1:2)@number }
      EPOCH @calendar
      (0:2){ FROM @calendar
           | TO   @calendar }

Description

When creating a designated object in this system, you must specify the latitude and longitude of the object. The radius is optional, and defaults to the radius of the reference sphere.

Definition

The solar meridian frame is a spherical coordinate system centered at the reference body. The radius of the reference sphere is the largest semi-major axis of the tri-axial ellipsoid used to model the body. The equator of the frame contains the sub-solar and sub-Earth points on the reference sphere. The reference meridian (zero degrees longitude) of the frame contains the sub-solar point.

By definition, the portion of the terminator visible from earth is at 90 degrees longitude.

Examples

The following designated object moves along the terminator of Mars.

   DEFINE TERM_SCAN 1001;
 
   DESIGNATE TERM_SCAN
   CENTER MARS
   REFERENCE SOLAR MERIDIAN
             LONGITUDE  90 DEGREES
             LATITUDE   -30 DEGREES 10 DEGREES/HOUR
             EPOCH 1 SEP 1990 12:00:00
             FROM  1 SEP 1990  9:00:00
             TO    1 SEP 1990 15:00:00 ;