Selenographic Coordinates

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selenographic coordinates

[sə¦lē·nə¦graf·ik kō′ȯrd·ən·əts]
(astronomy)
A coordinate system for specifying positions on the moon's surface relative to the moon's center, consisting of selenographic latitude and longitude, or of a cartesian coordinate system.

Selenographic Coordinates

 

numbers by means of which the positions of points on the surface of the moon are determined. Selenographic latitude and longitude are used as such coordinates.

The latitude of a point is the angular distance of the point from the lunar equator and is measured along the meridian passing through the point. North of the equator, the latitude is positive; south of the equator, it is negative. The north pole here is defined as the pole at which an observer sees the moon to be rotating in a counterclockwise direction.

The longitude of a point is the angle between the plane of the meridian of the point and the plane of the initial meridian. The initial meridian is defined as the meridian whose plane passes through the center of the earth when the libration in longitude (seeLIBRATION OF THE MOON) is equal to zero. Longitudes measured to the east of the initial meridian are regarded as positive; longitudes measured to the west of it are considered negative. It should be noted that this definition of positive and negative does not conform to the general rule established for planeto-graphic coordinates.

References in periodicals archive ?
All his drawings are annotated with date and time and technical data relative to the time of observation, such as seeing conditions, colongitude, selenographical latitude, and libration.
Inspection of the data shows (with three exceptions only) that M5 could be traced until colongitude [C.
Original drawings, comprising 1 (one) title sheet, and 8 (eight) A4 size sheets of cartridge paper containing 43 (forty-three) drawings, numbered 1-43 consecutively and is described as follows: 'The progress of illumination during the lunar day showing the changing aspects in the high south latitude region embraced by the mountains designated M1 to M5 and arranged in order of solar colongitude.
The Plato 'hook', as it is often described, (2) is not readily observed, since its appearance is critically dependent upon a particular combination of selenographic colongitude, libration and topography.
The resulting image (Figure 4), taken on 2009 June 1 at 20:03 UT at colongitude 14.
The interior topography of Cassini A can indeed suggest a double crater under certain lighting conditions, and the attached image (Figure 1) taken by myself on 2008 December 6, when the colongitude value was 18.
Jamieson to Wilkins' descriptions, we were able to infer a lunar phase of approximately 60%, with the Moon exceeding the first quarter; a colongitude between 16[degrees]-17[degrees], corresponding to a solar altitude over Cassini A between 16.
Figure 11 displays the crater Cassini A under a solar angle and colongitude similar to, though slightly later than, the inferred time for the observation carried out at the Meudon Observatory.