central meridian

central meridian

The imaginary N–S line bisecting the disk of a planet, satellite, etc., used as a reference.

central meridian

[′sen·trəl mə′rid·ē·ən]
(astronomy)
The meridian of a planet that crosses the center of the visible face of the planet at a given instant.

central meridian

central meridian
The longitudinal line of symmetry of a map projection and, generally, a baseline for referencing the projection to the associated grid coordinate system. As such, grid north and true north are coincident along the central meridian, but at any other point of the projection, grid north and true north diverge as a function of geodetic latitude and longitudinal distance from the central meridian as a result of the convergence of the meridians. Most map projections portray meridian convergence, but one notable exception is the Mercator Projection.
References in periodicals archive ?
And here are the times, in Universal Time, when the Great Red Spot should cross Jupiter's central meridian.
Once the longitude of the central meridian has been established you can easily work out the longitude of groups on the disk by adding degrees for those west of the meridian and subtracting degrees east of the meridian.
Note that the value of N here is the North ordinate from the origin which is the intersection of the Central Meridian and the Equator, and the False Northing therefore needs to be added in later.
In the summer of 1997, amidst the devolution of Scotland and Wales and the death of Diana, geographer and award-winning writer, Nicholas Crane, equipped himself with a camouflaged umbrella and embarked on a remarkable walk straight along England's central meridian.
Because I was walking along a route I didn't choose - there's only one central meridian - I came across places I'd never heard of.
It takes 50 minutes for a feature to rotate from Jupiter's central meridian halfway to the preceding limb.
AR1043 N25[degrees]/324[degrees] continued across the disk from the previous month, approaching the central meridian on Feb 1 type Hsx with an area of 30 millionths.
The predicted times when the center of the Great Red Spot crosses the central meridian are listed in Sky & Telescope or can be obtained on our web site.

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