[alma-config]UTM coordinates, etc.

[Angel Otarola M.]

Dear Simon and Mark,

Just for completeness.

Attached to this note I am sending you copy of my calculations for the
determination of the "meridian convergence" and the "scale factor" for a
point near the site testing containers at Chajnantor.

Regarding the UTM cartographic projections, besides what Simon already
indicated on his email I can add the following:
1.- UTM is a so-called "conformal" cartographic projection. This means the
angles relations are kept the same as in the reference ellipsoid but there
is linear deformation as you move away from the central meridian.

2.- The linear scale is unity (1) only along the central meridian and then
increases as you move away from the central meridian, the UTM projection
was modified so that the scale factor at the central meridian corresponds
to 0.9996. This modification has been adopted in order to minimize the
maximum scale factor on the projected area of 6x6 degrees.

3.- The meridian convergence is negative to the east of the central
meridian and positive to the west. A negative value for the meridian
convergence indicates the Grid´s north is west of the geographic north.

Cheers,
Angel










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