[alma-config]A complete design

[Simon Radford]

Frederic,

The "exact" definition of UTM coordinates involves reference ellipsoids, coordinate projections, map datums, and other topics of little interest to us. In practical terms, UTM coordinates measure offsets in meters North and East from a reference point
(far) outside our area of interest. The GPS receivers are setup for these coordinates.

Bryan's mask and the maps are all based on UTM coordinates (SAm56). (Look in the FITS headers.)

The adopted center of the array is Chajnantor South:
       7453228.830 N      627807.166 E

Where is the center of your coordinate system? If you used Chajnantor South, just add those offsets to your locations. If you subtracted some offset from Bryan's mask, add it back.

The important thing is a list of positions.

Simon

PS: For "Chajnantor South," there are a couple of sets of coordinates, differing by 100-200 m, floating about in various reports. This may make a difference for positions near the edges of the mask. To avoid confusuon, lets all use the same reference
position, given above.

Coordinates, etc.
http://www.tuc.nrao.edu/alma/site/Chajnantor/maps/coordinates.html

Maps, etc.
http://www.tuc.nrao.edu/alma/site/Chajnantor/maps/

Mask
ftp://ftp.aoc.nrao.edu/pub/staff/bbutler/newmask5-new.FITS.gz