Specifying antenna/station positions and diameters

Picking an ALMA configuration

This plot gives a quick estimate of the beam size for a zenith-transiting source. The X axis is configuration number e.g. "almaconfig.out20":

The actual configurations are stored in text files (so you can make your own once you know what you are doing; functionality to more easily simulate any current array will be present in the next patch).

ALMA (and ACA) configurations are located in the data repository, which should have come with your installation. Here's how to find it:
CASA <10> repodir=os.getenv("AIPSPATH").split(' ')[0]+"/data/alma/simmos/"
CASA <11> antennalist=repodir+"almaconfig.out20"

If you prefer to just download the text files, here they are:
  • for OLD CASA / almasimmos (v2.3, release before June 2009): almaconfigs.tgz
  • for NEW CASA / simdata (v2.4 ~June 2009 or alpha prerelease from remy) configs.tgz

suggestalmaconfig.py will recommend a configuration given a desired resolution, frequency, and source declination. It doesn't know about the ACA yet, so if it recommends O-01 you should consider manually picking an ACA configuration. You will also need these data files of beam summary tables:beamsummaries.tar.gz

File format

simdata reads the antenna positions from an ASCII file with four columns: X,Y,Z, and diameter. For example for ALMA,

  1. UTM-X (Easting; meters).
  2. UTM-Y (Northing; meters).
  3. Z (Altitude in meters)
  4. Diameter (meters). simdata uses a primary beam calculated using Airy patterns for the diameters you specify and a 1m diameter circular blockage in the center of each antenna or station.

Comments and headerl lines start with a #
You can specify several coordinate systems, using the comment lines as "headers" e.g.
# observatory = VLA
# coordsys = XYZ
and then input coordinates in X,Y,Z earth-centered ITRF.

You must specify observatory and coordsys in the header. See configs.tgz for examples (ALMA, EVLA, SMA, CARMA, etc)

email rindebet at nrao.edu if you have questions.
Topic attachments
I Attachment Action Size Date Who Comment
beamsummaries.tar.gzgz beamsummaries.tar.gz manage 8 K 2009-01-29 - 15:40 RemyIndebetouw beam summary tables
beamsummary.pngpng beamsummary.png manage 24 K 2009-01-30 - 08:40 RemyIndebetouw  
configs.tgztgz configs.tgz manage 7 K 2009-05-20 - 10:44 RemyIndebetouw configuration files
Topic revision: r5 - 2009-05-20, RemyIndebetouw
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