Installing MeqTrees 1.2

As of MeqTrees 1.2, we provide binary packages for the following distributions:

Currently, the best-tested distro is 10.04 64-bit, since that's what our development machines use. In any case, please treat these packages on an as-is basis. We're a small group, and it is simply impossible to thoroughly test the binary installation on multiple platforms with our limited manpower. Forgive us if any obvious bugs turn up, report them, and we'll make new binary packages if needed.

Support for other distros may be added upon request (or else see "Building From Source" below).

deb-based systems (Ubuntu)

First, download an appropriate repository package from http://www.oerc.ox.ac.uk/~meqtrees/repos/astro/release/ (NB: you may see directories corresponding to other distros: ignore them, they are not supported). Install the repository package with a package installer such as GDebi (your browser will probably offer to run an installer anyway when you go to download the .deb file), or from the command line:

From this point on, the Oxford repository is registered with your package management system, and you can install meqtrees just like any other standard software package supplied by your distro. Use apt-get or your favourite package manager (Synaptic, etc.) to refresh the repositories and install the meqtrees package. For apt-get you would use the following commands:

rpm-based systems (Fedora)

A similar procedure applies to rpm-based systems. First, download and install an appropriate repository .rpm from the link above. Your browser will probably offer to run an installer when you go to download the .rpm file. If you prefer the command line, download the .rpm file and install with rpm:

From this point on, the Oxford repository is registered with your package management system, and you can install meqtrees just like any other standard software package supplied by your distro. Use yum or your favourite package manager (Add/remove software, etc.) to refresh the repositories and install the meqtrees package. For yum you would use the following commands:

Other recommended software

The makems package is very useful for simulations, since it can create Measurement Sets for arbitrarily-defined telescopes.

The tigger package (not working on 10.04 32-bit, see below) is a FITS image viewer and sky model manager developed specifically for MeqTrees. Other FITS viewers out there include DS9 from SAO, Karma by Richard Gooch, and the casaviewer tool in CASA.

The owlcat package is a set of simple command-line scripts for manipulating MSs, flagging, making simple plots, etc. Install it and see owlcat -h for details.

Known issues and gotchas

Ubuntu 10.04 32-bit issues

At time of release (Sep 2011), the PyQwt5 package in this distro was broken (see https://bugs.launchpad.net/ubuntu/+source/pyqwt5/+bug/672509, and vote the bug up, maybe they'll fix it!) To check if your PyQwt5 is broken, run this simple script: qwt5check.py. MeqTrees itself will run, but some visualizations will cause the browser to crash, and Tigger won't run at all. Our recommendation is to avoid this platform until and unless the bug is fixed.

Alternatively, you can build your own PyQwt5 from source, see Downloading/BuildingPyQwt5 for details.

lwimager weights, and the CASA imager

If the lwimager fails or produces null images, check its text output -- you will probably see a "weights all zero" message. This is because you haven't specified a UV-weighting (or, equivalently, have set it to "default" in the TDL Exec menu).

The UV-weighting is a persistent parameter: every time you change it, it gets saved in the IMAGING_WEIGHT column of the MS. You can then rerun the imager with "default" weighting to reuse the existing weighting. This is actually pretty useful, since it saves some runtime, and also allows you to manipulate the weights offline. The downside is, if you have a new MS, the IMAGING_WEIGHT column is probably null or missing, so running the imager with "default" weights will fail (this often confuses people).

Another confusing imager "feature" is that data flags are only applied during the weighting procedure. Flagged data receives a weight of 0. Flags are not reapplied during subsequent imaging! So if you set your weights, then flag some more data, these flags have no effect on your image until you reset the imaging weights again. I have been caught out by this myself on a number of occasions.

Note also that the CASA imager is built on top of the same casacore/casarest libraries, but it has a fixed default of radial weighting.

Funny package sizes reported

When using apt to install the packages, you may see some bogus size indications such as "After this operation, 281TB of additional disk space will be used" (or in some cases "freed"). These are due to a bug in the packaging system -- in actual fact all the packages put together are ~100MB at best, with perhaps ~500MB of additional dependencies from the standard repository (some of which may already be installed on your system).

Building From Source

Brave souls may choose to build MeqTrees from source. You will need to check out source from our subversion repository. Please refer to BuildingTimba for further instructions.

Old Pages

The old (release 1.1.1) Downloading page has been renamed to Downloading-1.1.1.

Downloading (last edited 2011-10-12 17:54:13 by OlegSmirnov)