The Haystack Observatory Postprocessing System (HOPS) is a software package designed to manipulate data generated by the MkIV or DiFX VLBI correlator. It is written in C for Unix computers, and emphasises quality-control aspects of data processing. It sits between the correlator and an image-processing package, and performs basic fringe-fitting, data editing, problem diagnosis, and correlator support functions.
More information about HOPS is available on the Haystack HOPS web page.
The HOPS package can be built as part of the normal installation process if you include the
–withhops flag on the command-line of
install-difx (See DiFX Installation).
It may also be installed independently of the DiFX build by following the instructions in the file
README.difx.txt in the source directory (
Following installation, you will need to adjust your PATH and other environment variables to find the HOPS tools. A script
hops.bash should have been built and installed when you installed the tools.
Once you source this script (
which hops.bash) via
the HOPS tools will then be at the head of your PATH. You can get help about the environment with
and help on the individual tools with
To use HOPS on DiFX-correlated data, you first need to use difx2mark4 to convert the native DiFX output into the MkIV data format. This will create an experiment directory hierarchy under the experiment number. The HOPS environment variable DATADIR should be set to the parent of this directory.
This installation of HOPS is a vendor branch to the DiFX SVN repository offered as a convenience to the DiFX community, and as such is not the master source for the code. Thus changes to the HOPS code in the DiFX SVN repository should not be made casually, or without consultation with Haystack (gbc [at] haystack [dot] mit [dot] edu) or they will be lost.