Synthetic data generation package for the Event Horizon Telescope

Installation

1. Use docker if you'd like to be system independent.

2. The included Dockerfile builds a container for Kernsuite 7 (Ubuntu 20.04) and downloads, compiles and installs AATM (the only external dependency)

AATM v0.5: mean atmospheric simulator (average opacities, sky brightness temp). (Download mirrored here)

3. It also creates a user (mequser) with password "meq" and sudo privileges. Be aware that Docker has issues separating superuser privileges on containers from those on their hosts!

Running MeqSilhouette

To run this synthetic data generator, you need:

1. a driver script (e.g. driver/run_meqsilouette.py)
2. a configuration file (input/eht230.json is an example. The file 'jsonformat.txt' explains each parameter.)

The software can be run in three primary modes:

###a) Through the terminal

$python driver/run_meqsilhouette.py input/eht230.json

###b) In a Juypter (ipython) Notebook

Start up notebook

from run_meqsilhouette import *

config = '/path/to/config.json' sim = run_meqsilhouette(config)

###c) In a Docker container

While setting up the required enviroment to run MeqSilhouette is just a few step process (for Ubuntu 14.04, 16.04), one can avoid system dependencies entirely with Docker.

###d) In a virtual environment

A number of python packages must be installed before MeqSilhouette could be run in a virtual environment. The following can be installed using pip install:

• numpy
• python-casacore==2.1.2 (to get pyrap to run)
• pyfits
• scipy==0.17 (to avoid the "Incorrect qhull library called" error)
• astLib
• termcolor
• matplotlib
• seaborn
• pandas
• mpltools

If an ImportError is thrown by pyfits for the modules gdbm and/or winreg, a quick and dirty fix is to open the file

/path-to-virtualenv/lib/python2.7/site-packages/pyfits/extern/six.py

and comment out the lines:

MovedModule("dbm_gnu", "gdbm", "dbm.gnu")

MovedModule("winreg", "_winreg")

Configuration file

All paths are relative to $MEQS_DIR defined above

The configuration file is a simple .json file and contains the basic observational setup which are loosely grouped into the following parameter groups:

• general parameters (paths, output options, etc.)
• measurement set parameters (pre-pended with "ms_")
• imaging parameters (pre-pended with "im_")
• tropospheric parameters (pre-pended with a "trop_")
• antenna pointing error parameters (pre-pended "pointing_")

The following two important paths are specified in the configuration file:

• "ms_antenna_table": input ANTENNA table for chosen array (CASA format)
• "station_info" input station-specific information (SEFDs, station names)
• imaging parameters (pre-pended with "im_")
• antenna pointing error parameters (pre-pended "pointing_")

Commonly encountered problems

1. If MeqSilhouette cannot find aatm, add the following paths to the following environment variables:

export LD_LIBRARY_PATH=/path/to/aatm-0.5/lib:$LD_LIBRARY_PATH

export PATH=/path/to/aatm-0.5/bin:$PATH

Additional links

• Measurement Set structure and definition link