simms

simms simulates radio-interferometer observations end to end.

• telsim builds a Measurement Set (MS) from a telescope layout.

• skysim predicts model visibilities from a sky model (ASCII catalogue, FITS image, or WSClean component list) into an existing MS.

• primary-beam exposes the beam machinery on its own: build a beam cube, tag an MS with per-antenna telescope labels, or apply/correct a sky model.

$ simms telsim --telescope kat-7 --startfreq 900MHz --dfreq 1MHz --nchan 64 obs.ms
$ simms skysim --ascii-sky skymodel.txt --column DATA obs.ms

Or chain both steps in one invocation:

$ simms --ms obs.ms --chain \
    telsim --telescope kat-7 --startfreq 900MHz --dfreq 1MHz --nchan 64 \
    skysim --ascii-sky skymodel.txt --column DATA

Getting started

• Installation
  • Requirements
  • From PyPI
  • From GitHub
  • For development
• Quickstart
  • 1. Create an MS
  • 2. Write a sky model
  • 3. Predict visibilities
  • Chain both steps
  • 4. Add noise
  • 5. Add corruptions
  • 6. Use a subarray
  • Where to next

Concepts

• telsim – building a Measurement Set
  • Required inputs
  • Usage
  • Time and frequency specification
  • Subarrays
  • Polarisation
  • Noise and sensitivity
  • Elevation limits
  • Telescope-name column
  • Where to next
• skysim – predicting visibilities
  • Basic usage
  • ASCII sky model schema
  • FITS sky models
  • WSClean component lists
  • Adding to or subtracting from an existing column
  • Time and bandwidth smearing
  • Thermal noise
  • Corruptions
  • Polarisation and polarisation basis
  • Selecting a field or spectral window
  • Chunking large MSs
  • Where to next
• Primary beams and a-terms
  • Where the beam is centred
  • Choosing a beam model
  • Diagonal or full Jones
  • Beams in the FITS-image path
  • Controlling a-term cost
  • The standalone primary-beam tool
  • Examples
• Schemas
  • What an ASCII sky model looks like
  • simms sky model schema
  • PyBDSF Gaussian-list schema mapper (GAUL)
  • PyBDSF source-list schema mapper (SRL)
  • Aegean sky model schema mapper
  • WSClean sky model schema mapper
  • Using a built-in mapper
  • Writing a custom mapper
• Measurement Set conventions
  • Telescope metadata has a single source of truth
  • Pointing centre vs. phase centre
  • POINTING is keyed by (ANTENNA_ID, TIME)
  • Spectral frame must be set
  • STRING columns
  • MOUNT column

Using simms

• Command-line interface
  • Error handling

Reference

• API reference
  • telsim
  • skysim
  • Primary beams
  • Corruptions
  • Utilities

Project

• Contributing
  • Contributing to simms

What’s new

See CHANGES.md for a detailed changelog. Highlights in recent releases include time/bandwidth smearing (--smearing), RIME Jones corruptions (--corruptions), sub-sampled smearing for FITS-image backends (--smearing subsample), and improved CLI error handling.

Indices

• Index

• Module Index

• Search Page