VLBI Tutorials

Tutorials for Very Long Baseline Interferometry

CASA is offering increased VLBI support through a collaboration with the Joint Institute for VLBI ERIC (JIVE).

CASA can be used to process VLBA continuum data, but development and testing are ongoing and NRAO currently recommends using AIPS for all VLBA data. VLBI processing in CASA has been extensively tested with EVN continuum data. Other use cases and telescopes are still being verified. Feedback on results (also successful ones) and missing or optimizing functionality is very welcome at casa_feedback_at_nrao.edu.

For the Event Horizon Telescope (EHT) project, one of three certified pipelines is based on CASA. This 'rPicard' pipeline has since evolved into a generic all-purpose pipeline for VLBI processing. While rPicard is not supported by the CASA team, users can find more information in Janssen et al. (2019).

VLBA CASA tutorials

The following CASA tutorial covers calibrating and imaging a basic phase-referenced VLBA observation.

CASA VLBA tutorial: VLBA Basic Phase-referencing Tutorial (CASA 6.4.0)

In addition to the CASA tutorial, the following document describes the procedure for calibrating VLBA phase-referenced observations with CASA, including self-calibration.

VLBA Data Calibration with CASA: VLBA Scientific Memo #38

VLBA AIPS and CASA Walk-through

This walk-through is meant to assist VLBA users who are familiar with either AIPS or CASA to use the other software package. The walk-though is based on the CASA Basic Phase-referencing tutorial above and uses the same data set. It is not a full tutorial, so it does not contain full details on each step.

AIPS and CASA Walk-through: VLBA AIPS and CASA Walk-through

VLBA AIPS tutorials

While the above tutorial for processing VLBA data in CASA is available, we also include below two AIPS tutorials on this topic.

AIPS tutorial: Simple Self-Calibration

AIPS tutorial: Spectral Lines and Astrometry

EVN CASA tutorials

The below EVN CASA tutorials introduce the CASA environment and touch upon the visualization, calibration and imaging capabilities available, along with the scripting methods so that you can create your own calibration scripts for your own data.

CASA tutorial: EVN Continuum Imaging & Calibration

CASA tutorial: EVN HI Spectral Line

Credits: These CASA tutorials represent publicly available materials developed by scientists from the University of Manchester, the Joint Institute for VLBI ERIC (JIVE), and the University of Pretoria/SARAO through funding from Development in Africa with Radio Astronomy (DARA). The materials are based upon a workshop developed by Anita Richards (University of Manchester) in 2016. The subsequent update has been conducted by Jack Radcliffe (SARAO/ University of Pretoria), which has been influenced by Des Small's (JIVE) EVN CASA tutorial, based on AIPS material provided by Minnie Mao. When starting with archival EVN observations, this EVN CASA tutorial explains the required steps for converting the data into a Measurement Set (in the EVN Continuum tutorial these steps are not complete). Thanks to Ilse van Bemmel (JIVE) for making these materials available for the CASA Guides.