CASA on the fringe -- Development of VLBI processing capabilities for CASA

Abstract

New functionality to process Very Long Baseline Interferometry (VLBI) data has been implemented in the CASA package. This includes two new tasks to handle fringe fitting and VLBI-specific amplitude calibration steps. Existing tasks have been adjusted to handle VLBI visibility data and calibration meta-data properly. With these updates, it is now possible to process VLBI continuum and spectral line observations in CASA. This article describes the development and implementation, and presents an outline for the workflow when calibrating European VLBI Network or Very Long Baseline Array data in CASA. Though the CASA VLBI functionality has already been vetted extensively as part of the Event Horizon Telescope data processing, in this paper we compare results for the same dataset processed in CASA and AIPS. We find identical results for the two packages and conclude that CASA in some cases performs better, though it cannot match AIPS for single-core processing time. The new functionality in CASA allows for easy development of pipelines or Jupyter notebooks, and thus contributes to raising VLBI data processing to present day standards for accessibility, reproducibility, and reusability.

PASP in press, joint submission with the CASA reference paper; 12 pages, 5 figures

References in corpus (9)

• CASA, the Common Astronomy Software Applications for Radio Astronomy
• First M87 Event Horizon Telescope Results. II. Array and Instrumentation
• First M87 Event Horizon Telescope Results. III. Data Processing and Calibration
• First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multi-wavelength Observations, Data Processing, and Calibration
• DiFX: A software correlator for very long baseline interferometry using multi-processor computing environments
• Event Horizon Telescope observations of the jet launching and collimation in Centaurus A
• Polarization calibration techniques for new-generation VLBI
• MeqSilhouette : A mm-VLBI observation and signal corruption simulator
• MeqSilhouette v2: Spectrally-resolved polarimetric synthetic data generation for the Event Horizon Telescope

Cited by in corpus (7)

• Radio jet precession in M81*
• Polarimetric Geometric Modeling for mm-VLBI Observations of Black Holes
• A Radio Study of Persistent Radio Sources in Nearby Dwarf Galaxies: Implications for Fast Radio Bursts
• An Interferometric SETI Observation of Kepler-111 b
• The early radio afterglow of short GRB 230217A
• Deep learning inference with the Event Horizon Telescope I. Calibration improvements and a comprehensive synthetic data library
• Towards an astronomical use of new-generation geodetic observations. I. From the correlator to full-polarization images