Name: CASA VLBI Workshop 2023
Start: 2023-06-05T09:00:00+02:00
End: 2023-06-09T18:00:00+02:00
Location: JIVE

CASA VLBI Workshop 2023

from Monday, 5 June 2023 (09:00) to Friday, 9 June 2023 (18:00)

Monday, 5 June 2023

11:30 Registration Open
Registration Open
11:30 - 12:30

12:30 Lunch
Lunch
12:30 - 13:30

13:30 Start: welcome
Start: welcome
13:30 - 13:45
13:45 Lecture 1 Introduction to interferometry & calibration - George Moellenbrock
Lecture 1 Introduction to interferometry & calibration
- George Moellenbrock
13:45 - 14:45
14:45 Lecture 2 Introduction to CASA - Bjorn Emonts
Lecture 2 Introduction to CASA
- Bjorn Emonts
14:45 - 15:45
15:45 Break
Break
15:45 - 16:30
16:30 Lecture 3 Introduction to CARTA - Kuo-Song Wang
Lecture 3 Introduction to CARTA
- Kuo-Song Wang
16:30 - 17:30
CARTA, Cube Analysis and Rendering Tool for Astronomy, is a new image visualization and analysis tool designed for ALMA, VLA, and SKA pathfinders. Its focus is the support of large image cubes (several hundred GB to a few TB). In this tutorial, we will provide some basic information about the CARTA development project, as well as basic usages of CARTA for continuum, spectral line, and polarization images. Lecture slides and image data for hands-on exercise will be provided.
Tuesday, 6 June 2023

09:00 Lecture 4 VLBI instruments and data access
Lecture 4 VLBI instruments and data access
09:00 - 10:00
* 9:00 - 9:15 EVN -- Zsolt Paragi * 9:15 - 9:30 VLBA -- George Moellenbrock * 9:30 - 9:45 e-MERLIN -- David Williams * 9:45 - 10:00 LOFAR -- Emanuela Orru'
10:00 Lecture 5 Amplitude calibration in CASA - Mark Kettenis
Lecture 5 Amplitude calibration in CASA
- Mark Kettenis
10:00 - 11:00
One of the major differences between calibration of connected-element interferometry data (VLA, ALMA) and calibration of VLBI data is how amplitude calibration is done. This lecture will discuss how amplitude calibration works for VLBI, how to obtain the relevant metadata in a form that can be used with CASA and the CASA tasks involved in creating and applying the amplitude calibration for VLBI data.
11:00 Break
Break
11:00 - 11:45
11:45 Lecture 6 Fringe fitting and other VLBI specifics in CASA - Des Small
Lecture 6 Fringe fitting and other VLBI specifics in CASA
- Des Small
11:45 - 12:45
When combining signals from separate antennas to do interferometry, we focus our observation on a phase centre by applying appropriate delays based on a geometric and atmospheric model. However, the atmosphere isn't perfectly predictable, and signal chains may also introduce delays. In order to be able to average down data for imaging and other analysis we need to calibrate out residual delays by fringe fitting. Building on the Radio Interferometry Measurement Equation, this lecture will explain the theory and the practice of fringefitting in CASA.
12:45 Lunch
Lunch
12:45 - 14:00
14:00 Data processing A : Introduction to EVN Jupyter-CASA notebooks - Ilse van Bemmel
Data processing A : Introduction to EVN Jupyter-CASA notebooks
- Ilse van Bemmel
14:00 - 15:30
15:30 Break
Break
15:30 - 16:00

16:00 Data processing B
Data processing B
16:00 - 17:30
Wednesday, 7 June 2023
09:00 Lecture 7 Imaging - Cristiana Spingola
Lecture 7 Imaging
- Cristiana Spingola
09:00 - 10:00
The laborious task of “imaging” consists in the process of transforming the interferometer natural measurements (visibilities) into images. This tutorial will cover the basic concepts, and how to use CASA for imaging radio interferometric data and calculate statistics on them.
10:00 Lecture 8 Self-calibration - Javier Moldon
Lecture 8 Self-calibration
- Javier Moldon
10:00 - 11:00
Self-calibration is a powerful but delicate technique in interferometry used to improve the calibration of a data set when a moderately bright source is present in the target field, which can boost the dynamic range of target images. It consists of refining the phases and amplitudes of visibilities using a model of the same field we aim to image. We will see why this technique is needed and when it is feasible, and we will explain how to use CASA to obtain and apply self-calibration to VLBI data.
11:00 Break
Break
11:00 - 11:45
11:45 Lecture 9 Spectral line processing - Olga Bayandina
Lecture 9 Spectral line processing
- Olga Bayandina
11:45 - 12:45
Spectral line data reduction largely follows the logic and steps of continuum data reduction. However, there are a few specific deviations that need to be taken into account. For instance, narrow and bright maser lines could be flagged out, and broad absorption lines could affect bandpass calibration if not taken special care of. More dos and don'ts of spectral line processing in this lecture
12:45 Lunch & Group picture
Lunch & Group picture
12:45 - 14:00

14:00 Data processing C
Data processing C
14:00 - 15:30

15:30 Break
Break
15:30 - 16:00

16:00 Data processing D
Data processing D
16:00 - 17:30

18:00 Social Event
Social Event
18:00 - 21:00
Thursday, 8 June 2023
09:00 Lecture 10 Polarization calibration - Ivan Marti-Vidal
Lecture 10 Polarization calibration
- Ivan Marti-Vidal
09:00 - 10:00
We will review the basic concepts of polarimetry, as well as the astrophysical exploitation of polarization observations, with emphasis in the radio/mm window and VLBI. Then, we will study how polarization is observed and calibrated in radio astronomical interferometry, with emphasis on the peculiarities of VLBI. Finally, we will learn the use, tips and tricks, of VLBI polarimetry calibration software based on CASA.
10:00 Lecture 11 Wide-field data processing - Jack Radcliffe
Lecture 11 Wide-field data processing
- Jack Radcliffe
10:00 - 11:00
Surveys using the whole field-of-view of VLBI arrays are now possible, permitting sensitive investigations of multiple sources within a single observation. This mode has already borne fruit, with investigations into many different phenomena such as active galactic nuclei, supernovae, and gravitational lenses, across degrees of the sky. In this lecture I shall outline the differences between standard VLBI observing and wide-field VLBI. I will focus on how we deal with the multiple phase centres, and the extra direction-dependent effects, such as the atmosphere and primary beams. I will conclude by presenting the VLBI Pipeline (VPIPE), a CASA-based, highly parallelised, pipeline that can automatically process wide-field VLBI in a fraction of the observing time.
11:00 Break
Break
11:00 - 11:45
11:45 Lecture 12 rPicard and mm-VLBI - Michael Janssen
Lecture 12 rPicard and mm-VLBI
- Michael Janssen
11:45 - 12:45
High-frequency VLBI instruments, such as the EHT and GMVA, offer the highest angular resolution observations from the ground. To measure the short millimeter wavelengths, excellent weather conditions and telescopes with superb surface accuracies are needed. Hence, mm VLBI observations are typically made with sparse arrays consisting of dishes with small collecting areas. Additionally, short atmospheric coherence times can limit the sensitivity substantially. In this lecture, I will describe how to deal with these difficulties and properly calibrate mm VLBI data, following the steps of the rPICARD pipeline (https://bitbucket.org/M_Janssen/picard). rPICARD is a generic open-source tool, which allows the VLBI community to obtain reproducible results. Next to mm VLBI data sets, rPICARD can also be applied to cm VLBI data, as well as phase-referencing and spectral line experiments.
12:45 Lunch
Lunch
12:45 - 14:00

14:00 Data processing E
Data processing E
14:00 - 15:30

15:30 Break
Break
15:30 - 16:00

16:00 Data processing F
Data processing F
16:00 - 17:30
Friday, 9 June 2023

09:00 Data processing G
Data processing G
09:00 - 10:15

10:15 Break
Break
10:15 - 11:00

11:00 Wrap-up lecture
Wrap-up lecture
11:00 - 12:15

12:15 Final remark
Final remark
12:15 - 12:30

12:30 Lunch
Lunch
12:30 - 13:30