Skills Output

Participants will be able to choose between the HI Analysis and Advanced Calibration/Imaging splinter streams during the workshop. Please consult the Draft Schedule for a view of what the programme may look like.

We intend to focus on the following skills during this two week workshop:

  • Basic Calibration (CASAPY, MIRIAD)
  • A review of the basics of cross and self calibration. This will involve the import, flagging and calibration of several datasets.

  • Advanced Calibration (MeqTrees, Peeling, Solving for DDEs)
  • The astrophysical interpretation of images depends on the image fidelity or dynamic range achieved. Artefacts due to direction dependent effects in the presence of strong sources thus pose a fundamental problem. With this theme we develop a view of the problem based on the Measurement Equation, and we demonstrate how to use different techniques to mitigate the effect of direction dependent effects, thereby leading to high dynamic range images.

  • Imaging
  • With this theme we focus on the challenges and subtleties related to deconvolution and imaging. In particular, we will focus on imaging line emission data, which produces H I line cubes, which are then used for advanced analysis. We will introduce different methods for imaging, including multi-scale multi-frequency clean.

  • Analysis (Source Finding, Moments Analysis, H I source characterisation)
  • The previous step produces continuum images and line cubes. These products will be input to source finding algorithms to extract astronomical source properties, as characterised by the H I line emission. We will also introduce the concept of moments analysis and contrast it with 3D-source fitting. Both methods serve to study the detailed distribution and kinematics of the atomic gas and have their merits and limitations, the knowledge of which is crucial for the scientific interpretation of the results. Finally, other source characterisation techniques such as the determination of asymmetry indicators will be discussed.

  • Working with Sample Datasets
  • It is essential that the participants get familiar with dealing with data. We will provide datasets from a variety of radio telescopes (e.g., WSRT, EVLA/VLA, KAT-7). The datasets will accompany the participants throughout the workshop - at the beginning they will work on the basic editing, inspection and calibration of the data. They will move onto direction dependent calibration, continuum subtraction and line imaging; producing line cubes representing different astrophysical scenario, e.g., single nearby (resolved) galaxies (for moment analyses and kinematic modelling) and many faint, unresolved galaxies (for source finding).