Karl G. Jansky VLA Tutorials: Difference between revisions

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'''Disclaimer: The tutorials presented here are provided as guidelines to assist users in familiarizing themselves with VLA data reduction in [https://casa.nrao.edu/ CASA].  The tutorials offer examples for common general-use cases such as spectral line, continuum, linear polarization, and mosaicking.  However, the results achieved in these tutorials are specific to the data sets herein. The flexibility of the VLA is such that the techniques presented here may not apply equally to every individual VLA data set, especially if the type of observations, quality of data, or imaging analysis are particularly different or complicated. More details about CASA and its tasks and tools are available in the [https://casa.nrao.edu/casadocs Online CASA Documentation]. Further assistance with VLA data reduction is available through the [https://help.nrao.edu/ NRAO HelpDesk].'''
Disclaimer: These tutorials provide guidelines to help users become familiar with VLA data reduction in [https://casa.nrao.edu/ CASA].  They offer examples for common general-use cases such as spectral line, continuum, linear polarization, and mosaicking.  However, the results demonstrated here are specific to the given data sets. The VLA is an extremely flexible instrument, and the techniques presented here may not apply equally to every individual VLA data set, especially if the type of observations, quality of data, or imaging analysis are particularly different or complicated. More details about CASA and its tasks and tools are available in the [https://casa.nrao.edu/casadocs Online CASA Documentation]. Further assistance with VLA data reduction is available through the [https://help.nrao.edu/ NRAO HelpDesk].
 
''For data reduction of pre-EVLA upgrade VLA data, we provide separate, [https://casaguides.nrao.edu/index.php/Pre-upgrade_VLA_Tutorials pre-upgrade VLA data reduction tutorials]''
 
 


== Introduction ==
== Introduction ==


The Karl G. Jansky Very Large Array (VLA) Tutorials are meant to guide the observer through some common types of data analysis, using example datasets, and including explanations of the individual steps. These analyses will be broadly applicable to many VLA data sets.  
The Karl G. Jansky Very Large Array (VLA) Tutorials are meant to guide the observer through some common types of data analysis, using example datasets, and including explanations of the individual steps. These analyses will be broadly applicable to many VLA data sets.  


If you are new to CASA, you may start with <h3>[https://casaguides.nrao.edu/index.php?title=Getting_Started_in_CASA Getting Started in CASA]</h3>
If you are new to CASA, you may start with <h3>[https://casaguides.nrao.edu/index.php?title=Getting_Started_in_CASA Getting Started in CASA]</h3>
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=== Carbon Star IRC+10216: high frequency (36GHz), spectral line data reduction  ===
=== High frequency (36GHz), spectral line data reduction: Carbon Star IRC+10216 ===
<blockquote>
<blockquote>
* [http://casaguides.nrao.edu/index.php?title=VLA_high_frequency_Spectral_Line_tutorial_-_IRC%2B10216 IRC+10216 Tutorial] (CASA 5.0.0)   
* [http://casaguides.nrao.edu/index.php?title=VLA_high_frequency_Spectral_Line_tutorial_-_IRC%2B10216 IRC+10216 Tutorial] (CASA 5.4.0)   


* This tutorial requires to download a dataset <font color=green>1.1GB</font> in size
* This tutorial requires to download a dataset <font color=green>1.1GB</font> in size
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</blockquote>
</blockquote>


=== Supernova Remnant 3C391: 6cm Polarimetry and Continuum Imaging, Mosaicking ===
=== 6cm Polarimetry and Continuum Imaging, Mosaicking: Supernova Remnant 3C391 ===
<blockquote>
<blockquote>
* [http://casaguides.nrao.edu/index.php?title=VLA_Continuum_Tutorial_3C391 3C391 Tutorial] (CASA 5.0.0)  
* [http://casaguides.nrao.edu/index.php?title=VLA_Continuum_Tutorial_3C391 3C391 Tutorial] (CASA 5.4.0)  


* This tutorial requires to download a dataset <font color=orange>3.1GB</font> in size
* This tutorial requires to download a dataset <font color=orange>3.1GB</font> in size


Calibrate VLA full polarization data, image a mosaic of the region in full Stokes and create a spectral index map.  Includes:
Calibrate VLA full polarization data, image a mosaic of the region in Stokes I.  Includes:
* Inspecting data; basic flagging  
* Inspecting data; basic flagging  
* Calibration
* Calibration
* Image Analysis and Manipulation
* Image Analysis
* Polarization Imaging
* Spectral Index imaging
* Self-calibration  
* Self-calibration  
</blockquote>
</blockquote>


=== 3C129 P-band continuum imaging data reduction tutorial ===
=== P-band continuum imaging data reduction tutorial: 3C129  ===
<blockquote>
<blockquote>
* [https://casaguides.nrao.edu/index.php/VLA_Radio_galaxy_3C_129:_P-band_continuum_tutorial 3C129 P-band Tutorial] (CASA 5.0.0)
* [https://casaguides.nrao.edu/index.php/VLA_Radio_galaxy_3C_129:_P-band_continuum_tutorial 3C129 P-band Tutorial] (CASA 5.4.0)


* This tutorial requires to download a dataset <font color=red>26GB</font> in size  
* This tutorial requires to download a dataset <font color=red>26GB</font> in size  
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* Widefield imaging  
* Widefield imaging  
</blockquote>
</blockquote>


=== P-band spectroscopy tutorial: HI 21cm absorption in MG0414+0534 at z=2.64 ===
=== P-band spectroscopy tutorial: HI 21cm absorption in MG0414+0534 at z=2.64 ===
<blockquote>
<blockquote>
* [https://casaguides.nrao.edu/index.php/MG0414+0534_P-band_Spectral_Line_Tutorial MG0414+0534 P-band Spectral Line Tutorial] (CASA 5.0.0)
* [https://casaguides.nrao.edu/index.php/MG0414+0534_P-band_Spectral_Line_Tutorial MG0414+0534 P-band Spectral Line Tutorial] (CASA 5.4.0)


* This tutorial is based on an archival data-set of 142 Gb in size, but we will extract only a <font color=red>15Gb</font> portion of this data-set to work on.  
* This tutorial is based on an archival data-set of 142 Gb in size, but we will extract only a <font color=red>15Gb</font> portion of this data-set to work on.  
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<blockquote>
<blockquote>
* [http://casaguides.nrao.edu/index.php/VLA_CASA_Flagging Topical Guide: Flagging VLA Data] (CASA 5.0.0)
* [http://casaguides.nrao.edu/index.php/VLA_CASA_Flagging Topical Guide: Flagging VLA Data] (CASA 5.4.0)


* This tutorial requires to download a dataset <font color=green>4.9GB</font> in size
* This tutorial requires to download a dataset <font color=green>4.9GB</font> in size
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* Online Flags (shadowing, zeroes, quacking, flagmanager, Hanning smoothing)
* Online Flags (shadowing, zeroes, quacking, flagmanager, Hanning smoothing)
* Automatic RFI excision (TFCrop, RFlag)
* Automatic RFI excision (TFCrop, RFlag)
* Interactive Flagging
* Interactive Flagging (plotms, msview)
* Flagging Summary & Report
* Flagging Summary & Report
</blockquote>
</blockquote>
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<blockquote>
<blockquote>
* [http://casaguides.nrao.edu/index.php/VLA_CASA_Imaging Topical Guide: Imaging VLA Data] (CASA 5.0.0)
* [http://casaguides.nrao.edu/index.php/VLA_CASA_Imaging Topical Guide: Imaging VLA Data] (CASA 5.4.0)


* This tutorial requires to download a dataset <font color=green>1.2GB</font> in size
* This tutorial requires to download a dataset <font color=green>1.2GB</font> in size
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* Image Header, Image Conversion
* Image Header, Image Conversion
</blockquote>
</blockquote>


=== VLA Multi-Configuration Data Combination ===
=== VLA Multi-Configuration Data Combination ===


<blockquote>
<blockquote>
* [http://casaguides.nrao.edu/index.php/VLA_Data_Combination Topical Guide: VLA Data Combination Guide] (CASA 5.0.0)  
* [http://casaguides.nrao.edu/index.php/VLA_Data_Combination Topical Guide: VLA Data Combination Guide] (CASA 5.4.0)  
* This tutorial requires to download a dataset <font color=green>1.4GB</font> in size
* This tutorial requires to download a dataset <font color=green>1.4GB</font> in size


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<blockquote>
<blockquote>
* [http://casaguides.nrao.edu/index.php/VLA_CASA_Bandpass_Slope Topical Guide: Correcting for a Spectral Index in Bandpass Calibration] (CASA 5.0.0)
* [http://casaguides.nrao.edu/index.php/VLA_CASA_Bandpass_Slope Topical Guide: Correcting for a Spectral Index in Bandpass Calibration] (CASA 5.4.0)
* This tutorial requires to download a dataset <font color=green>3.4GB</font> in size
* This tutorial requires to download a dataset <font color=green>3.4GB</font> in size


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== VLA CASA Pipeline Guide ==
== VLA CASA Simulation Guide ==


<blockquote>
<blockquote>
* [http://casaguides.nrao.edu/index.php/VLA_CASA_Pipeline VLA CASA Pipeline Guide] (CASA 4.7.2)
* [https://casaguides.nrao.edu/index.php/Protoplanetary_Disk_Simulation_-_VLA VLA Protoplanetary Disk Simulation Guide] (CASA 5.4.0)
* This tutorial does not require any download.  
* This tutorial does not require any download.  


The VLA CASA Pipeline Guide provides an example of a  VLA CASA pipeline run. Whereas the [https://science.nrao.edu/facilities/vla/data-processing/pipeline VLA Pipeline Web Page] describes the pipeline structure, requirements, execution options including restoration, pipeline output products, and pipeline modifications, this CASA guide is a detailed walkthrough of the weblog and provides interpretations of pipeline plots and tables.  
The VLA Protoplanetary Disk Simulation Guide shows examples on how to simulate VLA data based on model images. The tutorial will explain the main simulation tools, apply different parameters to simulations, and compares the results to the VLA exposure calculator.  
</blockquote>
</blockquote>


== VLA CASA Pipeline Guide ==


<blockquote>
* [http://casaguides.nrao.edu/index.php/VLA_CASA_Pipeline VLA CASA Pipeline Guide] (CASA 5.4.1)
* This tutorial does not require any download.
The VLA CASA Pipeline Guide provides an example of a  VLA CASA pipeline run. Whereas the [https://science.nrao.edu/facilities/vla/data-processing/pipeline VLA Pipeline Web Page] describes the pipeline structure, requirements, execution options including restoration, pipeline output products, and pipeline modifications, this CASA guide is a detailed walkthrough of the weblog and provides interpretations of pipeline plots, tables, and Quality Assurance (QA) metrics.
</blockquote>


== CASA Guide Versions ==
== CASA Guide Versions ==
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In addition to the most recent VLA casa guides, below we also provide links to older versions of the VLA CASA guides. Note that some graphs and links may be outdated, or, in some cases, actually point to the current CASA version as content was refreshed. For older CASA documentation, we refer to the links on [https://casa.nrao.edu/previous_casa.shtml Previous CASA Versions] on the [https://casa.nrao.edu CASA home page].
In addition to the most recent VLA casa guides, below we also provide links to older versions of the VLA CASA guides. Note that some graphs and links may be outdated, or, in some cases, actually point to the current CASA version as content was refreshed. For older CASA documentation, we refer to the links on [https://casa.nrao.edu/previous_casa.shtml Previous CASA Versions] on the [https://casa.nrao.edu CASA home page].


=== CASA 5.0 versions ===
=== CASA 5.4.0 / 5.4.1 versions ===
* [https://casaguides.nrao.edu/index.php/VLA_high_frequency_Spectral_Line_tutorial_-_IRC%2B10216-CASA5.4.0 IRC+10216 Tutorial (CASA 5.4.0)]
 
* [https://casaguides.nrao.edu/index.php/VLA_Continuum_Tutorial_3C391-CASA5.4.0 3C391 Continuum Tutorial (CASA 5.4.0)]
 
* [https://casaguides.nrao.edu/index.php/VLA_Radio_galaxy_3C_129:_P-band_continuum_tutorial-CASA5.4.0 3C129 P-band Tutorial (CASA 5.4.0)]
 
* [https://casaguides.nrao.edu/index.php/MG0414%2B0534_P-band_Spectral_Line_Tutorial_-_CASA_5.4.0 MG0414+0534 P-band Spectral Line Tutorial (CASA 5.4.0)]
 
* [https://casaguides.nrao.edu/index.php/VLA_CASA_Flagging-CASA5.4.0 Topical Guide: Flagging VLA Data (CASA 5.4.0)]
 
* [https://casaguides.nrao.edu/index.php/VLA_CASA_Imaging-CASA5.4.0 Topical Guide: Imaging VLA Data (CASA 5.4.0)]
 
* [https://casaguides.nrao.edu/index.php/VLA_Data_Combination-CASA5.4.0 Topical Guide: VLA Multi-Configuration Data Combination (CASA 5.4.0)]
 
* [https://casaguides.nrao.edu/index.php/VLA_CASA_Bandpass_Slope-CASA5.4.0 Topical Guide: Correcting for a Spectral Index in Bandpass Calibration (CASA 5.4.0)]
 
* [https://casaguides.nrao.edu/index.php/Protoplanetary_Disk_Simulation_-_VLA-CASA5.4.0 Protoplanetary Disk Simulation - VLA (CASA 5.4.0)]
 
* [http://casaguides.nrao.edu/index.php/VLA_CASA_Pipeline-CASA5.4.1 VLA CASA Pipeline Guide (CASA 5.4.1)]
 
 
 
<!-- === CASA 5.3 versions ===
* [https://casaguides.nrao.edu/index.php/VLA_Radio_galaxy_3C_129:_P-band_continuum_tutorial-CASA5.3.0 C129 P-band Tutorial (CASA 5.3.0)]
-->
 
=== CASA 5.0 / 5.1.2 versions ===


* [http://casaguides.nrao.edu/index.php?title=VLA_high_frequency_Spectral_Line_tutorial_-_IRC%2B10216-CASA5.0.0 IRC+10216 Tutorial (CASA5.0.0)]   
* [http://casaguides.nrao.edu/index.php?title=VLA_high_frequency_Spectral_Line_tutorial_-_IRC%2B10216-CASA5.0.0 IRC+10216 Tutorial (CASA5.0.0)]   
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* [https://casaguides.nrao.edu/index.php/VLA_CASA_Bandpass_Slope-CASA5.0.0 Topical Guide: Correcting for a Spectral Index in Bandpass Calibration (CASA 5.0.0)]
* [https://casaguides.nrao.edu/index.php/VLA_CASA_Bandpass_Slope-CASA5.0.0 Topical Guide: Correcting for a Spectral Index in Bandpass Calibration (CASA 5.0.0)]
* [http://casaguides.nrao.edu/index.php/VLA_CASA_Pipeline-CASA5.1.2 VLA CASA Pipeline Guide (CASA 5.1.2)]


=== CASA 4.7 versions ===
=== CASA 4.7 versions ===

Revision as of 14:41, 26 December 2018

Disclaimer: These tutorials provide guidelines to help users become familiar with VLA data reduction in CASA. They offer examples for common general-use cases such as spectral line, continuum, linear polarization, and mosaicking. However, the results demonstrated here are specific to the given data sets. The VLA is an extremely flexible instrument, and the techniques presented here may not apply equally to every individual VLA data set, especially if the type of observations, quality of data, or imaging analysis are particularly different or complicated. More details about CASA and its tasks and tools are available in the Online CASA Documentation. Further assistance with VLA data reduction is available through the NRAO HelpDesk.

For data reduction of pre-EVLA upgrade VLA data, we provide separate, pre-upgrade VLA data reduction tutorials


Introduction

The Karl G. Jansky Very Large Array (VLA) Tutorials are meant to guide the observer through some common types of data analysis, using example datasets, and including explanations of the individual steps. These analyses will be broadly applicable to many VLA data sets.


If you are new to CASA, you may start with

Getting Started in CASA



VLA Data Reduction Tutorials

High frequency (36GHz), spectral line data reduction: Carbon Star IRC+10216

  • This tutorial requires to download a dataset 1.1GB in size

Calibrate and make image cubes of the line emission from this asymptotic giant branch star. This is a high-frequency VLA dataset. Includes:

  • Inspecting data; basic flagging & calibration
  • Subtracting continuum emission
  • Imaging the spectral lines
  • Imaging the continuum
  • Image analysis
  • Self-calibration

6cm Polarimetry and Continuum Imaging, Mosaicking: Supernova Remnant 3C391

  • This tutorial requires to download a dataset 3.1GB in size

Calibrate VLA full polarization data, image a mosaic of the region in Stokes I. Includes:

  • Inspecting data; basic flagging
  • Calibration
  • Image Analysis
  • Self-calibration

P-band continuum imaging data reduction tutorial: 3C129

  • This tutorial requires to download a dataset 26GB in size

This low frequency VLA tutorial for the observation of radio galaxy 3C 129 focuses on low frequency wide-fractional-bandwidth data in the sub GHz regime and demonstrates multi-frequency synthesis imaging with w-projection. This includes:

  • Basic flagging and evaluation
  • Automatic RFI Excision
  • Ionospheric Calibration
  • Self - Calibration
  • Widefield imaging


P-band spectroscopy tutorial: HI 21cm absorption in MG0414+0534 at z=2.64

  • This tutorial is based on an archival data-set of 142 Gb in size, but we will extract only a 15Gb portion of this data-set to work on.

This VLA P-band tutorial is aimed at calibrating and making an image cube of line-emission centered on 390.6 MHz. It includes:

  • P-band spectral-line observing strategies
  • Basic flagging options
  • Low-frequency calibration and self-calibration
  • Spectral-line imaging

VLA Topical Guides

Flagging VLA Data in CASA

  • This tutorial requires to download a dataset 4.9GB in size

This tutorial describes different flagging techniques, including:

  • Identifying Problematic Antennas from the Operator Logs
  • Online Flags (shadowing, zeroes, quacking, flagmanager, Hanning smoothing)
  • Automatic RFI excision (TFCrop, RFlag)
  • Interactive Flagging (plotms, msview)
  • Flagging Summary & Report

Imaging VLA Data in CASA

  • This tutorial requires to download a dataset 1.2GB in size

The Imaging topical guide shows annotated examples of different imaging techniques that are applicable to different science applications. This tutorial includes:

  • An Introduction to the CLEAN algorithm, data and imaging weights, primary and synthesized beams
  • Clean Output Images
  • Dirty Image, Regular CLEAN & RMS Noise, CLEAN with different Weights
  • Multi-Scale CLEAN
  • Multi-Scale, Wide-Field CLEAN (w-projection)
  • Multi-Scale, Multi-Term Frequency Synthesis
  • Multi-Scale, Multi-Term Frequency, Widefield CLEAN
  • Imaging Outlier Fields
  • Primary Beam Correction
  • Imaging Spectral Cubes, Beam per Plane
  • Image Header, Image Conversion

VLA Multi-Configuration Data Combination

The VLA Data Combination Tutorial provides guidance on the combination of multi-configuration VLA data sets (in this case VLA A, B and C configurations). The data are re-weighted in two different ways, combined, and imaged. The guide also explains how to remove a time variable source from the data before combination.

Correcting for a Spectral Index in Bandpass Calibration

This tutorial explains how to obtain a bandpass solution when the bandpass calibrator is a source with an unknown spectral index. This is typically encountered at high frequency observations, where the standard VLA flux density calibrators are too weak for high signal-to-noise bandpass solutions.



VLA CASA Simulation Guide

The VLA Protoplanetary Disk Simulation Guide shows examples on how to simulate VLA data based on model images. The tutorial will explain the main simulation tools, apply different parameters to simulations, and compares the results to the VLA exposure calculator.

VLA CASA Pipeline Guide

The VLA CASA Pipeline Guide provides an example of a VLA CASA pipeline run. Whereas the VLA Pipeline Web Page describes the pipeline structure, requirements, execution options including restoration, pipeline output products, and pipeline modifications, this CASA guide is a detailed walkthrough of the weblog and provides interpretations of pipeline plots, tables, and Quality Assurance (QA) metrics.

CASA Guide Versions

In addition to the most recent VLA casa guides, below we also provide links to older versions of the VLA CASA guides. Note that some graphs and links may be outdated, or, in some cases, actually point to the current CASA version as content was refreshed. For older CASA documentation, we refer to the links on Previous CASA Versions on the CASA home page.

CASA 5.4.0 / 5.4.1 versions



CASA 5.0 / 5.1.2 versions


CASA 4.7 versions

CASA 4.6 versions

CASA 4.5 versions

CASA 4.4 versions

CASA 4.3 versions

CASA 4.2 versions

CASA 4.1 versions

CASA 3.4 versions

CASA 3.3 versions