EVLA Wide-Band Wide-Field Imaging: G55.7 3.4: Difference between revisions
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Start CASA by typing <tt>casapy-stable</tt> on the command line. If you have not used CASA before, some helpful tips are available on the [[Getting Started in CASA]] page. | Start CASA by typing <tt>casapy-stable</tt> on the command line. If you have not used CASA before, some helpful tips are available on the [[Getting Started in CASA]] page. | ||
As a first step, use {{listobs}} to have a look at the MS: | |||
<source lang="python"> | |||
# In CASA | |||
listobs('G55.7+3.4_10s.ms') | |||
</source> | |||
The logger output will look like this: | |||
<pre> | |||
== A priori calibration and flagging == | == A priori calibration and flagging == | ||
Revision as of 13:50, 26 August 2011
Overview
This CASA Guide describes the imaging of the supernova remnant G55.7+3.4.. The data were taken on August 23, 2010, in the first D-configuration for which the new wide-band capabilities of the WIDAR correlator were available. The 8-hour-long observation includes all available 1 GHz of bandwidth in L-band, from 1-2 GHz in frequency.
The measurement set (MS) which provides a starting point for this Guide has been imported from the SDM file set and time-averaged to 10 seconds. Both of these options are available from the NRAO data archive, and since this operation can be relatively time-consuming, the imported, time-averaged dataset is being provided. The original data set can be found [here]; note that it is 170 GB in raw form.
Averaging to 10 seconds and the removal of some scans which are not used in this tutorial reduces the size of the data set to around 14 GB; the addition of columns for model and corrected data (known as "scratch columns") returns it to 43 GB, which is the size of the MS which will be used here.
[Instructions on locating data at the workshop... and from outside the workshop.]
Preliminary data evaluation
Start CASA by typing casapy-stable on the command line. If you have not used CASA before, some helpful tips are available on the Getting Started in CASA page.
As a first step, use listobs to have a look at the MS:
# In CASA
listobs('G55.7+3.4_10s.ms')
The logger output will look like this:
A priori calibration and flagging
Antenna position correction
Flagging non-operational antennas
Automatic RFI excision
Hanning-smoothing data
Using phase calibration source for preliminary bandpass calibration
Running testautoflag
Evaluating results & manual flagging
Flagging lowest edge of SPW 0 ...Calibrating data
Clearing previous calibration
Setting flux scale
Bandpass calibration
Gain calibration
Flux scaling gain solutions
Applying calibration
Plotting calibrated data
Imaging
Splitting out target data
Multi-scale clean
Multi-scale, multi-frequency synthesis
Multi-scale, wide-field clean
Multi-scale, multi-frequency, wide-field clean
