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| [[Category:EVLA]][[Category:Imaging]] | | #REDIRECT [[EVLA Wide-Band Wide-Field Imaging: G55.7 3.4-CASA4.4]] |
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| <!--
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| == BEFORE YOU START==
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| Make sure you have done the steps described at [[Initial_instructions_for_2010| the initial instructions for the 2010 Synthesis Workshop Tutorials]].
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| -->
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| == Overview ==
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| This CASA Guide describes the imaging of the supernova remnant [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=G55.7+3.4&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id 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.
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| 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 [[https://archive.nrao.edu/archive/ArchiveQuery?PROJECT_CODE= here]]; note that it is 170 GB in raw form.
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| 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.
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| [Instructions on locating data at the workshop... and from outside the workshop.]
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| == Preliminary data evaluation ==
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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.
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| As a first step, use {{listobs}} to have a look at the MS:
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| <source lang="python">
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| # In CASA
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| listobs('G55.7+3.4_10s.ms')
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| </source>
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| The logger output will look like this:
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| <pre>
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| == A priori calibration and flagging ==
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| === Antenna position correction ===
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| === Flagging non-operational antennas ===
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| == Automatic RFI excision ==
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| === Hanning-smoothing data ===
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| === Using phase calibration source for preliminary bandpass calibration ===
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| === Running testautoflag ===
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| === Evaluating results & manual flagging ===
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| Flagging lowest edge of SPW 0 ...
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| == Calibrating data ==
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| === Clearing previous calibration ===
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| === Setting flux scale ===
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| === Bandpass calibration ===
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| === Gain calibration ===
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| === Flux scaling gain solutions ===
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| === Applying calibration ===
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| === Plotting calibrated data ===
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| == Imaging ==
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| === Splitting out target data ===
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| === Multi-scale clean ===
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| === Multi-scale, multi-frequency synthesis ===
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| === Multi-scale, wide-field clean ===
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| === Multi-scale, multi-frequency, wide-field clean ===
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