|
|
| (151 intermediate revisions by 9 users not shown) |
| Line 1: |
Line 1: |
| [[Category:EVLA]][[Category:Imaging]] | | #REDIRECT [[EVLA Wide-Band Wide-Field Imaging: G55.7 3.4-CASA4.4]] |
| | |
| <!--
| |
| == BEFORE YOU START==
| |
| Make sure you have done the steps described at [[Initial_instructions_for_2010| the initial instructions for the 2010 Synthesis Workshop Tutorials]].
| |
| -->
| |
| | |
| == Overview ==
| |
| | |
| 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.
| |
| | |
| 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?ARCHIVE_VOLUME=AB1345_sb1800808_1.55431.004049953706&OBS_BANDS=ALL&TELESCOPE=EVLA&OBS_MODE=ALL&CORR_MODE=ALL&TELESCOPE_CONFIG=ALL&OBS_POLAR=ALL&SUBARRAY=ALL&OBSFREQ1=&DATATYPE=ALL&OBSBW1=&ARCHFORMAT=ALL&SUBMIT=Submit+Query 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 <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>
| |
| | |
| </pre>
| |
| | |
| == A priori calibration and flagging ==
| |
| | |
| Before we proceed with further processing, we should check the observation log to see if there were any issues noted during the run that need to be addressed. The log can be found at
| |
| | |
| === 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 ===
| |
