Basic Observing/Data Reduction Commands

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Basic Observing Commands

High-level commands to the antennas, receivers, and correlators are written in python. To execute these commands, you must open a python environment, called a subarray controller (or SAC). The "science1" SAC typically controls the 10-meter and 6-meter antennas and the Spectral Line (SL) correlator. To open the "science1" SAC, type:


The prompt will change to Sci#1[1]:

To get information about a source

To track a source

To tune the receivers

To configure the correlator

To integrate on a source

Basic Data Reduction Commands

  1. Gathering information about your data set.
  2. Baseline calibration.
  3. Linelength calibration.
  4. Displaying your data.
  5. Flagging bad data.
  6. Passband calibration.
  7. Flux calibration.
  8. Gain calibration.
  9. Inverse Fourier Transform.
  10. Deconvolution.
  11. Restore the clean map.
  12. Display maps; analysis.

Getting information about a dataset

listobs vis=test_data.m82.mir

uvlist vis=test_data.m82.mir options=spec

uvindex vis=test_data.m82.mir

Displaying the u,v data

smauvplt vis=test_data.m82.mir axis=time,amp nxy=3,3 line=wide,1,1 device=1/xs options=2pass,source select="source(0841+708),-auto"

smauvplt vis=test_data.m82.mir axis=time,phase yrange=-180,180 nxy=3,3 line=wide,1,1 device=1/xs options=2pass,source select="source(0841+708),-auto"

smauvspec vis=test_data.m82.mir axis=chan,both nxy=2,2 interval=999 device=1/xs select="source(0854+201),-auto"

Calibrating passband variations

uvcal vis=test_data.m82.wides out=test_data.m82.accal options=fxcal (divide cross-correlations by mean of auto-correlations)

uvcat vis=test_data.m82.accal out=test_data.m82.noac select=-auto (write-out data without auto-correlations)

mfcal vis=test_data.m82.noac select="source(0854+201)" interval=1.0 refant=8

uvcat vis=test_data.m82.noac out=test_data.m82.pbcal options=nocal

Use smauvspec to check the results.

Calibrating gain variations

mselfcal vis=test_data.m82.pbcal select="source(0841+708)" interval=17 refant=8 options=amp,noscale,apriori

Use smauvplt to check the results, then uvcat to write-out the calibrated data.

Taking the inverse Fourier transform of the u,v data

invert beam=m82.beam options=systemp,double,mfs,mosaic select="source(M82)" cell=2.0 robust=2.0 imsize=129,129

Displaying the dirty map

cgdisp, type=pix,con slev=a,0.1 levs1=3,4,5,6,7,8,9,10 nxy=1,1 labtyp=arcsec options=full csize=0,0.8,0,0 range=0,0,lin,1 device=1/xs

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