Changes between Version 22 and Version 23 of Notes/ExampleReduction


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Timestamp:
03/31/09 15:32:18 (15 years ago)
Author:
JamieStevens
Comment:

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  • Notes/ExampleReduction

    v22 v23  
    321321images, and this is because the primary beam of the antenna gets smaller with increasing frequency.
    322322
     323So we can compare these results with the other methods of imaging, we make some rough measurements of flux of each source.
     324According to NED, SUMSS J054003-663939 has a flux of 1.27 mJy at 843 MHz, and SUMSS J054125-664307 has a flux of 0.94 mJy
     325at 843 MHz.
     326
     327We get our fluxes using kvis, by taking the sum of the flux in 9 pixels (3x3) centred on the brightest pixel of each source.
     328This should be approximately 1 beam, so we can normalise the flux in the images. The table below shows how the flux of the
     329sources varies with frequency. Note that at a frequency of 5692 MHz the sources are right on the edge of the image, so
     330no measurements are done at frequencies higher than this.
     331
     332|| Central Freq (MHz) || J054003-663939 || J054125-664307 ||
     333|| 4540               || 1.0 +- 0.2     || n/a            ||
     334|| 4668               || 1.0 +- 0.2     || 1.0 +- 0.2     ||
     335|| 4796               || 1.1 +- 0.3     || 1.0 +- 0.3     ||
     336|| 4924               || 1.1 +- 0.4     || 0.8 +- 0.4     ||
     337|| 5052               || n/a            || 1.3 +- 0.3     ||
     338|| 5180               || 1.0 +- 0.4     || n/a            ||
     339|| 5308               || 1.2 +- 0.4     || 1.2 +- 0.4     ||
     340|| 5436               || 1.6 +- 0.3     || 1.2 +- 0.3     ||
     341|| 5692               || 1.2 +- 0.4     || 0.9 +- 0.4     ||
     342
     343The sources don't appear to vary in flux much with frequency, at least within the errors of measurement. That would
     344suggest that using mfclean instead of clean might not produce a different result.