3.iii: Imaging the residuals

Logged on 07/10/2009 12:43:14 PM

Once this has finished we can image the residuals. Click the 'TDL Exec' button and expand the 'Make an image from this MS' menu.

A critical option here is that we image the CORRECTED_DATA column, as this is where MeqTrees wrote the source-subtracted visibilities. The original DATA column will be left untouched.

Average all the channels, and let's image our usual 30 arcminute field. Click 'make a dirty image' and it should return something similar to the file in the data products below.

What are we seeing here?

Remember when this simulation was generated we added the slowly varying receiver gain errors. The residual structure here is the result of these errors, and you can see the levels at which this pollutes the map in the histogram. All we have done so far is subtract a model visibility set consistent with a 10 Jy unpolarized source at the field centre.

A more sensible thing to do is to do some calibration and try to solve for those receiver gain errors.

Data products

SSSC1_WSRT.MS.CORRECTED_DATA.channel.1ch.fits (header)

0-full.png0-hist-full.png
0-hist-zoom.png
data range:-0.0280808,0.0285035
size:1x1x512x512
mean:4.44035e-05
sigma:0.00678466
clipping:95%
clip range:-0.0159793,0.0121471