[alma-config] Website patched up, and NEW! hybrid array results

[Steven]

Hello. I believe that I have now got the results I mentioned in the message
below onto my webpages, and also fixed a problem (caused by a crashed
upload) which would have prevented some of the B and C array CLEAN results
from being viewed.

There are also some new results, posted under the guise of "H" resolution
arrays, which makes it a lot easier to churn through my scripts. The H
resolution corresponds to UV data from a 4 hour B resolution track, combined
with the corresponding D resolution snapshot UV data. The snapshot data is
reweighted by a factor of 18.63 through WTMOD and the two sets combined
using DBCON. Results are presented for M51 and CYG for the -70, -23 and +25
declinations.

Results available from...
http://www.heddle97.freeserve.co.uk/ALMA/CLEANIND.HTM
(New results for the "H" resolution, and updated results for B, C and D).

If there are any problems with the webpages, please email me- the site is
now spread over 4 different ISPs and 60MB so there is plenty of scope for
bad links. I hope to move it in its entirety to the ROE site soon, however,
where I can probably provide a zipped version of the whole site for ftp, and
further useful things like that.

I'm off to the bunker to work on my presentation...

Cheers,
    Steven

#########old message follows####################


I have just calculated histograms for two metrics suggested by John Conway,
the results of which I had intended to post on the appropriate pages of my
website(s). Unfortunately I am having major grief uploading to the site with
the B and C resolution results, so as an interim measure have provided the
figures to be inserted on the pages packaged in a zip file, available from
http://www.stevenheddle.co.uk/ALMA/JCMgifs.zip (it's almost exactly 1MB, so
it's hardly vast). It might take me a few days to get the webspace sorted
out, so I strongly advise you download it now if you want to see the results
before the PDR. It was zipped in Unix using zip, so WinZip also understands
it.

The zip file consists of a series of directories whose names should be self
explanatory by now (see any of my pages of results for the key) containing a
single file img9.gif, showing two histograms appropriate to the case defined
by the directory name-

1) The histogram on the left shows what has been discussed thus far as the
Conway metric- a series of rms values are calculated for pixels in the
difference image which in the corresponding smoothed model image fall into a
range of values. The ranges of values form a consecutive set of bins, with
the rightmost bin corresponding to pixels in the smoothed model whose values
fall between Imax (the max value in the smoothed image) and Imax/sqrt(10),
the bin to the left of this covering pixels whose value in the smoothed
image fall between Imax/sqrt(10) and Imax/10, continuing along in factors of
1/sqrt(10) til we get to Imax/1000. A final bin (with xvalue on the
histogram -3.5 to -3) mops up the pixels correponding to those in the
smoothed with a value below Imax/1000. The rms values calculated are scaled
by 1/Imax before plotting against the y axis so that the leftmost bins give
a value which may be interpreted as the reciprocal of off source dynamic
range. But in general, it's the scaled rms in the difference image as a
function of smoothed model intensity.

2) The histogram on the right shares the same x axis as that on the left,
but takes the rms values calculated and uses them to divide the arithmetic
mean of the intensity range of the bin in the smoothed model image (which
defined the pixels used in calculating the rms). So the y axis here is the
(binned) dynamic range as a function of smoothed model intensity.

Rereading this I see that I have defined dynamic range differently for each
graph- I'm sure John can do a more subtle interpretation of these measures
than me. In any case they seem to complement the existing fidelity measures
nicely by giving some indication of on and off source rms and dynamic range.


Cheers,
       Steven

Steven Heddle, Newington, Holm Road, Kirkwall, Orkney KW15 1PY
Tel: 01856 877119             Email: steven at heddle97.freeserve.co.uk
Fax: 0870 4039359           URL: http://www.heddle97.freeserve.co.uk