[alma-config] Re. Mark's comments on the Fidelity images

[Steven]

Thanks for the comments Mark.

Regarding the technical points raised regarding the creation of the results:

1) Negative fidelities- these do indeed arise from negative values in the
model brightness distribution (or in this case the brightness distribution
of the model dowsampled to the appropriate pixel scale and convolved with
the specified CLEAN beam). Doesthe consensus say redo the results using the
absolute value of the smoothed model for the division, or use the absolute
value of the model from the word go i.e. redo the imaging and CLEANing as
well, prior to differencing etc.

2) I believe the quoted mean fidelities are correct, with the log scale of
the histogram perhaps being deceptive.
Considering the  CCMAR_4-23B7 case (spiral, 4 hour track, imaging Mars, -23
d) with a quoted mean of 11,  the attached text file shows the full output
from running IMEAN on the fidelity image, with the same task used to
generate the histogram. The histogram is indeed approximately flat out to a
fidelity of 50, with the important exception of the first bar of fidelities
between plus and minus 0.19 which contains 44,000 of the 66,000 pixels,
implying a ball park mean of approximately (25*22/66)=8.3, with the actual
figure plausibly raised to 11 by the slight peak in the histogram between 37
and 45.

Keep the comments coming folks. In particular, what are your feelings about
having different truncation values for the denominators of corresponding K
and C (ring and spiral) cases when calculating the fidelity image? Also do
you wish the fidelity range to be calculated?

Do we have a telephone meeting coming up?

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
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