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<div class="moz-cite-prefix">On 8/2/2020 3:20 AM, Alexey Nikonov
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAFoAC92odq6v3xKYL9My7B8cBEad4TWi+W2Eia+ZFMaPKNJMpw@mail.gmail.com">
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<div dir="ltr">Thank you for your answer, Eric!
<div><br>
</div>
<div>I`ve tried VTESS with different odd inputs, but didn't get
the result. Did you have experience on MEM mapping? Maybe
other software exists to make MEM a little easier?</div>
</div>
</blockquote>
<p><br>
</p>
<p>You might try giving VTESS the DIFMAP Clean image as the initial
guess in IN3NAME. I have little experience with MEM. Multi-scale
Clean in IMAGR sometimes helps with extended sources.</p>
<p>Eric Greisen<br>
</p>
<blockquote type="cite"
cite="mid:CAFoAC92odq6v3xKYL9My7B8cBEad4TWi+W2Eia+ZFMaPKNJMpw@mail.gmail.com"><br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">чт, 30 июл. 2020 г. в 01:05,
Eric Greisen <<a href="mailto:egreisen@nrao.edu"
moz-do-not-send="true">egreisen@nrao.edu</a>>:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<div>On 7/29/2020 2:48 PM, Alexey Nikonov via Daip wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">Hello,
<div><br>
</div>
<div>I`m writing to ask help in mem VTESS mapping. Can
I?</div>
<div><br>
</div>
<div>I`ve self-calibrated and restored image of an
extended source 1308+326 with CLEAN in DIFMAP. So I
know the estimate of noise level from this map.</div>
<div><br>
</div>
<div>Loaded to AIPS calibrated UV-file just to do VTESS
mem deconvolution. Done IMAGR with 0 iterations to
obtain beam and dirty map.<br clear="all">
<div>As I know in CLEAN image results I`ve pick the
same cellsize as in DIFMAP and twice image size
compared to source area, that can be seen in CLEAN
image. </div>
<div><br>
</div>
<div>After that VTESS couldn`t find a solution.
Instead of extended structure I can see only one
Gaussian peak and noise. </div>
<div><br>
</div>
<div>I couldn`t find many recommendation to VTESS.
Documentation says that noise is crucial parameter,
so I played with it, but nothing changed. Also
played with FLUX parameter and number of
iterations. </div>
<div><br>
</div>
<div>Can you please help :)</div>
<div><br>
</div>
-- <br>
<div dir="ltr">
<div dir="ltr">
<div>Sincerely yours,</div>
<div>Aleksei Nikonov</div>
<div>AstroSpace Center,</div>
<div>Lebedev Physical Institute,</div>
<div>Moscow, Russia</div>
</div>
</div>
</div>
</div>
<br>
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</pre>
</blockquote>
<p><br>
</p>
<p>VTESS is a peculiar task whose author was never even in
the AIPS group. It can do nice things but with strange
inputs at times. The Y2K test we run on a Cygnus A data
set sets NOISE=.0024 with is close to the noise in the
result. But FLUX is set to -18 (note minus sign!) when
the actual flux will turn out to be ~200 Jy. In other
words odd inputs are needed to kick the task into
converging on a good answer. (It did not work when I set
FLUX=200 despite the excellent quality of the data.)</p>
<p>Good luck</p>
<p>Eric Greisen</p>
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