<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<div class="moz-cite-prefix">On 7/29/2020 2:48 PM, Alexey Nikonov
via Daip wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAFoAC90+OGu-MWtt1NkYLksYgoLP+Ar7efXasVZBR14XuFLNjw@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<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" class="gmail_signature"
data-smartmail="gmail_signature">
<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>
<fieldset class="mimeAttachmentHeader"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
Daip mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Daip@listmgr.nrao.edu">Daip@listmgr.nrao.edu</a>
<a class="moz-txt-link-freetext" href="https://listmgr.nrao.edu/mailman/listinfo/daip">https://listmgr.nrao.edu/mailman/listinfo/daip</a>
</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>
<p><br>
</p>
<div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2">
<br /><br />
<hr style='border:none; color:#909090; background-color:#B0B0B0; height: 1px; width: 99%;' />
<table style='border-collapse:collapse;border:none;'>
<tr>
<td style='border:none;padding:0px 15px 0px 8px'>
<a href="https://www.avast.com/antivirus">
<img border=0 src="https://static.avast.com/emails/avast-mail-stamp.png" alt="Avast logo" />
</a>
</td>
<td>
<p style='color:#3d4d5a; font-family:"Calibri","Verdana","Arial","Helvetica"; font-size:12pt;'>
This email has been checked for viruses by Avast antivirus software.
<br><a href="https://www.avast.com/antivirus">www.avast.com</a>
</p>
</td>
</tr>
</table>
<br />
<a href="#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2" width="1" height="1"> </a></div></body>
</html>