<div dir="ltr"><div><div><div>OK, so let me make sure I understand:<br></div><ul><li>In SDGRD I do not need to add a fake RA and Dec (I can leave APARM blank), and therefor after SDGRD I do not need to change the header to change the reference coordinate to Glong and Glat because SDGRD will be able to handle the coordinate information. </li>
<li>Blanking the cube will help me get better moment maps (I usually use a channel range; will that be enough?)</li><li>In XMOM I should use OPTYPE 'MAX' with ICUT=0 and FLUX=-1000000. </li></ul></div></div>Thank you so much for your help!-Trisha<br>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Dec 24, 2013 at 5:33 PM, Eric Greisen <span dir="ltr"><<a href="mailto:egreisen@nrao.edu" target="_blank">egreisen@nrao.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Many thanks for the FITS file - it will help me test things.<br>
<br>
I ran SDGRD on your data and am shocked at how smart it is. It sets the reference declination to 0 at a correct (way offset) pixel location and makes a proper image whether or not one specifies APARM.<br>
<br>
But XMOM cannot be run blindly - I tried it after TRANS and found that no spatial pixel has a legitimate moment if one allows all image values. All of them find that the predominant velocity channel is either < 1 or > N (probably all the < 1). Moment analysis assumes a real and positive signal - with a lot of channels at values < 0, it fails. In fact, the times I have done moment analysis I have blanked the cube very carefully so that channels that are clearly noise are omitted. The OPTYPE 'MAX' avoids some of these issues and makes useful images for you.<br>
<br>
With your imaging parameters 1543 of the 1600 image pixels have values - the corners are missing a bit.<br>
<br>
thanks<span class="HOEnZb"><font color="#888888"><br>
<br>
Eric Greisen<br>
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