<font face="Verdana, Arial, Helvetica" size="2">Eric Greisen updated #17215<br />
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Regarding OBIT and AIPS: BDFLIST and BDF2AIPS<br />
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<div style="margin-left: 40px;">Ticket ID: 17215</div>
<div style="margin-left: 40px;">URL: <a href="https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/17215">https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/17215</a></div>
<div style="margin-left: 40px;">Name: Juhi Tiwari</div>
<div style="margin-left: 40px;">Email address: <a href="mailto:j_aquarian_t@yahoo.co.in">j_aquarian_t@yahoo.co.in</a></div>
<div style="margin-left: 40px;">Creator: User</div>
<div style="margin-left: 40px;">Department: AIPS Data Reduction</div>
<div style="margin-left: 40px;">Staff (Owner): Eric Greisen</div>
<div style="margin-left: 40px;">Type: Issue</div>
<div style="margin-left: 40px;">Status: Open</div>
<div style="margin-left: 40px;">Priority: Default</div>
<div style="margin-left: 40px;">SLA: NRAO E2E</div>
<div style="margin-left: 40px;">Template group: Default</div>
<div style="margin-left: 40px;">Created: 26 October 2020 08:42 AM</div>
<div style="margin-left: 40px;">Updated: 24 November 2020 09:52 AM</div>
<div style="margin-left: 40px;">Reply due: 26 November 2020 08:54 AM (1d 23h 2m)</div>
<div style="margin-left: 40px;">Resolution due: 12 August 2023 05:00 PM (991d 7h 8m)</div>
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<p>1. You have not understood a fundamental fact of aperture synthesis. A point source (your calibrators) should have the same fringe amplitude on all baselines after calibration. However a complex field such as the one you are imaging will have fringe amplitudes that vary widely since the Fourier transform of a complicated field is complex (in both senses of the word).</p>
<p>2. You have figured out quite a few AIPS adverbs to make such pretty images. PIXRANGE may be used to limit the range of values displayed. The negative side of the current pixel range is presumably due to errors or incomplete Cleaning. Adding more data will change that. The peak brightness is a function of spatial resolution and will change of the new data are at longer or shorter baselines.</p>
<p>3. To make images with the appropriate sub-image peak values you may use the task SUBIM to actually make the sub-images in your catalog. Then the pixel ranges will be correct for the sub-image. You do not want to make just a sub-image with IMAGR since both sources are in the visibility data and so both must be imaged and Cleaned together. I suppose you could make 2 facets one on each sub-image but SUBIM is quick and easy.</p>
<p>4. AIPS task FITTP will write out a FITS file suitable for DS9. AIPS can also read the optical and other FITS filevpn.aoc.nrao.edu/anyconnects. Note that the pixel size, image size, and even orientation of these images will be different from your radio image. Task OHGEO can be used to regrid one of them to match the coordinate structure of the other. Then KNTR can do grey-scale of one with contours of the other. There are also ways to make 3-color images from images in different bands. See TVRGB and LAYER.</p>
<p>5. I often use the task SETFC to recommend image and cell sizes. At the larger configurations one will need to make multi-facet images when at L band.</p>
<p>6. The TV being used by someone else is a real message. It means that some process was using the TV and either is still using it or had an abnormal termination. The TV has a lock server that controls access. It can tell you when this condition arises quickly. Without it, an attempt to open the TV when it is busy would produce a look wait with no messages to say what is happening. Your solution is drastic but will work. Pay attention to what is going on just before and when you get this message and you should be able to diagnose the problem.</p>
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<p>Eric Greisen</p>
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