<font face="Verdana, Arial, Helvetica" size="2">Michael Bietenholz updated #11812<br />
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I don't get what UVCRS is doing - its finding some crossings but not others<br />
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<div style="margin-left: 40px;">Ticket ID: 11812</div>
<div style="margin-left: 40px;">URL: <a href="https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/11812">https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/11812</a></div>
<div style="margin-left: 40px;">Name: Michael Bietenholz</div>
<div style="margin-left: 40px;">Email address: <a href="mailto:mbieten@yorku.ca">mbieten@yorku.ca</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): -- Unassigned --</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: 21 March 2018 09:53 PM</div>
<div style="margin-left: 40px;">Updated: 21 March 2018 09:53 PM</div>
<div style="margin-left: 40px;">Reply due: 23 March 2018 09:54 PM (2d 0h 0m)</div>
<div style="margin-left: 40px;">Resolution due: 15 December 2020 12:00 AM (999d 2h 6m)</div>
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I don't get what UVCRS is doing - am I missing something obvious? I ran it on the little test data-set attached, and it<br />found one crossing (or rather near approach) between two baselines but not another, nearer one.<br />(31DEC18 AIPS, midnight job a couple of days ago)<br /><br />I ran UVCRS with APARM = 12 12 1 1 0; STOK 'RR' ; ANTENNAS 0<br /><br />so I'm expecting it to find baseline pairs that come within 12 Mlambda of each other in the uv-plane.<br /><br />It finds only one crossing<br /><br />UVCRS1: Ellipse with half axes 12.0 x 12.0 Megalamda<br />UVCRS1: Number of possible crossings = 4<br />UVCRS1: 1 1 2- 5 / 2- 8 1.869<br /><br />Here are the 4 possible vis in my tset data set - here's the UVPRT output:<br /><br /> Time Ant U(Kilo ) V(Kilo ) W(Kilo ) Amp Phas Wt<br />1 0/14:45:17.5 2- 5 12526.53 -29544.46 33484.21 4.456 -5 0.2402<br />2 0/14:45:17.5 2- 8 26670.29 -20700.05 26666.72 6.675 -4 0.1336<br />3 0/16:31:56.6 2- 5 22841.15 -31471.54 25272.92 3.571 -4 0.2055<br />4 0/16:31:56.8 2- 8 33388.70 -23948.15 12745.59 5.549 -4 0.1133<br /><br />Of those, the ones on lines 2,3 indeed have a difference in u-v positions of < 12 Mlambda, while the other pairs are > 12 Mlambda,<br /> and accordingly UVCRS prints out one crossing, . So far, its doing as I expect.<br /><br />However, that data also contains a rather closer pair of vis - only 5.6 Mlambda apart - why is UVCRS not picking these up?<br /><br /> Time Ant U(Kilo ) V(Kilo ) W(Kilo ) Amp Phas Wt<br />5 0/16:31:55.9 3- 6 87363.98 -12503.98 -85229.07 1.783 4 0.1078<br />6 0/16:31:58.7 5- 7 81823.39 -11645.47 -5923.63 4.349 -1 0.1034<br /><br />I thought maybe that the uv-ellipses for the first ones actually cross while those for 3-6 and 5-7 just approach, but as far as I can tell they latter ellipses *do* cross. Does the w-coordinate somehow matter?
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