<font face="Verdana, Arial, Helvetica" size="2">Michael Bietenholz updated #11758<br />
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CALIB puts different SNR into output SN table depending in APARM(6)<br />
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<div style="margin-left: 40px;">Ticket ID: 11758</div>
<div style="margin-left: 40px;">URL: <a href="https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/11758">https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/11758</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: 09 March 2018 10:28 AM</div>
<div style="margin-left: 40px;">Updated: 09 March 2018 10:28 AM</div>
<div style="margin-left: 40px;">Reply due: 13 March 2018 10:28 AM (4d 0h 0m)</div>
<div style="margin-left: 40px;">Resolution due: 03 December 2020 12:00 AM (999d 13h 32m)</div>
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[31DEC18 AIPS updated yesterday on Ubuntu 16.04; VLBA data]<br /><br />CALIB produces a different SN table depending on whether APARM(6)=0 or =3. I would have thought it should just produce an identical SN table with APARM(6)=3 but print more messages, but the SNR in the output SN tables is different. In my case, the amp and phase gain solutions seemed to be identical, so it probably doesn't affect the output data, but it makes results harder to interpret.<br /><br />Here's a LISTR,OPTY=GAIN printout of an SN table made with APARM(6)=0. Note the presence of a number of values with SNR[scaled]=500 (ie. exactly 5.00) which seem unlikely given the other values are >10000 (sorry - column alignment seems to get munged when pasting into the ticket window). I'm guessing (see below) that the SNR=5.00 is some kind of flag indicating closure errors.<br /><br />Solution SNR, 1000 = 10.0<br />Stokes = R IF = 1 Freq = 15.143875000 GHz<br /> <br /> Time Source -----01-----02-----04-----05-----07-----08-----09<br /> <br />Day # 0<br />13:27:23.0 SGRA 117693 500 500 47687 142446<br />14:29:07.0 SGRA 334927 500 500 121146 287779<br />15:29:08.5 SGRA 22712 500 124377 500 500 92694<br />16:29:10.0 SGRA 500 500 90437 500 500 589853<br />17:29:12.0 SGRA 500 37507 273674 500 500 500 73031<br /><br />Here's CALIB run exactly the same way, but with APARM(6)=3 (same LISTR scaling factor)<br /><br />13:27:23.0 SGRA 59529 26567 117378 47154 142446<br />14:29:07.0 SGRA 119715 57391 140007 117627 287779<br />15:29:08.5 SGRA 30344 127393 89305 121082 35837 105587<br />16:29:10.0 SGRA 22930 36051 23348 51927 85758 212770<br />17:29:12.0 SGRA 19386 40394 41224 50993 3123 73856 40852<br /><br /><br />Looking at CALIB.FOR, I note that in the case APARM(6)=0; DOFLAG=0, you get XDOFL=2,5, whereas if APARM(6)=3 you wind up with XDOFL=99, so I think its somehow treating closure errors different depending on whether APARM(6)=3 or 0. <br /><br />I can of course send you the data set that produced the above results, but I think it probably is not due to a peculiarity of my data other than perhaps that there are significant closure errors in it.
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