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Very interesting, Rick - thanks for sharing. Are the four remaining 'old' ACU antennas scheduled for an update?</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> evlatests <evlatests-bounces@listmgr.nrao.edu> on behalf of Rick Perley via evlatests <evlatests@listmgr.nrao.edu><br>
<b>Sent:</b> Thursday, May 29, 2025 6:27 PM<br>
<b>To:</b> evlatests <evlatests@nrao.edu><br>
<b>Subject:</b> [evlatests] ACUs -- Old vs New</font>
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<div>I continue to troll through the 'flux density' data, taken earlier this year. </div>
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<div class="x_elementToProof">The observations include many long slews between the sources, so I can judge how long it takes the antennas to move from one source to another, when the separation is large. </div>
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It is quickly seen there is a major difference between antennas: ea04, 15, 18 and 20 are
<b>always </b>on source before the others. The difference can be large — up to 30 seconds (!!!) for really big azimuth changes (meaning, about 8.5 minutes for the fast antennas, vs 9 minutes for the slower ones, for a full turn in azimuth.)</div>
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What's special about those four antennas? — They are all 'old' ACU antennas, and indeed are the only remaining 'old' ACU antennas. (ea05 is 'old', but was out of the array). </div>
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Question: Is this difference expected? </div>
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The good news: For the 'new' antennas, the arrival times on source — even for the very longest slews — are identical — within 1 second even for slews longer than 8 minutes. </div>
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Rick</div>
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