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<p>Hi Rick,</p>
<p><br>
</p>
<p>I know it's laborious, but would you be able to check antenna
ea01 in Ku Band at 15.0 or 17.0 GHz in LCP instead of 13.9 GHz?</p>
<p><br>
</p>
<p>Ku S/N 016 on ea01 is an interesting case because the
lab-measured and derived curves are quite different (see the first
page of the PDF I circulated in a separate thread), and it's been
on a long time since Dec 2016. It just so happens that at 13.9 GHz
the two curves cross and the numbers are almost the same around
~1.6 K. But at 12, 15, and 17 GHz they are close to a factor of
two different. I'm very curious if you see the same overall
values:</p>
<p><br>
</p>
<p>ea01 LCP (Ku Rcvr# 16)</p>
<p>12 GHz: 0.8 K<br>
15 GHz: 2.8 K<br>
17 GHz: 0.5 K</p>
<p><br>
</p>
<p>If not, then that means that something must be going wrong with
the tipping scan method systematically for this receiver and
antenna for some reason. Otherwise there's good agreement just
eyeballing the values in your table against the charts.</p>
<p><br>
</p>
<p>Clear skies,<br>
Brian</p>
<br>
<div class="moz-cite-prefix">On 9/3/26 1:57 PM, Rick Perley via
evlatests wrote:<br>
</div>
<blockquote type="cite" cite="mid:DM4PR14MB7132F228FA981C46FF908E82D7B62@DM4PR14MB7132.namprd14.prod.outlook.com">
<style type="text/css" style="display:none;">P {margin-top:0;margin-bottom:0;}</style>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
The procedure to generate 'sky-calibrated' Tcals for our noise
diodes allows investigation of long-term stability. </div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
The results for Ku-band are especially illuminating. </div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
As described earlier, we use the known flux density of 3C286 to
generate corrected values for the noise diode temperature. </div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
For Ku-band, there are 14 antennas whose receivers have not
changed since 2019. I show below the derived values of Tcal at
13.936 GHz. </div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Ant Rcvr# 2019Jan31 2019Oct24 2021Sep09 2023Oct03
2025Jan31 2025Mar09</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
RCP LCP RCP LCP RCP
LCP RCP LCP RCP LCP RCP LCP</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
--------------------------------------------------------------------------------------------------------------------------------------------------------</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
01 16 1.56 1.85 1.65 1.86 1.52 1.74
1.53 1.73 - - 1.51 1.80</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
03 13 0.70 0.78 0.69 0.81 0.68 0.75
0.69 0.80 0.67 0.79 0.69 0.79</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
04 17 1.93 1.88 1.99 1.94 1.89 1.84
2.00 1.87 2.00 1.88 2.00 1.85</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
05 14 2.23 2.35 2.32 2.41 —- ---
2.37 2.48 2.42 2.44 -- --</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
07 05 1.79 1.82 1.78 1.78 1.86 1.81
-- -- 1.41 1.25 1.86 1.82</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
09 19 1.79 1.77 — -- 1.69 1.73
1.70 1.76 1.81 1.82 1.71 1.74</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
11 27 1.30 1.26 1.30 1.30 1.31 1.45
1.33 1.41 1.34 1.39 1.34 1.44</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
15 28 1.24 1.30 1.27 1.36 1.40 1.46
1.45 1.57 1.38 1.47 1.33 1.41</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
18 12 1.89 1.87 1.99 2.00 2.25 2.29
2.34 2.39 2.32 2.34 2.28 2.31</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
19 02 1.90 1.90 3.58 3.18 1.50 1.42
1.58 1.50 1.52 1.47 1.56 1.47 Values in 2019
questionable</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
22 07 3.00 2.99 2.91 3.04 3.06 2.82
3.20 2.97 3.19 2.98 2.99 2.89</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
23 24 1.70 1.71 1.68 1.74 1.70 1.68
1.74 1.67 1.75 1.67 1.73 1.66</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
26 25 1.24 1.15 1.19 1.20 1.17 1.17
1.20 1.16 1.25 1.16 1.19 1.18</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
28 06 —- --- 1.47 1.35 1.51 1.43
1.55 1.43 1.51 1.44 1.51 1.45</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
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<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Except for ea19 (whose very different values in 2019 have no
ready explanation), the rms stability over time, for a given
antenna/receiver/polarization is between 2 and 4%. Curiously,
for the four antennas with the same receivers prior to 2019
(dating back to 2014) show Tcals about 10% lower than the
numbers shown above. Other bands, particularly L-band, show
considerable variations in their derived Tcals for dates before
2019. After this date, all bands that I've investigated so far
(L through Ku) show similarly to the numbers above, for nearly
all antennas. </div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
The few percent variation from year to year for a given antenna
is easily accounted for by temperature variations of the
switched diode, pointing variations, and sky opacity differing
from the simple model used in the gain calibration. </div>
<div class="elementToProof" style="font-family: Aptos, "Aptos_EmbeddedFont", "Aptos_MSFontService", Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
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<br>
</div>
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<fieldset class="moz-mime-attachment-header"></fieldset>
<pre wrap="" class="moz-quote-pre">_______________________________________________
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</pre>
</blockquote>
<pre class="moz-signature" cols="72">--
Brian E. Svoboda, PhD
Associate Scientist
National Radio Astronomy Observatory (NRAO)
Office: DSOC 312
Office Phone: +1 (575) 835-7246</pre>
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