[evlatests] X-Band Cals over Frequency

[Rick Perley]

One of the results of this Tcal excercise which encourages confidence is the run of calculated TCals values with frequency.

I took one of the 8-bit X-band flux density observations (31 January 2025) and generated the 'updated' Tcal values for all 16 spectral windows.  The results from two of the antennas (ea02 and ea08) are attached.  There are four plots, as the frequency coverage is in two 1 GHz-wide blocks, centered at 8.4 and 11.0 GHz.

The 'old' (lab measured) TCals are in open circles with dashed lines.  The 'new' (3C286-calibrated) TCals are in solid circles with solid lines.  RCP in black, RCP in red.  For all plots (but especially for ea02), the 'old' Tcals show considerable scatter over frequency, while the 'new' Tcals are quite smooth.  This is physically reasonable.
There are also offsets between the old and new values.

For all plots the eighth (highest frequency) 'new' TCal value is considerably offset from the other values.  This is an artifact, doubless caused by these two spectral windows are on the edge of the analog bandpass — the bandpass plots show a dramatic drop in amplitude (up to an order of magnitude) in this spectral window.

Rick
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listmgr.nrao.edu/pipermail/evlatests/attachments/20260828/45ee3186/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ea08TCals-X-Hi.png
Type: image/png
Size: 12639 bytes
Desc: ea08TCals-X-Hi.png
URL: <http://listmgr.nrao.edu/pipermail/evlatests/attachments/20260828/45ee3186/attachment-0004.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ea08TCals-X-Lo.png
Type: image/png
Size: 12163 bytes
Desc: ea08TCals-X-Lo.png
URL: <http://listmgr.nrao.edu/pipermail/evlatests/attachments/20260828/45ee3186/attachment-0005.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ea02TCals-X-Hi.png
Type: image/png
Size: 12406 bytes
Desc: ea02TCals-X-Hi.png
URL: <http://listmgr.nrao.edu/pipermail/evlatests/attachments/20260828/45ee3186/attachment-0006.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ea02TCals-X-Lo.png
Type: image/png
Size: 12769 bytes
Desc: ea02TCals-X-Lo.png
URL: <http://listmgr.nrao.edu/pipermail/evlatests/attachments/20260828/45ee3186/attachment-0007.png>