Q-band

In order to see if Q-band observations could be made part of the Standard Field tests, I did a short observation of 0212+735 at Q-band in the 1995 A configuration run. This confirmed earlier measurements of that source, showing it to be a suitable Q-band calibrator (Chandler 1995). So, I observed the Standard Field at Q-band in the 1995 B configuration run. Mars was used to set the absolute scale, with an observation of 3C286 as confirmation of the scale. Images made of the data showed that there were indeed no measurable sources in the field at Q-band. So, again, the performance could be measured by the fluctuations in the visibilities. The value of $\Delta\, S$, averaged over all IF's, Stokes, and Real and Imaginary, was $\sim 203$ mJy. This implied a value of $T_{\rm sys}/ \eta_a$ of $\sim 865$ K, and a value of $\sim 103$ for Rick's $K$ parameter. Note that this was at an elevation of $\sim 30^\circ$, however, so these values cannot be compared easily with numbers at zenith. The values of the noise in the images is shown in Table 6, where the images were made with both IF's averaged. There were about 19000 visibilities in each ``IF'', so the predicted noise in the images from the value of $\Delta\, S$ was $\sim 0.740$ mJy/bm, very close to the observed values.

Table: Q-band noise measurement (map based)

Stokes	$S_{\rm rms}$
	(mJy/bm)
I	0.761
Q	0.757
U	0.730
V	0.775

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References

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=1cm=1 Bagri, D. S., Noise Performance of the Upgraded L-Band System, VLA Test Memorandum No. 167, 1993

=1cm=1 Bagri, D. S., and P. Lilie, System Temperature and Noise Cal Measurements Using Moon, VLA Test Memorandum No. 170, 1993

=1cm=1 Chandler, C., VLA Calibrators at Q-band, VLA Test Memorandum No. 192, 1995

=1cm=1 Crane, P. C., Observations of the Ubiquitous 1400 MHz Birdie, VLA Test Memorandum No. 133, 1982

=1cm=1 Crane, P. C., and P. J. Napier, Sensitivity, in Synthesis Imaging in Radio Astronomy, (R. A. Perley, F. A. Schwab, and A. H. Bridle, Eds.), pp. 139-165, Astronomical Society of the Pacific Conference Series, San Francisco, CA., 1994

=1cm=1 Janes, C., Strong Interference at the VLA, 1994, VLA-VLBA Interference Memorandum No. 5, 1995

=1cm=1 Lilie, P., VLA L-Band $\rm T_{sys}$ vs. Elevation, report dated May 16, 1994

=1cm=1 Lilie, P., Moon and $\rm T_{cal}, T_{sys}$, VLA Test Memorandum No. 165, 1992

=1cm=1 Perley, R. A., J. van Gorkom, and A. Rots, Radio Interference in the 20-cm Band, VLA Test Memorandum No. 139, 1983

=1cm=1 Thompson, A. R., J. M. Moran, and G. W. Swenson, Jr., Interferometry and Synthesis Imaging in Radio Astronomy