Cband calibration.

23sep 2000 (last mod 16feb01..focus gain)

Description:

On/off position switching on continuum sources was done at cband using the correlator. The setup was:

One minute integration's on and then off source followed by a 10 second cal on/off in the off source position.

Try to track sources rise to set.

Record 4 25 Mhz bands centered at RF frequencies: 5000, 4900, 5100, and 5200 Mhz.

Use the total power information, cal values, and source flux to compute tsys, gain, sefd.

Fit the data to a function of (az,za).

Compare the measured gain with the expected gain. Include losses from pitch, roll, and focus.

Daily Info:

The dates for the observations and the sources observed are:

25aug00 : J0318+164 (CTA21)

26aug00 : J0318+164 (CTA21)

27aug00 : B0116+082

29aug00 : B1609+266

01sep00 : B0453+227

03sep00 : J2445+099

The high uncorrelated cal was used during the runs (this is 2 separate diodes).

Cal values by freq and polarization
Freq [Mhz]	cal polA [K]	cal polB [K]
5000	26.9	25.6
4900	26.8	26.4
5100	27.4	25.6
5200	27.0	24.5

Plots of combined data: sefd,tsys,avgain, calscale, and fractional polarization

The plots have all the data over plotted with different symbols for each source. Dotted lines are polA and dashed lines are polB. All four frequencies are over plotted (so there are 8 symbols arranged vertically at each za). The figures are:

SEFD vs za.
Tsys vs za. The separate lines are different polarization and frequencies.
Gain (average) vs za. The average is (gainA+gainB)*.5. This was used since the cband receiver uses linear polarization and one of the source was polarized.
Cal scale factor vs za. This is (cal In Kelvins)/(Cal deflection in correlator units). This should be a flat line for each run since the attenuators were not changed (within a source). Variations are probably do to gain changes in the if/lo.
Fractional polarization defined as (gaina-gainb)/(gaina+gainb). All 4 frequencies are over plotted. The literature for B0453+227 (open box source) quotes a fractional polarization of 8.1% at cband. This is very close to what we measure.

Plots of f(az,za): g(az,za), tsys(az,za), g/t(az,za), and fracPol(az,za)

The average gain, Tsys, Gain/Tsys, and fractional polarization (at 5 Ghz) are plotted in a 2-d plot vs az,za. Up is feed in the north and to the left is the feed in the west (when the source is rising). The length of the arrow is an absolute measure of the value. The angle the arrow makes with the vertical is a relative measure of the strength. The table at the lower left averages the value over all the dish, za 0-5,5-10,10-15, and 15-20 degrees. The figures are:

Average gain [K/Jy]. 1 tick= 1 K/Jy. Horizontal is maximum and 180 deg (down) is 1/2 of maximum.
Tsys [Kelvins]. 1 tick=10K. Up is minimum temperature and 180 deg (down) is 2*TsysMin.
Gain/Tsys [Tsys/Jy]. 1 tick= .03 Tsys/Jy. up is maximum, down is 1/2 maximum.
Fractional polarization. 1 tick=.02 (2%). Up is 0 fracPol, down is 10%.

Fitting the data to f(az,za):

The data is fit to:

f(az,za)=c0 + c1*(za-10)+c2*(za-10)^2+c3*(za-10)^3+

c4*cos( az)+c5*sin( az)+c6*cos(2az)+c7*sin(2az)+

c8*cos(3az)+c9*sin(3az)

Sefd-fit, Tsys-fit, gainAvg-fit These plots have all 4 frequencies and polA,B over plotted. The (za-10) terms are for za 0 through 20 degrees (unlike some of the other fits that used (za-14) for za > 14).

SEFD - fit. Units are Jy/Tsys.
Tsys - fit. Units are deg K.
AvgGain - Fit in K/Jy.

gainBySample,gainOverplotFit,PRFloss, and prfAzTerms. These plots take a closer look at the gain fit and how the azimuth terms of the fit compare to the azimuth terms of the gain loss computed from pitch,roll, and focus. The figures are:

AvgGain versus sample for all 4 frequencies.
AvgGain versus sample for 5000 Ghz with the fit over plotted. The polarized source B0453+227 is not fitting very well even though we're using the average gain.
GainLoss computed from pitch,roll, and focus. The gain is down by 55% at high za.
Fit to avgGain 5000 Mhz. The upper coefficients are the fit to the measured data. The bottom coefficients are the gain computed from the pitch, roll, and focus errors, and then scaled to a maximum gain of 3.2 Jy (this was the measured maximum). The plots show the azimuth terms for each fit (solid measured data, dots - pitch,roll,focus). The 3 az terms line up in phase pretty well. The 1az and 2az terms are out of phase. They are probably caused by residuals from the za fit looking like azimuth term. We have undersampled in the (az,za) plane especially at low zenith angle where we only have samples close to 90 and 270 degrees.

az components of SEFD,Tsys,Gain, and avgGain . These plots show the azimuth components (1az,2az,3az) for the sefd, tsys, gain, and average gain. All 4 frequencies are over plotted. PolA is solid and polB is the dotted line. The coefficients for 5000 Mhz are also printed on the plot. PolA on the top and polB on the lower portion.

Warnings on using the fits:

There are only 5 sources used in the fits. Of these 3 are in the south and 2 are in the north. There are no rise to set tracks for any of the northern sources and there are no sources above 27 deg dec or below 8 deg dec. For sources with decs close to those used in the fit, the sigmas of the fits should be ok. For high or low dec sources, care should be taken.

Coefficients from the fits:

Below are listed the coefficients from the various fits. The first column in each row specifies the data that was fit.
For gainAvg there is just one fit while gain,tsys,sefd have a separate fit for polA and polB.
> Aug/sep00 sbn
> last computed: Sat Sep 23 14:59:40 2000
> fit Ids
> 1 GainAvg
> 2 Gain
> 3 tsys
> 4 sefd

fId

frq

c0

za-10

(za-10)^2

(za-10)^3

cosAz

sinAz

cos2Az

sin2az

cos3az

sin3az

sigma

pol

calVal

5000.

1.7538e+00

-1.0252e-01

2.2021e-03

1.0623e-04

4.5354e-02

1.2862e-01

-2.3625e-01

-7.3604e-02

-1.2753e-01

-1.0821e-01

1.6848e-01

0.00

4900.

1.8711e+00

-1.0681e-01

2.1033e-03

7.7822e-05

6.3580e-02

1.3139e-01

-2.4989e-01

-7.6052e-02

-1.2665e-01

-1.1205e-01

1.7032e-01

0.00

5100.

1.6987e+00

-9.8949e-02

2.4332e-03

6.6633e-05

1.4377e-02

1.2597e-01

-2.3501e-01

-7.5637e-02

-1.1814e-01

-1.0295e-01

1.6653e-01

0.00

5200.

1.5757e+00

-9.9210e-02

2.4778e-03

7.8476e-05

2.7343e-02

1.1970e-01

-2.3414e-01

-6.5800e-02

-1.1183e-01

-1.0053e-01

1.5696e-01

0.00

5000.

1.7595e+00

-1.0173e-01

1.6072e-03

1.4080e-04

3.8623e-02

1.7846e-01

-2.5155e-01

-1.2617e-01

-8.9766e-02

-9.6326e-02

1.5601e-01

26.9

5000.

1.7482e+00

-1.0332e-01

2.7971e-03

7.1665e-05

5.2085e-02

7.8781e-02

-2.2096e-01

-2.1039e-02

-1.6529e-01

-1.2010e-01

1.8550e-01

25.6

4900.

1.8710e+00

-1.0566e-01

1.5471e-03

1.1014e-04

6.2089e-02

1.7709e-01

-2.7138e-01

-1.2596e-01

-8.5959e-02

-1.0270e-01

1.5535e-01

26.8

4900.

1.8711e+00

-1.0796e-01

2.6596e-03

4.5504e-05

6.5072e-02

8.5684e-02

-2.2841e-01

-2.6142e-02

-1.6735e-01

-1.2139e-01

1.9027e-01

26.4

5100.

1.7204e+00

-9.7922e-02

1.8217e-03

9.6961e-05

1.5222e-02

1.7909e-01

-2.5218e-01

-1.2492e-01

-8.1434e-02

-9.2455e-02

1.5428e-01

27.4

5100.

1.6770e+00

-9.9977e-02

3.0448e-03

3.6305e-05

1.3532e-02

7.2843e-02

-2.1784e-01

-2.6354e-02

-1.5484e-01

-1.1344e-01

1.8320e-01

25.6

5200.

1.5751e+00

-9.8451e-02

1.9623e-03

1.2240e-04

3.1590e-02

1.5949e-01

-2.4937e-01

-1.0773e-01

-7.7952e-02

-9.1447e-02

1.4373e-01

27.0

5200.

1.5763e+00

-9.9969e-02

2.9932e-03

3.4555e-05

2.3096e-02

7.9912e-02

-2.1891e-01

-2.3868e-02

-1.4570e-01

-1.0962e-01

1.7479e-01

24.5

5000.

2.9646e+01

-5.2949e-03

2.6610e-02

4.7184e-03

2.4074e-01

-1.0340e-01

-1.4674e-01

8.0792e-02

5.8742e-02

-7.4206e-02

3.6441e-01

26.9

5000.

3.3267e+01

5.2876e-03

2.5501e-02

4.2942e-03

3.2478e-01

-1.1396e-01

2.2163e-01

2.4978e-01

-2.4552e-02

-1.3815e-01

3.5408e-01

25.6

4900.

2.9410e+01

-1.0514e-02

2.8579e-02

5.0288e-03

3.3184e-01

-5.6961e-02

-1.5974e-01

3.1137e-02

5.1334e-02

-4.0229e-02

3.6840e-01

26.8

4900.

3.2641e+01

4.5705e-03

2.6681e-02

4.5254e-03

3.4549e-01

-7.9204e-02

2.3530e-01

1.7151e-01

-1.9551e-04

-6.4149e-02

3.2038e-01

26.4

5100.

3.1710e+01

-1.0501e-02

2.5680e-02

4.6052e-03

3.1931e-01

-6.1445e-02

-2.3277e-01

3.1076e-02

7.1353e-02

-5.6437e-02

3.5082e-01

27.4

5100.

3.5399e+01

-2.0882e-03

2.6172e-02

4.1104e-03

2.1904e-01

-9.8081e-02

1.8428e-01

2.1979e-01

4.8789e-02

-8.4922e-02

3.0030e-01

25.6

5200.

3.2746e+01

-1.8575e-02

2.7299e-02

4.6411e-03

1.9768e-01

-8.9377e-02

-2.7594e-01

2.1869e-02

1.2002e-01

-2.3809e-02

3.3813e-01

27.0

5200.

3.8200e+01

-5.1859e-03

2.9278e-02

4.4261e-03

1.1369e-01

-1.1408e-01

2.5612e-01

2.2965e-01

1.1856e-01

-4.6731e-02

3.4049e-01

24.5

5000.

1.7241e+01

7.0702e-01

3.4483e-02

5.5505e-03

-3.3028e-01

-2.7133e+00

1.7465e+00

1.6785e+00

1.2727e+00

8.4311e-01

2.0695e+00

0.00

5000.

1.9495e+01

7.8065e-01

2.3975e-02

5.5690e-03

-4.6761e-01

-1.7991e+00

1.7915e+00

7.2553e-01

2.1500e+00

8.4309e-01

2.2767e+00

0.00

4900.

1.5991e+01

6.1422e-01

3.4339e-02

6.2111e-03

-3.1686e-01

-2.2721e+00

1.6682e+00

1.3720e+00

1.0068e+00

8.3401e-01

1.6178e+00

0.00

4900.

1.7812e+01

6.9026e-01

2.7024e-02

5.9715e-03

-4.5340e-01

-1.6187e+00

1.6013e+00

6.6129e-01

1.8809e+00

7.4953e-01

1.9713e+00

0.00

5100.

1.8834e+01

7.2955e-01

3.1566e-02

6.7915e-03

-1.7929e-02

-2.8269e+00

2.0495e+00

1.6149e+00

1.1538e+00

1.0240e+00

2.0251e+00

0.00

5100.

2.1639e+01

8.4592e-01

2.1025e-02

6.7685e-03

-1.0466e-01

-1.9057e+00

2.1549e+00

7.5133e-01

2.2469e+00

9.8772e-01

2.4585e+00

0.00

5200.

2.1252e+01

8.8631e-01

3.6725e-02

7.3856e-03

-2.6240e-01

-3.2168e+00

2.3352e+00

1.8293e+00

1.4162e+00

1.2037e+00

2.3313e+00

0.00

5200.

2.4848e+01

9.9814e-01

2.9116e-02

8.7642e-03

-2.7345e-01

-2.4805e+00

2.5540e+00

9.6929e-01

2.6657e+00

1.1516e+00

2.9753e+00

0.00

processing: x101/cb/calsep00/doit.pro

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