---

Sections:

---

History:

• 01nov10-17nov10
• : gortex cover comes loose, moisture gets into mouth of horn.
  
• Tsys goes up. repaired and back to normal on 17nov10.
• 28aug06: new cband cal values installed (measured back in jul06).
• 06jul06: remeausured the cal values. Needed from the 25may06 tightening of pola.
• 25may06: Found that sma connector for polA cal was loose. Cal had jumped back on 02feb06. After tightening, the Tsys did not jump back to the pre 02feb06 value. So tightening changed the amount of cal that was getting in before the jump.
• 02feb06: cal polA jumped (turned out to be loose sma connector for cal).
• 10jun05: cal values measured using sky and absorber. backdated to 25may05
• 25may05: new amplifiers installed in cband receiver.
• 24may04 to 08oct04 pola tsys jumping around.. a bias line for the led's inside the dewar was shorting out.
• 16may03: cal values measured using sky and absorber. back dated to 05may03.
• 05may03 cal cable tightened.
• 22apr03 new cal diodes installed.
• 28aug02 horn moved down 1.08" to put phase center at the correct position.
• 22jan01: cal values measured using sky and absorber.

---

Calibration measurements:

Miscellaneous:

19Nov10: Tsys increases when horn gortex fabric cover comes loose.

• Page 1: Tsys vs data for Cband at 5Ghz
• black is polA, red is polb.
• Each minor tick mark is 5 days.
  
• There is some jumping around around 30oct10 to 04nov10
  
• It starts the steady  increase on  07nov10 peaking on 12nov10 at polA=41.4K
• It decreases  back to 25-26K on 19nov10.
  
• On 19nov10 the cover was placed back on the horn (after cleaning out the water droplets).
• Page 2: cband calibration runs: 17oct,15nov,16nov10.
• The dates are color coded
• top: the gains for individual sources are not changing between the dates.
• 2nd: Tsys vs za. the 17oct10 data is about 10k less that the 15,16Nov data.
• 3rd: SEFD: For the same source,the 16nov data is greater than the 17oct10 data by the same amount that Tsys has increased. This shows that the problem was really with the Tsys and not a change in the cal values.

• The gortex fabric cover coming loose at the mouth of the horn caused Tsys to increase by up to 25%.
• The increase, decrease of Tsys was probably a function of the horn temperature and the dew point.
• The receiver has shown other periods where the Tsys has increased and then decreased. It would be interesting to correlate this with the gregorian room temperature and the outside air dew point. It may be that the cover had been loose for awhile.
  

May05 to oct05  fit GAIN CURVES to calib data.  (top)

• Fig 1 shows the az,za distribution for the data. This includes all of the frequencies.
• Figs 2,3,4 plots the gain data and the fit to za.  The freq, fit sigma, and fit equation are printed below the plots.
• Figs 5,6,7 plot the fit residuals (data-fit) vs za.

May05 thru oct05 : System performance data used to compute gain curves.  (top)

• Fig 1 shows the distributions on the dish of the measurements.
• Fig 2: Each frequency is in a different color. Symbols differentiate sources.
• Top: the Gain in Kelvins/Jansky.
• 2nd: Tsys in Kelvins
• 3rd: System Equivalent Flux Density (SEFD)  in Jy. This is the size of a source needed to equal the system temperature. The SEFD does not depend on the cal value  (Tsys/Gain).
• Bottom: The average beam width in arc seconds.
• Fig 3 plots the coma parameter, first sidelobe height below the peak, the main beam efficiency, followed by the main beam + 1st sidelobe beam efficiency. The coma parameter measures the asymmetry in the gaussian beam.
• Fig 3 has the pointing errors in az,za each plotted versus az and za.  Color is used to identify different sources.

Fig 1 4100 Mhz Gain,Tsys,sefd,bmwid. 105 points

Fig 2 4100 Mhz  coma,sidelobes, beam efficiencies

Fig 3 4400 Mhz Gain,Tsys,sefd,bmwid. 106 points

Fig 4 4400 Mhz  coma,sidelobes, beam efficiencies

Fig 5 4500 Mhz Gain,Tsys,sefd,bmwid. 244 points

Fig 6 4500 Mhz  coma,sidelobes, beam efficiencies

Fig 7 4700 Mhz Gain,Tsys,sefd,bmwid. 106 points

Fig 8 4700 Mhz  coma,sidelobes, beam efficiencies

Fig 1 4860 Mhz Gain,Tsys,sefd,bmwid. 242 points

Fig 2 4860 Mhz  coma,sidelobes, beam efficiencies

Fig 1 5000 Mhz Gain,Tsys,sefd,bmwid. 447 points. The source B1645+174 looks like it has a bad cal value. The gain is high, the Tsys is high, but the sefd was normal.

Fig 2 5000 Mhz  coma,sidelobes, beam efficiencies

Fig 1 5400 Mhz Gain,Tsys,sefd,bmwid. 341 points

Fig 2 5400 Mhz  coma,sidelobes, beam efficiencies

Fig 1 5690 Mhz Gain,Tsys,sefd,bmwid. 98 points

Fig 2 5690 Mhz  coma,sidelobes, beam efficiencies

Fig 1 5900 Mhz Gain,Tsys,sefd,bmwid. 98 points

Fig 2 5900 Mhz  coma,sidelobes, beam efficiencies

27sep04 oscillations/jumping of tsys in polA.  (top)

• The top plot shows the total power time series. It has been smoothed to 10 milliseconds. The black plot is polA while the blue plot is polB. The y axis units are Tsys. You can see that polA is jumping around a lot more than polb.
• The bottom plot is the magnitude of the spectrum of the time series (over the entire 90 seconds). The first 20 hz of the spectrum is plotted. The dashed green lines are placed every 1.2 hz. The spectrum has power at harmonics of this frequency.

May03 to Mar04  fit GAIN CURVES to calib data.  (top)

    Gain curves were fit to the cband gain data from 05may03 through 29feb04.  On 05may03 new  cals were installed and the cal cable was tightened. This data is described below.The plots show the gain data (black) and the fits (red) for 4500, 4860, 5000, 5400,5690, and 5900 Mhz. These gain equations were installed on 08mar04.

• Fig 1 shows the az,za distribution for the data. The fit used a 3rd order polynomial in (za-10) and 1az, 2az, and 3az sin, cos terms.
• Fig 2,3 plots the gain data and the fit to za.  The fit equation is plotted with the sigma for the fit (in K/Jy). T
• Fig 4,5 plots the fit residuals (data-fit) vs za.

    The routine gainget() or corhgainget() will now return the cband gain for data after 05may03 from these equations. The coefficients can be found in the ascii file  data/gain.datR9 (this is provided in the AO idl distribution for correlator routines). You can also find a copy of it at AO in /home/phil/idl/data/gain.datR9.

may03 thru feb04 : System performance data used to compute gain curves.  (top)

Fig 1 shows the distributions on the dish of the measurements.

Fig 2 has the Gain in Kelvins/Jansky. This relies on the cals and the source flux. Ths  next plot is Tsys vs za in Kelvins followed by the SEFD  (System Equivalent Flux density) in Janskies / Tsys. At the bottom is the average beam width in arc seconds.

Fig 3 plots the coma parameter, first sidelobe height below the peak, the main beam efficiency, followed by the main beam + 1st sidelobe beam efficiency.

Fig 3 has the pointing errors in az,za, and total (added in quadrature) for the data.

Fig 1 4500 Mhz Gain,Tsys . 275 points

Fig 2 4500 Mhz sidelobes,beam efficiencies

Fig 3 4860 Mhz Gain,Tsys 275 points.

Fig 4 4860 Mhz sidelobes,beam efficiencies.

Fig 5 5000 Mhz Gain,Tsys 567 points.

Fig 6 5000 Mhz sidelobes,beam efficiencies

Fig 7 5400 Mhz Gain,Tsys 566 points.

Fig 8 5400 Mhz sidelobes,beam efficiencies

Fig 9 5690 Mhz Gain,Tsys 292 points.

Fig 10 5690 Mhz sidelobes,beam efficiencies

Fig 11 5900 Mhz Gain,Tsys 292 points.

Fig 12 5900 Mhz sidelobes,beam efficiencies

Aug02 to Dec02 fit GAIN CURVES to calib data.  (top)

    Gain curves were fit to the cband gain data from 28aug02 (after horn focus change) to 30nov02. This data is described below.The plots show the gain data (black) and the fits (red) for 4500, 4860, 5000, and 5400 Mhz.

• Fig 1 shows the az,za distribution for the data. The fit used a 3rd order polynomial in (za-10) and 1az, 2az, and 3az sin, cos terms.
• Fig 2 plots the gain data and the fit to za.  The fit equation is plotted with the sigma for the fit (in K/Jy). T
• Fig 3 plots the fit residuals (data-fit) vs za.

aug02-dec02: System performance:Gain,Tsys,Sefd... using calibration runs.  (top)

Fig 1 shows the distributions on the dish of the measurements.

Fig 2 has the Gain in Kelvins/Jansky. This relies on the cals and the source flux. Ths  next plot is Tsys vs za in Kelvins followed by the SEFD  (System Equivalent Flux density) in Janskies / Tsys. At the bottom is the average beam width in arc seconds.

Fig 3 plots the coma parameter, first sidelobe height below the peak, the main beam efficiency, followed by the main beam + 1st sidelobe beam efficiency.

Fig 3 has the pointing errors in az,za, and total (added in quadrature) for the data.

Fig 1 4500 Mhz Gain,Tsys 241points.

Fig 2 4500 Mhz sidelobes,beam efficiencies

Fig 3 4860 Mhz Gain,Tsys 245 points.

Fig 4 4860 Mhz sidelobes,beam efficiencies.

Fig 5 5000 Mhz Gain,Tsys 279 points.

Fig 6 5000 Mhz sidelobes,beam efficiencies

Fig 7 5400 Mhz Gain,Tsys 273 points.

Fig 8 5400 Mhz sidelobes,beam efficiencies

Fig 9 5690 Mhz Gain,Tsys 35 points.

Fig 10 5690 Mhz sidelobes,beam efficiencies

Fig 11 5900 Mhz Gain,Tsys 35 points.

Fig 12 5900 Mhz sidelobes,beam efficiencies

28aug02 horn moved down 1.08" to put phase center at focus.  (top)

    The cband horn was lowered 1.08" toward the tertiary to place the phase center at the focus (this is explained on the lband focus change page). The source J0738+177 was tracked on 26aug02 before the horn was moved and then again on 28aug02 after the horn positioning. The plots show the results of the focus change.

• Fig 1 shows the gain (K/Jy) before (black) and after (red). The absolute gain values depends on the source flux and the cal. The relative change does not rely on these values. The lower plot shows the relative change in gain (after-before)/before.
• Fig 2 has the gain, Tsys, Sefd, and average beam width for before and after.
• Fig 3 plots the coma, 1st sidelobe level, main beam efficiency, and mainbeam +1st sidelobe efficiency.
• Fig 4 is the pointing error for this source before and after.
• Fig 5 plots the change in pointing error before and after.

    The focus curves done by moving the  platform (bottom plot. cband is bright red color) show that the cband horn was in focus (platform height=1256.35 feet) at za=5 degrees. Below za=5 the platform focused higher (the ray path is too short) while for za > 5 the platform was focusing below 1256.35 (the ray path is too long). Making the ray path shorter by 1 " should have hurt the gain below za=5 and helped it above za=5.
The model of the focus height using AO9 as the reference agrees with the platform focus curves and the data we took here. The model of the focus height with the reflector at the origin (about 2" difference in focus) does not.

sep01 to 27aug02 fit GAIN CURVES to calib data.  (top)

    Gain curves were fit to the cband gain data from 01sep01 (after dish adjusted) to 27aug02 (before horn focus changed). This data is described below.The plots show the gain data (black) and the fits (red) for 4500, 4860, 5000, and 5400 Mhz.

• Fig 1 shows the az,za distribution for the data. Because of the incomplete az coverage, the fit was only done to  za.
• Fig 2 plots the gain data and the fit to za.  The fit equation is plotted with the sigma for the fit (in K/Jy). The quadratic and cubic terms of the fit should only be used for za >= 14 degrees.
• Fig 3 plots the fit residuals (data-fit) vs za.

sep01-aug02: System performance:Gain,Tsys,Sefd... using calibration runs.  (top)

Fig 1 has the Gain in Kelvins/Jansky. This relies on the cals and the source flux. Ths  next plot is Tsys vs za in Kelvins followed by the SEFD  (System Equivalent Flux density) in Janskies / Tsys. At the bottom is the average beam width in arc seconds.

Fig 2 plots the coma parameter, first sidelobe height below the peak, the main beam efficiency, followed by the main beam + 1st sidelobe beam efficiency.

Fig 3 has the pointing errors in az,za, and total (added in quadrature) for the data.

Fig 1 4500 Mhz Gain,Tsys 355 points.

Fig 2 4500 Mhz sidelobes,beam efficiencies

Fig 3 4860 Mhz Gain,Tsys 353 points.

Fig 4 4860 Mhz sidelobes,beam efficiencies.

Fig 5 5000 Mhz Gain,Tsys 427 points.

Fig 6 5000 Mhz sidelobes,beam efficiencies

Fig 7 5400 Mhz Gain,Tsys 420 points.

Fig 8 5400 Mhz sidelobes,beam efficiencies

Fig 9 5600 Mhz Gain,Tsys 71 points.

Fig 10 5600 Mhz sidelobes,beam efficiencies

Fig 11 5900 Mhz Gain,Tsys 71 points.

Fig 12 5900 Mhz sidelobes,beam efficiencies

22dec01: sefd, pointing errors.  (top)

 home_~phil