Pointing model12. feb01

[last mod 27mar01]

(26mar01 .. this is prelimary stuff....)

Feb01 model12 using sband narrow at 2380 and 2290.

background:

Main reflector surface measured (3000 targets on main support cables) dec00.
Tiedown cables adjusted: dec00-jan00
jan00 Gregorian dome wheel bearings break. Large beam 20 feet from center bearing on azimuth arm raised to jack up dome
Feb01,Mar01 model data collected during the day : 10am to 8pm .
1603 points were used for the model.

Input data to model (.ps) (.pdf)
The data for the model is taken with the previous model11 in place. Figures 1-4 show these errors. Figures 5 and 6 remove the model 11 correction and show the raw telescope pointing error. All errors are great circle arc seconds.

Fig. 1 is the azimuth zenith angle coverage for the input data.
Fig. 2 is the pointing error (za error top, az error bottom) plotted versus azimuth. This is relative to model 11.
Fig. 3 plots the same model 11 errors versus zenith angle.
Fig. 4 is the magnitude of these errors plotted versus azimuth, za. 1 tick mark is 10 arc seconds.
Fig. 5 has the raw az,za errors plotted versus azimuth. The model 11 correction has been removed. Model 12 will be fit to this data set.
Fig. 6 shows the same raw errors plotted versus za.

Model12 fit residuals (.ps) (.pdf)
The model is fit to the rawerrors data. An encoder table spaced every .5 degrees in za is computed for azimuth and zenith angle errors and then removed. The final residuals are great circle errors. The telescope must move in that direction from the computed position to point at the source.

Fig. 1 plots the residuals versus za for the azimuth and za errors. The encoder table has not yet been removed. The computed encoder table is overplotted in red.
Fig. 2 plots the azimuth and za (rawErrors - ( model + encoderTable) ) residuals versus za. The rms errors are:

3.65 asecs za rms
5.61 asecs az rms
6.69 asecs model12 rms (combined in quadrature).

Fig. 3 plots the azimuth and za (rawErrors - (model + encoder table) residuals versus azimuth.
Fig. 4 plots the magnitude of the residuals (model + encoder table) versus azimuth and za. 1 tick mark is 5 asecs (Fig. 4 of the input data was 10 asecs per tickmark).

Verifying the model (.ps) (.pdf)
A few sources not included in the model were tracked to verify the model. This was done during the day with the sband receiver. The sources include J0242+110, J0403+260, J2316+040, J0137+331 (3C48), J0318+164 (CTA21), and J0603+219.The 325 points had an az rms of 6.56, a za rms of 3.50 giving a total rms of 7.4 asecs.

Figure 1 shows the az,za coverage for sband (CTA21 was tracked on two separate days).
Figure 2 plots the za error, az error versus az.
Figure 3 plots the za error, az error versus za.
Figure 4 plots the za error, az error by source.
Figure 5 is an arrow plot versus az,za of the errors (5 asecs = 1 tick mark).

To compute the azimuth and zenith angle offsets for the other recievers, CTA21 was tracked with sbn and then with lbn,lbw,cband and 430. The offsets in azimuth and za were adjusted so that the average error was the same as that for sband narrow. J0602+219 was tracked with sband narrow and the 610 and 430 receiver.

figure 6 shows the errors for sband, lbn, lbw, and cband. The sbn, cband zaerror have a large difference rise to set. Lbw az error does not track lbn very well.

processing: x101/model/model12/proc/doit.pro, domodel.pro, verify.pro

plotting  : x101/model/model12/proc/pltinp.pro, pltmodel.pro, pltver.pro

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