Reflector adjustments mar01 (M_TD2)

04dec01
     The main reflector tiedown cables were adjusted a second time in mar01 and then measured. The az/za plots show the  errors in mm normal to the reflector surface. The measured points on the reflector surface go all the way to the edge of the dish so the zenith angle goes from 0 to 34 deg. The circles on the plot are placed every 8 degrees in za. Data is plotted for jan01 after the first adjustment and for mar01 after the second adjustment to show the improvemetns.  The figures are:
  1. Figure 1 shows the az,za coverage for the measured targets. Top is the measurement of jan01, bottom is from mar01.
  2. Figure 2: The surface errors measured in jan01 after the first set of adjustment were completed. The arrow length is proportional to the error. 1 tick mark is 3 mm. The angle is also proportional to the error. +/- 180 is +/-  10 mm. Errors larger than 10 mm are clipped to 10 mm and +/- 180 degrees.  The statistics in the table include all points except for 10 points with error > 30 mm.
  3. Figure 3: The surface errors measured mar01 after the seconed round of adjustments.  The arrow lengths, angle, and clipping are the same as Figure 2.  The statistics in the table include all points except for 3 points with error > 30 mm.
  4. Figure 4: Shows the reflector errors after the mar01 adjustment. The arrow length is proportional to the error (but the scale is changed so 1 tick mark is 2 mm). The angle of the arrow shows the fractional change in error from the jan01 measurement:

    5. (errorBefore-errorAfter)/errorBefore - 1. Errors < 1 mm have been set to 0. Errors > 30 mm have been clipped to 30 mm. Anything black was turned too far. Anything red was not turned far enough. You can see the large errors in the center (red) that point at -60 degrees. These are on the new panels that have no adjusters beneath them so their error did not change. The large errors at -120 degrees (right side of plot) were turned the wrong direction.
  5. Figure 5: jan01: The rms. error, mean error, minimum error, and maximum error are computed for each main cable (running north/south). These values are plotted versus the east/west distance from the center of the dish (the cables are spaced every 25 feet). The large spikes in the center cables are coming from new panels covering the opening in the center (see figure 6). The average shows a slight curvature toward the left edge. All the data points were included.
  6. Figure 6:  mar01: This is the same plots as figure 4, but for the data measured in mar01. Notice that the vertical scales have changed. i All the data points were included.
  7. Figure 7: jan01 data.This shows the bad points on the new panels that cover the hole in the center. The 7 strips are the 7 east/west rows closest to the center (limited to +/- 300 feet from the center). The average position of a strip is its east/west distance in feet from the center of the bowl. The offset from the average position is the error in mm. The largest error is on the blue strip that goes through the center of the dish. It has an error of about 145 mm.
  8. Figure 8: mar01 data for the strips through the new panels at the center of the dish.
processing: x101/dish/M_TD2/mar01.pro for a description
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