A summary of the results presented on 18 March :

• The pointing residuals obtained when the track model is disabled are well matched by the predicted residuals, as derived from the inclinometry formalism:
  • (yaw)     F1 = g_LLY + g_RLR
  • (roll)     F2 = g₂TX
  • (pitch)   F3 = g₃TY
  • daz = F2*sin(el) - F1*cos(el)
  • del = F3
  Somewhat by default, we have been using g_L = -g_R = -g₂ = -g₃ = 1, and the expectation was that tracking data would help finesse the values of these coefficients.

• The earlier analysis of tracking residuals obtained when the track model was enabled suggested that perhaps the F2 term of the track model was not being applied at all !

To test this, the current model was modified as shown below :

  ......
  ......
  177.29   -4.04    3.65   -2.67
  177.49   -3.37    4.15   -2.22
  177.69   -3.51    4.15   -1.99
  178.09   -3.37   44.17   -1.75
  179.09   -2.74   44.65   -1.17
  180.09   -1.49   44.90   -0.46
  181.09   -1.10   44.83   -0.35
  182.09   -0.62   44.99    0.03
  183.09   -0.19    4.89    0.59
  184.09    0.04    4.68    0.79
  185.09    1.19    4.77    1.17
  ......
  ......

. . . adding 40" to the F2 term near southern transit. On UT 20030404, 3c279 was tracked using SCUBA through this azimuth range. The observed pointing residuals are shown below :

The 40" modification to F2 generates a +15.3" excursion in daz, (stimulating the -15.3" recovery recorded here) confirming that the track model is being applied. However, the size of this excursion is that expected if the F2 contribution to daz was F2*cos(el) [ 40" x cos(64.4) = 17.3", actually ], whereas it's supposed to be sin(el) !

UT20030409

After adding -40" to the F1 term of the default track model, similar tracking data were obtained on UT 20030409 :

The -40" modification to F1 generates a +17.0" excursion in daz, stimulating the -17.0" recovery recorded here. By comparison with the expected excursion size of 40cos(64.4) = 17.3" this confirms that, vis-a-vis F1, the track model is being applied as expected.

En passant the elevation tracking data through this period of 0.5 hours, and through transit, show no sign of any transit effect, with an rms scatter of 0.9".