Updated telescope model

As a result of excellent weather and pointing restricted to point sources, and despite having to reconstruct the data from the second shift after the pointing.log file somehow got lost, the data from last night reveals a trend of daz with elevation that has now been removed.

The plot below shows the data from last night. N=35, although the last 2 data are clearly affected by daytime temperature effects and are dropped from the analysis.

Immediately noticeable is the trend of azimuth residual with elevation, but at a lower level is also a trend of the elevation residual with time - meaning, presumably, with temperature. For all but the last 2 data, this trend is removed by a relationship of the form

       del  =    1.01  *  0.5*(Tf + Tb)
              +- 0.24

   where Tf and Tb are the mean temperatures of the front and back legs. 

The resulting (temperature-corrected) data were then run through the FIT9 program to deduce changes to the 7 parameters of the telescope model that minimize the residuals. The following changes :

       parameter #   1     2     3      4      5     6     7
                   0.2   0.1  -7.3   -14.9  -12.7   0.0   0.1  

gave the following pointing residuals :

The pointing model has been updated and should behave as above - with rms scatters in (daz,del) of (0.9", 1.0"). If it does not please file a fault report and/or let me know.