The J2-K2 differences are more tightly grouped and show a small linear trend in dx with hour angle. The other two band-difference pairs show both a greater dependence on hour angle and more scatter. Figure 4 presents the same plots w.r.t. All four figures to this point are consistent with flexure driven by telescope orientation but also dependent on it's last position. This is further illustrated by Figure 5 which plots a history of dx vs dy for each band-difference pair throughout the night.
Dotted lines connect the points in scan order.
In each case there is a single point which lies mid-way between the two groups. This point corresponds to scan 36 which is of considerable interest. It appears thatin most cases the large shifts occur during the slews between scans, but in this case much of the shift appears to have occurred during the scan, rather than the slew. The latter can be fitted out, the former cannot. The current model in PosFrm assumes a single 2D linear transformation defines the relationship between each band pair over a scan.