History of pointing residuals

The following links show plots of the rms scatters in daz and del for each night's data, plotted as a function of date. Datasets with less than 10 data are shown by the smaller dots, those with N>10 by the large squares. The dashed line is drawn where the value of the residual is 2.0". The distributions of these rms values (and the mean and annual scatter about this mean) are shown in the lower frames in each case.

Notes :

• 1997 - RxA2 - good results, but may be dominated by small datasets, which often comprise repeated measures of bright sources closely spaced in time. (Large datasets too have their own peculiarities and often contain odd results that could be justifiably removed a posteriori)

• 1998 - SCUBA - a preponderance of low daz scatters; perhaps more in accordance with the values obtained during dedicated pointing runs (approx 1.7").

• 2000 - SCUBA - note the increase in scatter immediately following the introduction of the new TCS in August, and the subsequent recovery.

• 2004 - note the v.good azimuth residuals (and the gaps due to the unavailability of SCUBA).