The last two weeks have seen rather poor weather, but last night tau_225 fell to ~0.2 at last, so its pointing data seemed worth presenting. (This is the first update since 25 Sep). The results of fitting the TPOINT parameters CA and IE and their errors (dS,dZ) are quoted:

    UT dates    Rx   No. of points     CA    dS      IE    dZ   Notes
   -----------  --   -------------   -----------   -----------  -----
   20061023      A        15         -2.8 +- 2.6   -7.6 +- 2.7

The rms errors are large, but unsurprising, given the weather. (CA,IE) are to be compared with the current collimations for RxA of (0,0).

The increasingly -ve values of IE were previously speculated to correlate with the steadily dropping nighttime temperatures, but the JCMT engarchive has been unavailable since the 15 Oct earthquake, so such a correlation cannot be tested just yet. (UKIRT air temperatures at midnight are ~4 degrees cooler than an month ago).

However, no changes are contemplated to the collimations just now.