A central bearing load adjustment was performed on 13 July 2005. Tomas Chylek reports "The load distribution between the central bearing and the rollers has been kept at 85%/15% of the total antenna weight". Full results are available here.

Inclinometry was then done as follows :

    Datasets  El Dirn     HST     mean leg temperatures   Humidity
                          start     start   middle   end       %
  ( 20050625  88  cw      10:15      9.4     10.5   11.5      35 )
    20050713  88  cw      15:00      7.0      8.5    9.5      50

All inclinometry and temperature data channels look OK, although Ch1 needed a few extra minutes (and some cable un-re-plugging ?) to join in the fun. Ch13 - the #1 strain gauge - is still not functional.

The difference between the CW model resulting from these new data and the previous one of 25 Jun is shown below:

• No surprise : there are some large-r-than-normal systematic differences.
• The differences in (F1,F2,F3) are described by rms scatters of (0.84", 0.35", 0.43") c.f. (0.54", 0.20", 0.34") previously.
• The new CW model was merged with the (CW-CCW) template to create a new hybrid track model, which was installed at HST 18:00 on 13 Jul 2005.
• The symmetry (defined here) is much improved from recent times, while the wheel loads - as judged from strain gauge No.2 only - are ~20% larger than last time.

All-sky Pointing
This is the first time in years that a pointing model has been determined using a FE other than SCUBA; the weather dictated RxA. 30 pointing measures were recorded in ~4 hours and the raw residuals w.r.t. the old model are shown below:

There is surprisingly little in the way of systematics : perhaps a 'bowing' in the del-vs-el plot (central panel); but not the usual daz-vs-el trend (upper central panel) indicative of a change to the azimuth encoder zero-point, as usually occurs after a CBLA.

The data were run through the TPOINT analysis package. The before and after plots are shown below:

RMS residuals after the fit are (1.4", 2.4") in (daz,del). This is not at all bad considering the poorish weather we've had recently. Tau this night was pleasingly stable, at ~0.13 throughout, and although the local humidity stabilized also, at ~20%, that was not until after the pointing was finished (10pm); variations up to 70% characterized the first few hours of the night - which might add refraction noise to the elevation performance.

The new pointing model was installed at ~22:10 HST.

20050715 UT
Large collimation offsets reported : I had forgotten to set RxA collimations to (0,0). (blush). Now done, with RxB and RxW collimations adjusted equally. Offsets w/RxA & B now ~(0,0), and azimuth performance good (rms ~1.5"), but elevation performance erratic. Solution sought.