Summary
Changes are made to

DZT_COEFF - the slope of the relationship between Z and Tmean
• XA - the X elevation focus curve gradient X = XB + XA*cos(el)
• TF - the telescope flexure term of the pointing model

Changes were made to some of the SMU parameters and collimation offsets on 20080104. The data analyzed here have been acquired since that date:

   FE      Axis       N      mean    +-       Notes & Trends
  ----    -----      ---    ------ ------     ---------------------------
  RxA       Z         8     -0.02   0.14          (0 < Tmean < 7)
            X         4     -0.14   0.09     
            Y         4     +0.04   0.11     

  HARP      Z        82     +0.05   0.16      1   (0 < Tmean < 10)
            X        24     -0.06   0.13      2
            Y        24     -0.09   0.10

  Trends : 1 HARP_Z = (+0.027 +- 0.007)*Tmean    s.d. 0.15
           2 HARP_X = (-0.71  +- 0.09 )*cos(el)  s.d. 0.07
          

Both noted HARP trends confirm those seen last October. Corrections are made (25 Jan 2008) as follows:

• DZT_COEFF from +0.090 to +0.110
• XA (the "X elevation focus curve gradient" ) from 5.791 to 5.080

Pointing
In the period UT20080110-25, only 16 RxA data have been logged. The show no significant systematics w.r.t. the current model (that of 20070412, as modified in December 2007 for collimation changes resulting from the SMU engineering). Formal collimation offsets (CA,IE) are (-1.8",+4.6") and rms scatters in (dS,dZ) are (1.1", 3.3"). This latter figure is so similar to the HARP raw performance in elevation that one wonders if there is a linkage via the X-focus problem seen above.

HARP
In the same period, 183 HARP data have been logged and are shown below:

Mean collimation offsets (CA,IE) are (+14.9", +36.3"), which compare well with the current relative collimation offsets in /jac_sw/itsroot/src/harpb/XML/instrument_harpb.ent of (+15",+35"). RMS scatters in (dS,dZ) are (1.9", 3.7"). There is a clear systematic in the dZ-vs-Z plot (centre panel), as seen previously, and a full 7-parameter fit reduces (dS,dZ) to (1.8",3.0") mainly by a 7-sigma change in TF from -9.8 to -19.3 ("/airmass !?). This change also is made today.