Poor weather allowed us to gather nighttime CW runs :

    Datasets El Dirn     HST     mean leg temperatures   Humidity
                        start      start   middle   end       %
  ( 20020213 90 cw       00:00     -0.2      0.0    0.1      80 
    20020218 60 cw       20:59      3.7      3.7    3.6     100 )
    20020224 90 cw       03:38      1.1      1.4    1.6     100
    20020225 20 cw       02:47     -2.3     -2.5   -2.5      90
    20020303 90 cw       10:42     -1.8      0.0    1.5      25

• The new data at are again of full amplitude - i.e. showing no sign of the 'small-amplitude' syndrome captured on 17 Oct.

• The difference between the model resulting from the 20020224 data at el=90 using the 'fixed' TMU inclinometer, and those from 13 Feb is shown below :
  

• The formal differences in (F1,F2,F3) between these data are described by the rms scatters of (0.66", 0.43", 0.35") c.f. (0.55", 0.20", 0.46") previously.

• However, this does not tell the whole story, since the data contain features frighteningly reminiscent of the 'spikes' that plagued inclinometry data through the late 1990s : see the first of the 'old' faults. The azimuths of the spikes seen here are 13, 37, 40, 64, 147, 193, 217, 220 and 244, corresponding to wheel-trackjoint interactions involving wheels 2, 4, 2, 4, 3, 4, 2, 4 and 2, respectively.

• The 'spikes' were previously exacerbated by cold temperatures, but the conditions at this time were quite benign.

• The new model was not installed.

• The difference between the model resulting from the 20020225 data at el=20 using the 'tiltable' inclinometer and the 20020224 data using the 'fixed' TMU inclinometer is shown below :
  

• The formal differences in (F1,F2,F3) between these data are described by the rms scatters of (0.91", 0.70", 0.73") although again the data are rendered useless by the 'spikes', which are more prevalent, but no stronger, than they were yesterday.

• The data were also analysed for symmetry properties -- see the time line -- and for the strain gauge measures. The data show a striking deterioration in both indicators, suggesting a drop in wheel loading to values as low as any in the past 3 years. A central bearing load adjustment may be needed.

03 Mar 2002
An attempt to monitor the persistence of the spikes was somwhat hampered by the abnormal signal from the TY inclinometer (Ch2) on 03 March - see plot. However, the data were still useful enough; the differences in the model parameters F1 & F2 are plotted below :

No sign of the 'spikes' in the above sense is seen : the single negative spike in F1 at azimuth ~150 is narrow, and is likely an electronic error.

Updates to the plots of symmetry and strain gauge data show no confirmation of the low wheel loading seen above.

The central bearing load adjustment is progressing today as scheduled . . .