A CW run with the 'fixed' TMU inclinometer was made during the morning :

    Datasets El Dirn     HST     mean leg temperatures   Humidity
                        start      start   middle   end       %
  ( 20020428 90 cw       20:30      6.8             5.8     100 
    20020429 90 cw       20:54      3.8      3.7    3.3     100 )
    20020501 90 cw       06:40      0.6      1.2    2.4      40

The temperature data from the fixed TMU inclinometer seem OK again (!?) so data were processed into a track model in the conventional way. The model resulting is compared below with the model from the 29th :

• Justin's 'spikes' are manifest.

• The mess in quadrant 5 (azimuths >360) may reflect electrical noise from the activity of the daycrew, who would have arrived in the building at about that time. As seen before the spikes measured in q1 are not reproduced in q5, at least not with the same amplitude. The temperature increases through this period : it may be speculated that the thermal threshhold for Justin's theory today is around 2^oC -- as judged by the mean antenna leg temperatures. This cannot be absolute, because 5" spikes were recorded on 24th Apr when the mean antenna leg temperature was 4.7. The theory requires that a large thermal differential exist between the upper antenna and the pintle bearing in the plinth, so these recent results require suitable plinth temperature variations. No measure of the temperatue in that part of the building is yet available.

• Updates have been made to the plots of symmetry and strain gauge data. Both show the expected excursions fron normalcy.

• The detail below shows the difference in the Y-axis data between the two datasets used in the plot above :
  

  The blue vertical lines show the locations of the track joints. The model terms F1 & F2 in the top plot are a mix of the data from the inclinometers on the two A-frames, whereas it is clear from the Y-axis data here that the larger contribution comes from the left A-frame. The wheels involved in the spikes at azimuths ~13, 37 & 64 are 2 (right, rear) & 4 (front, left), so in these cases the 'culprit' is wheel 4.