A full cw/ccw inclinometry run was performed on May 15th. These results showed indications that one of the wheels of the telescope is lifting off the track. This was a imminent possibility given the reduced loading on the wheels (particularly wheel 4) mentioned in the previous report.

• The differences between the (CW) models derived from the new data and data taken on 2nd May are shown below:
  Click for larger image

• The formal differences in (F1,F2,F3) between these data are described by the rms scatters of (1.65", 1.15", 0.70") although the data are rendered useless by the large 5" 'spikes', which dominate.

• The blue vertical lines on the plot show the locations of the wheel-joint interactions and it is at these positions that the spikes appear. These spikes have previously been identified as the result of insufficient loading on the wheels (click here for the theory).

• This profile has been observed previously, first in 1998/1999 and again in 2002. (see 19981207, 20020225 and 20020424).

• The new model was not installed. The azimuth ranges away from the spikes showed little deviation from the previous model so observing continued under caution.

• The strain gauge data for the one remaining channel shows a further reduced loading on wheel 4 (at azimuth ~100°) and a strong asymmetry between the left (w3 & w4) and right (w1 & w2) hand side of the telescope.
  

• A central bearing adjustment is now essential to redistribute the weight, however the left-right asymmetry is expected to remain until the return of SCUBA2 on to the telescope.