26 June 2001
Work on the azimuth track is progressing well and we expect to resume astronomical commissioning on July 16, as scheduled. Work by the contractor, Lockheed-Martin, to install the new bolts that hold down the track wear strips was completed on June 8. The old bolts of 1-inch diameter were replaced with new bolts of 1.5 inch diameter, and the total number of bolts in each track segment was nearly tripled. Over 1700 bolts were installed, which first required that holes be drilled and tapped (see photo below). The contractor is now re-aligning the azimuth wheels, which is the final step in the procedure. The re-alignment is about half completed at this writing and should be finished by mid-July.
Both the contractor and the Observatory staff have used the time during the azimuth track work to address as many other projects as possible. The Observatory staff has been re-setting the corners on the reflector panels following the surface adjustment to take out the errors measured by photogrammetry. About 1700 of the 2209 corners have been adjusted, and the work should be completed by mid-July. Other work has included cabling and installation of telephones, listening stations, and PA horns on the structure, programming and test observations with the GBT Spectrometer, and many other tasks. The contractor has used the time for a scheduled replacement of several of the azimuth wheel bearings, to continue painting of the structure, and to work on items on the punch list.
The current schedule calls for astronomical commissioning to resume on July 16 with some testing with the prime focus receiver, followed by commissioning of the L-band receiver and the GBT Spectrometer.
GBT Azimuth Track with new 1.5-inch bolts installed.
P. R. Jewell / R. M. Prestage