Mirror aluminisation

The NOT primary and secondary mirror were realuminised on the 27th of May 2002. The previous aluminisation took place in May 1997 for M1 and June 1995 for M2. The whole procedure started by dismounting the mirrors on the 24th of May, and the mirrors were transported back to the NOT on the 29th of May. While the mirrors were out, the telescope center section was machined to improve roundness and centering of the primary mirror.

Alignment was done on the 30th of May, and a report on the alignment procedure is currently being made.

The throughput was tested with ALFOSC and StanCam on the 31st of May. Results for StanCam show the following sensitivity improvements:

Table 3: Sensitivity improvement

Filter	After/Before
U	1.59
B	1.51
V	1.36
R	1.32
I	1.29

Also, the position of the top unit of the telescope was checked and corrected.