the first star test of the 24 in telescope

[Chanlunlun]

Dear ATMs,

Thanks for the continuous fine weather the first star test of the 24 inch telescope was carried out last night, using a UWV 6.7 mm eyepiece, giving a 313X magnification. The result obtained will be used for retouching the mirror at once.

The test reviewed the fact that the mirror is under corrected a little bit although it shows a null figure in the Offner tester. This is by no means surprising since there must be error, one form or the other, exists inside our Offner tester. Computer simulation for light ray tracing will be commenced at once to locate a more optimized setting for the Offner tester.

Since the spherical aberration present is very mild the retouching process should be carried out in utmost care. A figuring process more than 10 minutes will probably overdo the job. Hence the mirror will be figured directly under star light, then reconfirmed by the re-calibrated Offner tester. This is being more safe-proof than the job carried out in the reverse order.

This is the beginning of the end. The birth of this newly fabricated large telescope will not be long away.

Best regards
Chan Yuk Lun
20-4-2004