The making of 26 inch Cassegrain - 23, Semi-first Light
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- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
The making of 26 inch Cassegrain - 23, Semi-first Light
Dear ATMers,
Although still in its raw state, the 26 inch Cassegrain managed to carry out its semi-first light on Friday, to celebrate to oncoming Mid Autumn Festival.
We chose this night for good reasons - first of all it’s a Friday night and student didn't need to go school next morning. Furthermore the primary mirror is still not yet silvered giving it the right amount of reflectivity to give the moon a very comfortable luminance, not to hurt students' eyes. Last but not least it gave a very good chance to test the whole operation of the telescope to see if there were any flaws. Actually there are flaws.
1. The telescope is too heavy to be pushed by hand. Such a big inertia is too difficult to be handled with by mere human flesh. ServoCAT + Argo Navis will be added very soon.
2. The cover for primary mirror is stupid. It could be be taken out from themirror box once the telescope is assembled. It has to be redesigned.
3. The diagonal cage is too heavy. We have to remake it to reduce the weight to ease the assembling and disassembling job.
4. The secondary mirror has a diameter of 10 inches (!!!). The secondary shadow inside the eyepiece view is noticeable even at power of 160X. This has no cure, unfortunately.
5. Painting of the whole structure has to be done ASAP otherwise humidity will eat up the wooden structure soon.
Despite all these shortcomings we were especially pleased with the Nasmyth focus of the telescope. It served what it is intended to - the eyepiece is always at the right height so that everyone can look through with ease, no matter where the telescope points to.
Oh one thing I nearly forget to tell - how it was like to view the moon with the biggest telescope in Hong Kong ? Well it's very solidly 3-D and the lunar surface is so full of details. The view is crisp.
The students were shocked by the detailed view of the lunar surface and also, by the sheer size of the scope. Once again astronomy was promoted among youngsters.
Best regards
Chan Yuk Lun
26 September 2015.
Although still in its raw state, the 26 inch Cassegrain managed to carry out its semi-first light on Friday, to celebrate to oncoming Mid Autumn Festival.
We chose this night for good reasons - first of all it’s a Friday night and student didn't need to go school next morning. Furthermore the primary mirror is still not yet silvered giving it the right amount of reflectivity to give the moon a very comfortable luminance, not to hurt students' eyes. Last but not least it gave a very good chance to test the whole operation of the telescope to see if there were any flaws. Actually there are flaws.
1. The telescope is too heavy to be pushed by hand. Such a big inertia is too difficult to be handled with by mere human flesh. ServoCAT + Argo Navis will be added very soon.
2. The cover for primary mirror is stupid. It could be be taken out from themirror box once the telescope is assembled. It has to be redesigned.
3. The diagonal cage is too heavy. We have to remake it to reduce the weight to ease the assembling and disassembling job.
4. The secondary mirror has a diameter of 10 inches (!!!). The secondary shadow inside the eyepiece view is noticeable even at power of 160X. This has no cure, unfortunately.
5. Painting of the whole structure has to be done ASAP otherwise humidity will eat up the wooden structure soon.
Despite all these shortcomings we were especially pleased with the Nasmyth focus of the telescope. It served what it is intended to - the eyepiece is always at the right height so that everyone can look through with ease, no matter where the telescope points to.
Oh one thing I nearly forget to tell - how it was like to view the moon with the biggest telescope in Hong Kong ? Well it's very solidly 3-D and the lunar surface is so full of details. The view is crisp.
The students were shocked by the detailed view of the lunar surface and also, by the sheer size of the scope. Once again astronomy was promoted among youngsters.
Best regards
Chan Yuk Lun
26 September 2015.
- 附加檔案
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- Observing in the Nasmyth focus of telescope - a comfortable height.
- 102.jpg (243.06 KiB) 已瀏覽 5802 次
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- Semi-first light of the 26 incher.
- 100.jpg (324.23 KiB) 已瀏覽 5802 次
最後由 Chanlunlun 於 週日 27 9月, 2015 00:15 編輯,總共編輯了 3 次。
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QUOTE
Johnny Sir 寫到:
Once if it “to show up” in PTC someday ~WOW!
UNQUOTE
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Johnny Sir,鏡神大哥提及因望遠鏡的體積太大無法離開皇仁書院天台,相信閣下的願望落空了 ...
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QUOTE
lawrencemok Sir 問到:
With scope that big,I guess it has to stay in school?Can't wait to visit it in coming open day.
鏡神大哥回覆:
Yes you are telling the truth. It won't leave the roof of QC. Come at open day and see.
UNQUOTE
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引言貼文來源:
http://www.hkastroforum.net/viewtopic.p ... Chanlunlun
QUOTE
Johnny Sir 寫到:
Once if it “to show up” in PTC someday ~WOW!
UNQUOTE
----
Johnny Sir,鏡神大哥提及因望遠鏡的體積太大無法離開皇仁書院天台,相信閣下的願望落空了 ...
----
QUOTE
lawrencemok Sir 問到:
With scope that big,I guess it has to stay in school?Can't wait to visit it in coming open day.
鏡神大哥回覆:
Yes you are telling the truth. It won't leave the roof of QC. Come at open day and see.
UNQUOTE
----
引言貼文來源:
http://www.hkastroforum.net/viewtopic.p ... Chanlunlun
-
- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
-
- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
We used to travel along with a 30 incher. The 30 inch telescope was actually once transported to Cheung Chau but weather was cloudy that night.Steve 寫:
其實大過廿四吋都幾難運送到夠黑的地方用。
During the second star trip to Water Mouth the 30 inch primary mirror was broken into pieces by a careless student. We had very clear night that night together with a broken telescope.
Actually the 30 inch telescope, if it still survives, could be brought to PTC without very big problem, given that sufficient manpower is provided.
How was it like to view through a 30 incher ? I have no idea because the the mirror got no chance to collect photons from stars.
-
- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
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