24 inch telescope saw its first light

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Chanlunlun
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文章: 3828
註冊時間: 週四 09 10月, 2003 21:06

24 inch telescope saw its first light

文章 Chanlunlun » 週一 21 6月, 2004 14:31

Dear ATMs,

Finally the 24 inch telescope saw its first light on 19th June, 2004. The weather was still good at day time but deteriorated during night at Water Mouth. Anyway we still managed the telescope to take views of some deep sky object despite of the clouds overhead. All object were seen after thin ( or thick ? ) clouds. All observations were done by using a UWV 14 mm giving a magnification of 150X.

1. M65, M66 – marginally seen, even with a 24 inch aperture.
2. Omega – if you think that the view must be terribly magnificent then you were wrong. It should be but not through the clouds. The Omega looked as if we were using a 2.4 inch refractor instead of a 24 inch reflector.
3. M4 – we are pleased that the globular cluster were resolved down to its center, but it was rather dim at the eyepiece, thanks to the clouds.
4. M51 – we saw two blobs of light only and nothing else. Just like using a 4 inch telescope.

However the meaning of first light also contained the idea of commisioning the equipment. We are particularly satisfied with the followings :-

1. The whole equipment is mobile enough up to our satisfaction. Two men were enough to take it onto MTR and taxi without major difficulties.
2. There are no sign of astigmatism of the mirror under star viewing showing that the 18 point floating cell is performing perfectly.
3. The stars are round and sharp, at about 200X, showing that the students were doing a good job in figuring the mirror.
4. The coma of the f/3.4 paraboloid is severe theorectically. However a LVW 22 mm eyepiece corrected for the coma and field curvature of the mirror. The star both at center and edge of field are round and pin-point almost altogether. It seems that the Vixn LVW22 mm should be included as a standard accessory for the 24 inch.
5. The whole equipment could withstand moderate wind breeze.

We were disappointed by the followings :-

1. The silk velvet, which was supposed to protect the silver surface of the mirror, destroyed silver surface instead by introducing grey spots all over the silver coating. It seemed that the red dye of the silk velvet contained sulphur compound. So the best way to protect the silver surface is to let it in touch with nothing.
2. There was a mysterious high frequency vibration of the whole structure. Clearly it was not coming from the mechanical side as the whole structure. Given its dimension, the structure cannot support such a high frequency vibration. Later analysis concluded that this strange vibration comes from the reflection of the shock wave from the primary mirror. A little stabilizer put in touch with the mirror surface solved this problem.
3. The total weight of the telescope was about 65 lbs. However with the suitcase, wooden box for mirror and other accessories the total shipping weight tallies to about 100 lbs. We must reduce the shipping weight for comfort of transportation.
4. The color scheme of the equipment is being not elegant enough. May be in the future we need to paint the telescope again..

So far the power of the 24 inch telescope is not yet fully released due to bad weather. We all hope that a second chance for employing the 」beast」 up to its fully capacity will come soon. I hereby also make apology to Mr. Subaru, Mr. David_kmng and Raymond for packing up the whole equipment too soon to let them have a glance at it.

But I am being confident that a second chance may appear in the every near future.

Best regards
Chan Yuk Lun
21-6-2004

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Wah!
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文章 Wah! » 週一 21 6月, 2004 15:01

How about bringing it to Yuen Long Astrofarm next time?

Chanlunlun
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註冊時間: 週四 09 10月, 2003 21:06

文章 Chanlunlun » 週一 21 6月, 2004 15:14

Wah! 寫:How about bringing it to Yuen Long Astrofarm next time?
Dear Mr. Wah!,

Of course it could be arranged, if it can be beneficial to sufficiently large amount of people.

Best regards
Chan Yuk Lun

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Wah!
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文章 Wah! » 週一 21 6月, 2004 19:24

The weather in Yuen Long on 19th was not so bad as Shui Hao.
I think we will have higher chance to have fine weather in Astrofarm rather than Shui Hao.

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豆豸苗
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註冊時間: 週六 28 6月, 2003 02:29

文章 豆豸苗 » 週一 21 6月, 2004 20:16

咁不如搵次邀請陳 sir 帶支鏡來農莊啦. ^^

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Subaru
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文章: 6666
註冊時間: 週三 02 7月, 2003 19:27

Re: 24 inch telescope saw its first light

文章 Subaru » 週二 22 6月, 2004 14:29

Chanlunlun 寫:I hereby also make apology to Mr. Subaru, Mr. David_kmng and Raymond for packing up the whole equipment too soon to let them have a glance at it.

But I am being confident that a second chance may appear in the every near future.

Best regards
Chan Yuk Lun
21-6-2004
No need to sorry. It's sky observing's nature that 8 out of 10 sessions are without favourable results.

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Subaru
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文章: 6666
註冊時間: 週三 02 7月, 2003 19:27

文章 Subaru » 週二 22 6月, 2004 14:30

豆豸苗 寫:咁不如搵次邀請陳 sir 帶支鏡來農莊啦. ^^
假如在港島東出發而又就到時間的話, 在下可幫手運載.

HK.Raymond.Tse
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文章: 1075
註冊時間: 週一 11 8月, 2003 16:10

文章 HK.Raymond.Tse » 週五 25 6月, 2004 12:14

Dear Chan Sir,

Besides Shiu Hau, will you consider going to East Dam ?

How about your 14-inch dob ? I am considering to order a Johnsonian dual axis EQ platform (Type V can handle up to 140 lb) for astrophotography with and/or without webcam autoguide. Do you wish to give the EQ platform a try for your 14-inch dob ?

Raymond

Chanlunlun
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註冊時間: 週四 09 10月, 2003 21:06

文章 Chanlunlun » 週五 25 6月, 2004 15:28

HK.Raymond.Tse 寫:Dear Chan Sir,

Besides Shiu Hau, will you consider going to East Dam ?

How about your 14-inch dob ? I am considering to order a Johnsonian dual axis EQ platform (Type V can handle up to 140 lb) for astrophotography with and/or without webcam autoguide. Do you wish to give the EQ platform a try for your 14-inch dob ?

Raymond
Dear Raymond,

The telescope is designed for transported to Water Mouth. To go to East Dam we need a car for the round trip. Unfortunately we do not have a car.

If a Johnsonian platform is available I am more than happy to give the 14" a try on astrophotography. However the design of the 14 inch is for visual purpose only which means that the structure may not be strong enough to hold a camera without tube flexture.

Best regards
Chan Yuk Lun

HK.Raymond.Tse
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註冊時間: 週一 11 8月, 2003 16:10

文章 HK.Raymond.Tse » 週五 25 6月, 2004 15:54

Dear Chan Sir,

May try a light-weight DSLR camera such as Canon300D (have to borrow from somebody), plus a light weight guider scope 8x50 (which I already have) for webcam autoguide.

Just 2-5 min exposure, to test the suitability of dob for astrophotography.

Raymond

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Wah!
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文章 Wah! » 週五 25 6月, 2004 21:07

座上去追住d星來睇都好正喎~ :lol: :lol: :lol:
個EQ platform幾時有實物睇呀?

Chanlunlun
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文章: 3828
註冊時間: 週四 09 10月, 2003 21:06

文章 Chanlunlun » 週五 25 6月, 2004 22:13

Wah! 寫:座上去追住d星來睇都好正喎~ :lol: :lol: :lol:
個EQ platform幾時有實物睇呀?
Dear Mr. Wah!,

While we were making the 14 inch last year we tailor made an equatorial platform for it already. I would say that it is very good thing to use an equatorial platform because we don't need to track the objects.

The equatorial platform is now still in good condition. However it cannot be used for astrophotography as it is only a single axis drive design.

Best regards
Chan Yuk Lun

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