www.astrocafe.hk

Dear all,

With the input from Angus Lau and the tremendous assistance from Kenneth Yan, we are able to present the real-time weather charts of Remote Telescope Observatory (RTO) at Sai Kung.

The RTO is close to Pak Tam Chung (about 6km NW of Pak Tam Chung).

The real-time weather charts (2 hrs duration each) can be seen at :-
http://www.raymondtse-lawyer.com/astro/ ... atory.html

The speed to download the weather charts may be slow due to bandwidth limitation.

Raymond Tse

Congratulations!

是時候裝個全天魚眼鏡了

viewtopic.php?f=20&t=1389&start=140

The all sky camera by fisheye is stil in progress since I want to add
motorized focusing to the 1.3-3.1mm Fujinon Fisheye focus level (by stepper motor & belt)
plus on-off heater fan coil at the bottom to drive out moisture off the arcylic dome
(caused by the very humid seashore).

The stepper motor, MXL belt and controller have just arrived and tested to work.
Need a metal frame to hang them up adjacent to the fisheye lens.

Raymond

moto-focus?! come on no need for such application in Hong Kong.

yes for me in Tibet, but manual focus once in Winter and Summer respectively already fine.

Whether it is manual adjusting or motorized adjistment is the same action but reaching the
Focus level when the lens is high up in a pole on rooftop at night within the small
Dome enclosure is a painful experience. You need
2 person to do the job, 1 outside at the arcylic dome and
1 person to look at the monitor.
I don't have the luxury of an assistant at site.
Motorized focusing by stepper motor will solve the
problem.
Anyway the controller serve another function
to control another stepper motor to flip open
my 2nd scope cover.
That is the point of remote telescope without physical
human presence.

有個說法很對的，那是科研機構的專家說的，遙控天文台並不等於無人值班天文台。

我的經驗是若你在15度左右調好焦距，香港晚上全年温差大部份就在這水平上下10度多點，以魚眼鏡這類監察為主，非錄取漂亮影像為最終目標的器材，其實是不用特別再調焦的。西藏的變化達40度，是有明顯分別了。

當然若有自動調焦方法，的確會方便些，只要不額外產生問題便可以。我的個人取向是東西越簡單越好，例如我的天文台運作半年暢順，也渡過第一次嚴冬證明沒問題後，之後那次我入藏便把三四成的連線等省去，因為越簡單的東西越可靠。

若有機會到我的西藏天文台看看，你會發現原來硬件都十分簡單直接的，我甚至有想法把主控電腦換成手提電腦。

也有興趣哪天拜訪一下你的天文台。

社長 寫:也有興趣哪天拜訪一下你的天文台。

Be my guest at any time when you are in HK and free. Saturday afternoon would be good timing, since you do not need a car permit to pass through the guarded gate during non-holidays.

I am 3/4 done on the remote observatory.

The TEC140F7 + Atik 314L on EQ6 Pro running on EQMOD was formerly operative but now I still require a new motherboard for EQ6 Pro (already shipped from UK 3 days ago).

Another medium-wide field FD300F2.8 + Atik 490EX on EM11 has just been set up to run with notebook MacBookPro.

12.5Z dob was running on EQ platform for planets but I am considering ME2 for remote go-to instead of push-to EQ Platform.

Now designing the bent-type EQ pier (to pass meridian without flip) to house the the Lunt 152 on EM200. Hutech new Sundog would be considered for better solar tracking.

After all these are running smooth, ACP would be used to run fully robotic mode without human wired control. I would need to seek your advice as to how to config ACP.

Raymond Tse

謝謝邀請，稍後安排一下。

我二手買了一個 Celestron Ultima Equatorial Fork mount 回來，用Byers worm gear，有PEC及autoguider port的，可以一顆9v電池用上不只一晚，本來想過用來出埠承105/650APO拍深空的，取其相對輕便及不用三腳，又就打算放在自家天台上玩太陽，因為不用Meridian flip，現在搬家沒有天台了，又打算是否改用行星月面專用鏡的台架，又或者最後不會實現，賣掉算了...

因為這台架本身可以承C11，LS152應沒問題

Dear all,

SQM (un-calibrated yet as off-set value has not been added) Graph (magnitude per sq arc sec) is also added to the weather charts :-

http://www.raymondtse-lawyer.com/astro/ ... atory.html

Raymond Tse

wooooo.... 最暗20.6等，比我在西藏量到的才亮一等

The SQM is not yet calibrated and thus misleading, since it is just placed inside fibreglass housing point out window at obtuse angle.

It will be calibrated later when it is placed inside an arcylic dome and placed on a pole vertically pointing up the sky. By then the
calibration will be done again. But from past experience, 0.5 mag should be deducted from due to the arcylic dome.

No calibation measurement has been done on the fibreglass housing window, but definitely larger than 0.5 mag.

Raymond Tse

曾拿著SQM各地試，總的來說有個概念。

大致上20等已看到很明顯的銀河，可能是80年代大嶼山九嶺涌的情況，19等也比現時大浪東灣好，我想你那裡可能在18等左右

There is a difference between SQM's magnitude and Near Eye Limiting Magnitude (NELM).
Eg.

SQM Mag ; Near Eye Limiting Magnitude
20.60 ; 5.9
18.81 ; 4.4

For YSO, the best NELM would be around 5.4 - 5.5.

I have done similar measurements of other sites.
Taiwan KwanYang about 6.4 - 6.5
GaomeiGu would be about 6.3 - 6.4.
Yinna Hill about 6.3

Raymond Tse

Raymond TSE 寫:There is a difference between SQM's magnitude and Near Eye Limiting Magnitude (NELM).
Eg.

SQM Mag ; Near Eye Limiting Magnitude
20.60 ; 5.9
18.81 ; 4.4

For YSO, the best NELM would be around 5.4 - 5.5.

I have done similar measurements of other sites.
Taiwan KwanYang about 6.4 - 6.5
GaomeiGu would be about 6.3 - 6.4.
Yinna Hill about 6.3

Raymond Tse

昆陽不會比高美古好吧? 我看那個西南面埔里方向的light dome也很明顯的

總覺得用人眼去量NELM不太可靠，看看黃道光、或大面積的銀河表現力，還客觀一點。陰那山沒上過，也不會上，在這地區，2000海拔上下是很尷尬的，正如我去台灣，寧可幸苦點每晚上武嶺拍，也不會停在清境觀星園，看著霧在自己頭上數十米至腳下數十米之間浮動.....

最近朋友有個計劃，我建議他瞭解一下香港以南的一些島嶼，買一個或租個據點也可以，以安置那台超級大鏡，他最近剛買了艘48呎遊艇，有機會和他去看看。我的經驗，從香港往南跑50公里，比往北跑300公里要好，在那些島上往北向香港望，light dome只有廿度高，以上已看到銀河。

http://www1.astro.hk/events/activities/id/273

The SQM has been calibrated last night by setting an offset of 0.925
due to placement inside fibreglass housing instead of
Zenith pointing.
The better reading was 20.05 mag P arc sec, or
about 5.5 Near eye limiting mag.

有機會我帶自己的SQM到你那裡試試，我猜很大機會量到是18-19等。

No-IP routing is now used to prevent frequent changes of IP address.

SQM meter graph will be updated soon after the computer's CPU heat sink is replaced to prevent overheating of CPU; while conversion table of sky brightness magnitude to near eye limiting magnitude is added for easy reference.

http://www.raymondtse-lawyer.com/astro/ ... atory.html

Raymond TSE 寫:No-IP routing is now used to prevent frequent changes of IP address.

我建西藏天文台時很担心這問題，香港用fixed IP，但西藏要用光纖才有fixed IP，每月要2000人民幣，到現在才發現完全不需要，我用手機Apps也可下指令遙控西藏拍星、開燈、關天窗、reboot

Raymond TSE 寫:SQM meter graph will be updated soon after the computer's CPU heat sink is replaced to prevent overheating of CPU; while conversion table of sky brightness magnitude to near eye limiting magnitude is added for easy reference.

http://www.raymondtse-lawyer.com/astro/ ... atory.html

我在這方面又是另一過份緊張的例子，當時用上工控機，但仍遇上不穏定問題，甚至裝好試拍當晚已遇上高山症（在西藏常見的硬盤問題），一回到拉薩準備維修便自動沒事。後來改用一部隨街可以買到的Lenovo枱機，至今連續開機一年，靜得多也穏定得多。

唯一是那裡電力不穏，若UPS加一大一點可以維持半小時則可避免95%問題，但仍有機會停上較長時間停電。

若你有機會看到我現時天文台實況，會很驚奇原來一切是這麼簡單的，只是當年我把事想得太複雜了。

Each observatory will have its own advantages and problems.

I don't know the temperature of Tibet in summer. But if there is a drop of 6C for every 1K meter, then Tibert will be 30C cooler than sea level.

My observatory during June is about 38-45C during bright sunshine. Thus the CPU in my 5 yrs old computer will likely be overheat during the day.

Less of a problem for broadband and electricity stability in HK, however.

One setup is also simplier. I have at least 2-3 setup of telescopes, parking/go-to mounts, computers, electronic finders, guiders etc designed to work at the same time
when the sky is clear. Thus problems will multiply 2-3 times.

Raymond TSE 寫:Each observatory will have its own advantages and problems.

x2

Raymond TSE 寫:I don't know the temperature of Tibet in summer. But if there is a drop of 6C for every 1K meter, then Tibert will be 30C cooler than sea level.

西藏夏天白天最熱可在30度，晚上在10度。冬天最冷時白天在0度，晚上零下20度，但大部份時間是白天10多度，晚上零下10度，某程度上我那裡是西藏各區中氣候比較温和的，而濕度不時在10-30%之間波動，加上海拔4300米，對天文來說是夠高夠冷但又不太過份，因為很多正常儀器及機件到了零下40度以下便會出問題。

我的 FLI Proline 16803是全年統一在零下30度工作的，好處是不用拍不同的暗場，夏天最熱的晚上會用90%以上的功率冷郤，冬天則少得多。

Raymond TSE 寫:EMy observatory during June is about 38-45C during bright sunshine. Thus the CPU in my 5 yrs old computer will likely be overheat during the day.

用Sirius Observatories，因為有太陽能抽氣扇及玻璃纖維本身特性，我試過在盛夏時份用紅外線測温過，台內的温度跟戶外陰影下相差僅一度，即33、34度水平。我常用的Thinkpad或枱機都不會有問題，顏寶鈴書院他們也沒有問題，所以可以考慮如何把天文台的隔熱做些功夫：

viewtopic.php?f=12&t=86

Raymond TSE 寫:ELess of a problem for broadband and electricity stability in HK, however.

現時西藏的互聯網問題不大，每月98元人民幣月費，還包一張無限接聽電話卡。電力在正常情況下無問題，UPS可以應付，但每一兩個月有一次維時十多分鐘的停電，那是人為因素，一年裡有三數次會超過一兩小時，亦有機會會停超過一天，那情況只要停止觀測了。幸好大多數停電是在白天發生，就算在晚上，天文台的保護機制會在斷電後會自動以後備電源關上天文台天窗，安全上沒大問題。