我的远程天文台年度回顾-2012 (上集)
我的远程天文台年度回顾-2012 (上集)
很快我的远程天文台已经用上一年多了。
简单的写了些回顾,希望对有兴趣的朋友有帮助。
如有错漏,希望多多包涵指正。
抱歉文章是用英文写的,因为我输入中文实在太慢了。
最近比较忙,下集要待有时间才可以再续。
简单的写了些回顾,希望对有兴趣的朋友有帮助。
如有错漏,希望多多包涵指正。
抱歉文章是用英文写的,因为我输入中文实在太慢了。
最近比较忙,下集要待有时间才可以再续。
- 附加檔案
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- Remote Observatory Annual Review 2012 - Part I.pdf
- 我的远程天文台年度回顾-2012 (上集)
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X2鄧登凳 寫:Thanks.
Very informative, especially the technical details.
Dear Angus,
By the way, I would like to know that the computer (controlling the telescope and linking to internet) and all the electronics of the telescope, are they always on "turned-on" status?
Or just keep the computer on "stand-by" status and wake up the electronics of the telescope only when an access signal received from user?
Please don't mind my silly question.
Peter
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- 註冊時間: 週一 11 8月, 2003 16:10
Dear Angus,
Good reading of your review. We admire your site's high percentage of clear nights. We can only get 1 to 2 clear nights at most on average per month.
From my limited astrophysic/photographic knowledge, I believe that exposure time is affected by F ratio, whereas larger aperture, in addition to higher resolution (if your site's seeing can support higher resolution) can gather more light and let you image fainter magnitude star at the same exposure duration.
Raymond Tse
Good reading of your review. We admire your site's high percentage of clear nights. We can only get 1 to 2 clear nights at most on average per month.
From my limited astrophysic/photographic knowledge, I believe that exposure time is affected by F ratio, whereas larger aperture, in addition to higher resolution (if your site's seeing can support higher resolution) can gather more light and let you image fainter magnitude star at the same exposure duration.
Raymond Tse
Hi Peter,BossKwan 寫:By the way, I would like to know that the computer (controlling the telescope and linking to internet) and all the electronics of the telescope, are they always on "turned-on" status?
Or just keep the computer on "stand-by" status and wake up the electronics of the telescope only when an access signal received from user?
Please don't mind my silly question.
Peter
Different people do things differently. For my setup, my computer is always on (ie 7/24 throughout the year). So is the weather device. When weather becomes fine at night, ACP will run its startup script to start observation. This script will first power up all the necessary equipment: mount, camera, RoboFocus etc. Then it will start all the necessary applications such as MaxIm, FocusMax etc. Then observation will start. For this to work, the power switch needs to be controllable via scripting.
Similarly, when weather turns poor or at the end of the session, the shutdown script will close applications and power down equipment.
1) Yes, my site is seeing limited. That means using a larger scope will not help to get higher resolution although the captured image is magnified more on the sensor. You only get a larger blurred image.funoooo 寫:Angus 兄,
速拜讀完 Part I,有以下幾點詢問?
1.point 4 Seeing - 因我英文 "水"。你的意思是否如下:
因 seeing 問題,就算幾大支鏡和 幾大 CCD 都未能提高解像度? 對嗎? 如果用以 F/10 鏡 + 16803 是沒有什麼益處;雖然放大了。
可否再解一下?
2. point 9 Autofocus - 根據你內文, ACP focus 時會移去找星, focus 完後再移回目標。這樣會否走位?
謝!
2) Every time the scope is moved, there will be some pointing error introduced since the mechnical system is not perfect. Therefore, every time the scope is moved, ACP will do a pinpoint to find out the current location and make another correction move if needed. So the pointing will be very accurate all the time.
Hi Raymond,HK.Raymond.Tse 寫:From my limited astrophysic/photographic knowledge, I believe that exposure time is affected by F ratio, whereas larger aperture, in addition to higher resolution (if your site's seeing can support higher resolution) can gather more light and let you image fainter magnitude star at the same exposure duration.
Raymond Tse
Yes, for a particular object, the exposure time required to achieve a certain signal level is determined by f ratio only. What I have not explicitely stated is I am trying to compare the situation when we are trying to image under the same image scale - ie same magification. Under such circumstances, and assuming we are using the same CCD camera, it means focal lengths remains the same. Therefore f ratio for the smaller aperture scope will be larger compared to a larger scope. Hence, the smaller scope will need to expose for longer in order to attain the same signal level.
Theorectically, (ignore read noise limitation for the time being) there is no limit to how faint stars a scope can image since we can simply exposure for longer until we capture enough photons to confidently detect the star. Only that a larger scope will require less time compared to a smaller scope.
So both the small scope and the large scope can capture an object to the same signal level. Only that the smaller scope needs to expose for a longer time.
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