Jupiter through the 20" scope
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- Dave Lillis
- Posts: 2757
- Joined: Sun Aug 05, 2007 10:02 am
- Location: Limerick city
Jupiter through the 20" scope
Hi all,
I recently installed a new fan and thermometers on my 20" scopes primary mirror, to get it cooled faster. I managed to get it down to 1.4 Celsius above ambient (I didn't want to push it any further down incase it dewed over), so I tried out some imaging of Jupiter to see what I could get.
So this is 700 images stacked out of a sequence of 3500. click image to see proper size
http://farm9.staticflickr.com/8215/8294 ... 3a45_b.jpg
I reduced the image scale abit to take out some of the graininess and added a bigger black surround.
The seeing was average, with moment go good steadiness, so I was able to use a 7mm (357x) and 5mm (500x) eyepieces at times. At 500, the moons were clearly tiny disks and had some colour. The eyepiece view was pretty much as you see it here, except not as colorful.
The higher altitude of Jupiter as seen from here compared to previous years has made a big differance. !!
I recently installed a new fan and thermometers on my 20" scopes primary mirror, to get it cooled faster. I managed to get it down to 1.4 Celsius above ambient (I didn't want to push it any further down incase it dewed over), so I tried out some imaging of Jupiter to see what I could get.
So this is 700 images stacked out of a sequence of 3500. click image to see proper size
http://farm9.staticflickr.com/8215/8294 ... 3a45_b.jpg
I reduced the image scale abit to take out some of the graininess and added a bigger black surround.
The seeing was average, with moment go good steadiness, so I was able to use a 7mm (357x) and 5mm (500x) eyepieces at times. At 500, the moons were clearly tiny disks and had some colour. The eyepiece view was pretty much as you see it here, except not as colorful.
The higher altitude of Jupiter as seen from here compared to previous years has made a big differance. !!
Last edited by Dave Lillis on Fri Dec 21, 2012 4:57 pm, edited 1 time in total.
Dave L. on facebook, See my images in flickr
Carrying around my 20" obsession is going to kill me, but what a way to go.
Carrying around my 20" obsession is going to kill me, but what a way to go.
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- Dave Lillis
- Posts: 2757
- Joined: Sun Aug 05, 2007 10:02 am
- Location: Limerick city
thanks guys, I was surprised at how it came out tbh,
I took some images of Jupiter last year at the burren, same setup and was getting some really bad onion ringing on the disk edge, figured out that there was a setting in the capture program to enhance detail which was causing it, that's off permanently now.
The seeing was average, but it was the cooling of the primary that made a huge difference compared to earlier on in the evening...
I have the cooler fan held in a suspension type system so it now causes zero vibration when on, you wouldn't know it is on when looking through the eyepiece.
I'm pondering putting together a proper fully automatic cooling/heating system on the primary, one which monitors ambient and keeps the mirror from getting too cold or warm, its not technically difficult, cooling a mirror is easy, heating it without distortion is a different story.
I took some images of Jupiter last year at the burren, same setup and was getting some really bad onion ringing on the disk edge, figured out that there was a setting in the capture program to enhance detail which was causing it, that's off permanently now.
The seeing was average, but it was the cooling of the primary that made a huge difference compared to earlier on in the evening...
I have the cooler fan held in a suspension type system so it now causes zero vibration when on, you wouldn't know it is on when looking through the eyepiece.
I'm pondering putting together a proper fully automatic cooling/heating system on the primary, one which monitors ambient and keeps the mirror from getting too cold or warm, its not technically difficult, cooling a mirror is easy, heating it without distortion is a different story.
Dave L. on facebook, See my images in flickr
Carrying around my 20" obsession is going to kill me, but what a way to go.
Carrying around my 20" obsession is going to kill me, but what a way to go.
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- Posts: 2980
- Joined: Sun Aug 05, 2007 2:45 am
- Location: Ballycasey, Co. Clare
Sounds cool if you pardon the pun.
The new fan setup sounds like it's working great.
The heating as you say is a different matter.
I assume it needs to be uniform across the disk of the mirror.
That's gonna be tough.
There are a few ideas I have though.
What exactly would be required in terms of heating?
The new fan setup sounds like it's working great.
The heating as you say is a different matter.
I assume it needs to be uniform across the disk of the mirror.
That's gonna be tough.
There are a few ideas I have though.
What exactly would be required in terms of heating?
- Dave Lillis
- Posts: 2757
- Joined: Sun Aug 05, 2007 10:02 am
- Location: Limerick city
oops, meant to reply earlier, the heating would be by 2x 6 or 8 inch heater pads from scopestuff, anything bigger and they would block the fans cooling action, I have a simple circuit that will monitor the primary mirrors temperature and ambient air temperature and will turn on the heat if the mirror falls within 1 degree of ambient (off at 2 degrees) and turn on the fans if the mirror is above 2 degrees of ambient,
The 1 and 2 degree values are completely configurable.
The entire point is to keep the mirror between 1 and 2 degrees above ambient. This should prevent dew-ing while eliminate thermals.
What I'm debating in my head is the effort required to put this together worth it, maybe a job for early next year.
The 1 and 2 degree values are completely configurable.
The entire point is to keep the mirror between 1 and 2 degrees above ambient. This should prevent dew-ing while eliminate thermals.
What I'm debating in my head is the effort required to put this together worth it, maybe a job for early next year.
Dave L. on facebook, See my images in flickr
Carrying around my 20" obsession is going to kill me, but what a way to go.
Carrying around my 20" obsession is going to kill me, but what a way to go.
- Dave Lillis
- Posts: 2757
- Joined: Sun Aug 05, 2007 10:02 am
- Location: Limerick city
got around to processing a second avi from that night, this one is at 22.57, that 39 minutes before the image in the first post.
its abit more colorful, to me it looks a little better, but not as sharp as I want yet though. I think its time to research a better camera,
Its interesting to see how much the planet rotates in 39 minutes !!
its abit more colorful, to me it looks a little better, but not as sharp as I want yet though. I think its time to research a better camera,
Its interesting to see how much the planet rotates in 39 minutes !!
Dave L. on facebook, See my images in flickr
Carrying around my 20" obsession is going to kill me, but what a way to go.
Carrying around my 20" obsession is going to kill me, but what a way to go.
-
- Posts: 2980
- Joined: Sun Aug 05, 2007 2:45 am
- Location: Ballycasey, Co. Clare
- Dave Lillis
- Posts: 2757
- Joined: Sun Aug 05, 2007 10:02 am
- Location: Limerick city
yea, totally agree, a dmk camera would be a killer combination with this scope on a good night,
I do remember the committee had discussed a camera 2-3 years ago, the committee has changed alot since then, don't think it would be on the cards now and funds aren't there for it anyway,,,
Never heard of a second hand one on any market, I think if someone gets one of these, they tend to hang onto it.,
I do remember the committee had discussed a camera 2-3 years ago, the committee has changed alot since then, don't think it would be on the cards now and funds aren't there for it anyway,,,
Never heard of a second hand one on any market, I think if someone gets one of these, they tend to hang onto it.,
Dave L. on facebook, See my images in flickr
Carrying around my 20" obsession is going to kill me, but what a way to go.
Carrying around my 20" obsession is going to kill me, but what a way to go.