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Rooftop observatory challenges

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#1 Ittaku

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Posted 22 January 2021 - 03:53 PM

I'm well aware that people are advised against observing from their rooftops to avoid the heat plumes rising from a home, but since we're considering building a new home, I'd like to know just how bad this will be, and if there are any ways to minimise or completely ablate the problem? I've seen some dome selling websites which show some rooftop installations so clearly some people think it's okay. Does anyone have any experience in this area or recommendations? To be clear, it will be in a light polluted area, and the bulk of what I do is planetary or bright objects so not sure if that alters the requirements.


Edited by Ittaku, 22 January 2021 - 03:55 PM.

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#2 AstroCatinfo

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Posted 22 January 2021 - 04:11 PM

I have an observatory at my home’s roof top terrace. I only do deep space astrophoto working at 1,74”/pixel resolution which is medium range resolution... for planetary the requirements are much higher in terms of local seeing... it all depends which kind of AP you will practice that will define your minimum observatory specs.

 

That’s all I can tell you from my experience. Best wishes and congrats for the new home project.

 

Aleix


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#3 lee14

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Posted 22 January 2021 - 04:12 PM

It's primarily a matter of the magnifications you'll be using. For low power views it won't make much difference, but you will likely see some degradation in the higher powers used for planetary observation. A well insulated attic will help, rigid foam against the interior of the roof deck would be an advantage also. Preventing the interior attic air from escaping around the scope is a good idea as well, and that depends on the design of your system. Despite the potential issues, a roof based observatory is so convenient, and such an elegant solution, I would never discourage you from doing so.

 

Lee


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#4 Ittaku

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Posted 22 January 2021 - 04:28 PM

It's primarily a matter of the magnifications you'll be using. For low power views it won't make much difference, but you will likely see some degradation in the higher powers used for planetary observation.

Okay thanks, but high power is everything with planetary imaging so it seems it's probably not such a great idea.



#5 eyeoftexas

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Posted 22 January 2021 - 04:30 PM

I do not have such an observatory, so this answer may not be useful.  Because you are in the planning stages, you might consider how to have the observatory more towards the end of the house (or on a side).  The reason being, so at least in some directions of viewing you would not be viewing over the roof, but instead away from it.

 

Good luck!


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#6 photoracer18

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Posted 22 January 2021 - 04:39 PM

Realistically the farther it is from your house the better. And don't build it to the north of the house where it has to see thru the heat bloom of the house to see the southern sky. Everything else is a compromise. These days with remote control there is no valid reason to attach it to the hottest thing in the area unless you have no choice. I have serviced a number of home observatories some with domes on the house so I have some experience with this.


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#7 bobzeq25

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Posted 22 January 2021 - 04:43 PM

I'm well aware that people are advised against observing from their rooftops to avoid the heat plumes rising from a home, but since we're considering building a new home, I'd like to know just how bad this will be, and if there are any ways to minimise or completely ablate the problem? I've seen some dome selling websites which show some rooftop installations so clearly some people think it's okay. Does anyone have any experience in this area or recommendations? To be clear, it will be in a light polluted area, and the bulk of what I do is planetary or bright objects so not sure if that alters the requirements.

One thing you can do if you're building a new home is to make _major_ improvements in insulation and air leaks.  Good for a variety of reasons.

 

High efficiency furnaces/airconditioners/hot water heaters vent less heat.

 

If you seal the house tightly, you'll need to pay careful attention to ventilation.  Heat exchangers are a tool, and the system could be designed to exhaust in the proper location.

 

Bottom line.  Energy efficiency will help.


Edited by bobzeq25, 22 January 2021 - 04:45 PM.

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#8 Ittaku

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Posted 22 January 2021 - 04:48 PM

Realistically the farther it is from your house the better. And don't build it to the north of the house where it has to see thru the heat bloom of the house to see the southern sky.

Thanks, though in my case it would be don't build it to the south of the house to see the northern sky?


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#9 vrotondi

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Posted 22 January 2021 - 07:51 PM

What part of the country do you live in. I ask because you have to consider the difference in temperature from the inside of your house to the outside. If you are in a cold climate in the winter, you should not heat the observatory portion of your house. You will want to keep the heat transfer to a minimum to almost non existent. Same in the summer, you should not cool the observatory portion of the house.

 

VR


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#10 Ittaku

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Posted 22 January 2021 - 07:53 PM

What part of the country do you live in. I ask because you have to consider the difference in temperature from the inside of your house to the outside. If you are in a cold climate in the winter, you should not heat the observatory portion of your house. You will want to keep the heat transfer to a minimum to almost non existent. Same in the summer, you should not cool the observatory portion of the house.

Temperature here varies between a minimum of 0 and maximum of 45 ©. The house is almost always between 18 and 26 degrees though. Interesting thought about not cooling or heating that portion of the house - the garage could serve as the base potentially then.


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#11 *skyguy*

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Posted 22 January 2021 - 08:22 PM

I built my garage-top ROR observatory 20 years ago. The attached garage is not heated, so that really cuts down on any problems with heat plumes. Also, the roof on my home has R40 insulation, which certainly helps. I also feel that it's important to place the observatory over a garage or other areas in the home that are not heated since any water leaks will not damage drywall, which would cause some expensive repairs. Personally, I've never been bothered with water leaks in my observatory, but there has been some severe storms with high winds that left a few drops of water on the cars parked inside the garage.

 

The 12" SCT in the observatory is used almost exclusively for imaging. However, it's used occasionally for high magnification, visual observations of the planets and moon. I've never noticed any heat plumes that would interfere with some of the best planetary views I've ever seen ... through any telescope.

 

Good Luck with your observatory build.

 

OrbitJet Observatory:

 

https://www.flickr.c...57644177074161/

 

Home_Observatory.jpg

 

 


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#12 StarmanDan

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Posted 22 January 2021 - 08:39 PM

My club has a 24 foot dome observatory on a second floor with the control room downstairs. The drop ceiling of the control room is double insulated with high R fiberglass insulation and blown expandable foam insulation under the second floor deck. The stairway upstairs and entrance into the obs from outside have a double door "airlock" system to keep heat from the control room and outside from getting upstairs to the scope. We have high cfm fans in the dome which draw air in from the shutter and exhaust out. The control room is climate controlled and we had to recently move the heat exchange unit away from the observatory as the heat plume from it degraded our views in that direction. We have a research grade scope and use it routinely for high precision photometey and astrometry so we took extra care building it to ensure the control room environment doesn't contaminate the dome room upstairs.
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#13 Ittaku

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Posted 23 January 2021 - 12:12 AM

I built my garage-top ROR observatory 20 years ago. The attached garage is not heated, so that really cuts down on any problems with heat plumes. Also, the roof on my home has R40 insulation, which certainly helps. I also feel that it's important to place the observatory over a garage or other areas in the home that are not heated since any water leaks will not damage drywall, which would cause some expensive repairs. Personally, I've never been bothered with water leaks in my observatory, but there has been some severe storms with high winds that left a few drops of water on the cars parked inside the garage.

 

The 12" SCT in the observatory is used almost exclusively for imaging. However, it's used occasionally for high magnification, visual observations of the planets and moon. I've never noticed any heat plumes that would interfere with some of the best planetary views I've ever seen ... through any telescope.

 

Good Luck with your observatory build.

 

OrbitJet Observatory:

 

https://www.flickr.c...57644177074161/

 

attachicon.gifHome_Observatory.jpg

This is fantastic and definitely an approach to consider. Thanks for sharing!
 



#14 vrotondi

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Posted 23 January 2021 - 05:29 PM

Here is one of ours on a home in florida. This was on a garage.

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Edited by vitorotondi, 23 January 2021 - 05:30 PM.

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#15 VinceV

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Posted 27 January 2021 - 03:23 PM

House with dome.jpg Ittaku,

As many others have suggested, using the space above the garage works for me. The added second level contains the Control Room (directly below the observatory) and household storage. The attached image allows for 360 degrees of viewing with the main house directly southwest of the dome. By the time I'm using the telescope in our summer the daytime heat has already dissipated. This wasn't in the planning stages when we had the house built in 1992, but it functions just fine for me. Best of luck with your system.

 


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#16 Paul Hooper

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Posted 28 January 2021 - 03:20 PM

As many others have suggested, using the space above the garage works for me. The added second level contains the Control Room (directly below the observatory) and household storage. The attached image allows for 360 degrees of viewing with the main house directly southwest of the dome. By the time I'm using the telescope in our summer the daytime heat has already dissipated. This wasn't in the planning stages when we had the house built in 1992, but it functions just fine for me. Best of luck with your system.

Vince, that looks great!  What was your solution for the pier, if any?



#17 VinceV

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Posted 29 January 2021 - 08:15 AM

Paul, I have suppression pads under the legs of the tripod. No pier. Imaging is better performed when I stay in the control room (using a portable heater to stay comfortable). You can see more on YouTube, just look under "garage observatory". The video is a few years old and needs to be revised, but the basic information is there to be shared. Best of luck and clear skies. 


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#18 happylimpet

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Posted 29 January 2021 - 08:44 AM

One thing that has changed my prejudices against such things is the astonishing planetary imaging done by Jean-Luc D'Auvergne from a balcony in Paris. Youd think the building would wreck the images but theyre first class. I think being away from ground level disturbances brings advantages.

 

Also bear in mind Chris Go images from his rooftop, albeit in the tropics where heat plume sources are probably less important.


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#19 *skyguy*

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Posted 29 January 2021 - 09:32 AM

One thing that has changed my prejudices against such things is the astonishing planetary imaging done by Jean-Luc D'Auvergne from a balcony in Paris. Youd think the building would wreck the images but theyre first class. I think being away from ground level disturbances brings advantages.

 

Also bear in mind Chris Go images from his rooftop, albeit in the tropics where heat plume sources are probably less important.

I've read that building an observatory even 5' - 6'  feet off the ground will help to remove the scope from the turbulent air found at ground level.

 

I've had a number of occasions over the years when I would be imaging in my garage top observatory and a ground fog would roll-in. It would reach a height of about 10' - 15' feet and completely obscure  everything at ground level. However, from the observatory the sky would remain crystal clear. I would get the distinct visual impression of being in a boat in the middle of the ocean.

 

I've seen the work of both Jean-Luc D'Auvergne and Chris Go and they are indeed world class imagers.


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#20 KLWalsh

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Posted 05 February 2021 - 10:01 AM

I’m planning to build a garage with a ‘rooftop’ observatory. I’ve designed the obs section to be at the end of the garage, away from the cars below and on the South side toward the CEQ and Ecliptic. So for most of the sky, I won’t be observing over much roof. Also, there are trees to the west, so by nighttime much of the roof has been in low-angle sunlight or shade for at least two hours.
I live in a forested area. If I didn’t build high, I’d have very little sky to observe. So, it’s build high or don’t bother at all.
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#21 KLWalsh

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Posted 05 February 2021 - 10:09 AM

I built my garage-top ROR observatory 20 years ago. The attached garage is not heated, so that really cuts down on any problems with heat plumes. Also, the roof on my home has R40 insulation, which certainly helps. I also feel that it's important to place the observatory over a garage or other areas in the home that are not heated since any water leaks will not damage drywall, which would cause some expensive repairs. Personally, I've never been bothered with water leaks in my observatory, but there has been some severe storms with high winds that left a few drops of water on the cars parked inside the garage.


I admire your obs a lot and find it to be a great source of inspiration. Esp for my own plans.
One of the facebook pages I follow covers Astronomy, and I often post a link to your OrbitJet Obs when people ask about tall piers.

#22 *skyguy*

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Posted 06 February 2021 - 08:28 AM

I built my garage-top ROR observatory 20 years ago. The attached garage is not heated, so that really cuts down on any problems with heat plumes. Also, the roof on my home has R40 insulation, which certainly helps. I also feel that it's important to place the observatory over a garage or other areas in the home that are not heated since any water leaks will not damage drywall, which would cause some expensive repairs. Personally, I've never been bothered with water leaks in my observatory, but there has been some severe storms with high winds that left a few drops of water on the cars parked inside the garage.

 

The 12" SCT in the observatory is used almost exclusively for imaging. However, it's used occasionally for high magnification, visual observations of the planets and moon. I've never noticed any heat plumes that would interfere with some of the best planetary views I've ever seen ... through any telescope.

 

Good Luck with your observatory build.

 

OrbitJet Observatory:

 

 

 

I admire your obs a lot and find it to be a great source of inspiration. Esp for my own plans.
One of the facebook pages I follow covers Astronomy, and I often post a link to your OrbitJet Obs when people ask about tall piers.

Thank-you for the nice compliment on my observatory ....

 

If you would like to get into some of the fine details on building a similar roof-top observatory, send me a PM.



#23 Bluephoton

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Posted 07 August 2021 - 11:36 PM

Over the garage is the way to go. Also in my area 24" of roof insulation is a building code requirement so very little heat escapes through the roof.

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#24 nof

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Posted 10 August 2021 - 01:12 AM

For whatever it’s worth, I built my observatory on a porch adjacent to the north side of the house. The porch is on the second level. Views to the south are over the roof (flat, with white insulation material coating the roof). The pier was designed to give a view15 degrees over the southern horizon. Sometimes viewing in that direction is excellent, even low. Later is better than earlier, but that is true in every direction as air/seeing stabilizes. The pier is one story high. The southern horizon is darkest , perhaps in part because the house blocks light from that direction.

#25 nof

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Posted 10 August 2021 - 01:12 AM

For whatever it’s worth, I built my observatory on a porch adjacent to the north side of the house. The porch is on the second level. Views to the south are over the roof (flat, with white insulation material coating the roof). The pier was designed to give a view15 degrees over the southern horizon. Sometimes viewing in that direction is excellent, even low. Later is better than earlier, but that is true in every direction as air/seeing stabilizes. The pier is one story high. The southern horizon is darkest , perhaps in part because the house blocks light from that direction.


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