Home Observatories

[Scorpion Rob]

Greetings to one and all,

I have been watching videos of people making home observatories. Some built professionally but a lot homemade from scrapes of wood and bits and pieces. To be truthful, they all look great. My question is :-

How to the telescopes last out in the weather conditions, of freezing cold, condensation, high temps with the son. Some have computers and stuff in there to. No one ever says that they had a short circuit or any issues?

Some I have seen have been direct to the garden floor or grass. I get the you can build a box with a lid but how do you keep the equipment safe and long lasting. I am sure its me missing something but I am curious as if it is a simple answer then I may construct myself. Thank you for any comments or input.

Rob

[Louis D]

I think good ventilation is key to avoid massive heat buildup in the summer (at least in Texas and the desert SW of the USA) and dampness buildup in humidity prone areas.

[NGC 1502]

Hi Rob. I’ve never had an observatory, however - with regard to electronics surviving extreme temperatures, all cars these days are stuffed with electronic gadgets of many types. Cars are out in all the temperature extremes, exceptionally high inside when in a hot sun, and sub zero in the depths of winter.....

I think that all outdoor structures need isolating from damp ground with at least something to stop the moisture soaking in.

Louis D mentioned ventilation, a good point.

Ed.

 

[Louis D]

7 hours ago, NGC 1502 said:

Hi Rob. I’ve never had an observatory, however - with regard to electronics surviving extreme temperatures, all cars these days are stuffed with electronic gadgets of many types. Cars are out in all the temperature extremes, exceptionally high inside when in a hot sun, and sub zero in the depths of winter.....

Automotive electronics have an operating temperature from −40 °C to 125 °C which is very close to mil spec of −55 °C to 125 °C.  Consumer electronics have an operating temperature from 0 °C to 70 °C.

Unless otherwise stated by the manufacturer, we have to assume astronomy electronics to be consumer spec rather than automotive spec and treat them accordingly.  This not to say they could not be stored at extremes beyond these operating conditions.  I know that operating electronics under extreme heat conditions that are not designed for it can lead to permanent failure, typically due to electromigration.  Before this happens though, the device typically starts to malfunction.

[Waldemar]

Applications are available to prevent malfunction by high humidity. One solution I use my self for years already with succes is NanoTech Electric spray
Besides that dehumidification, ventilation and temperature control are all means to prevent problems.
The point is, to stay above the dew point temperature, even with a few degrees will prevent condensation.

Edited May 22, 2020 by Waldemar

[Miguel1983]

Hi,

my obs is insulated kept at 16°C during winter and i have a dehumidifier keeping the RH at 55% give or take, so no issues at all

[mikeDnight]

Hi Rob,

  Being purely a visual observer, I don't have much in the way of electronics other than an RA/Dec drive on my equatorial mount, along with a few lights and an electric heater. When my wife gave me the go-ahead for an observatory in 2011, it was a question of a fiberglass dome or a run-off roof design. I'd seen others have issues with fiberglass domes and condensation, so I thought I'd build my own run-off roof observatory which would be condensation free as far as possible.

  The building was constructed from 3/4" ply screwed to a 3" by 2" frame, which I clad on the outside with double skinned white plastic cladding. This is brilliant for reflecting the Suns heat, and even on a hot day, the inside of the observatory remains at a comfortable temperature and never hot. There is a narrow air gap between the top of the walls and the roll off roof which is surrounded by a rubber skirt, but it still allows air flow and helps prevent condensation.

  The inside of the observatory is clad with black interlocking matting not only on the floor but on the walls also. This was done initially as a way of keeping my observing area as dark as possible and is very effective, but it also has the added advantage of acting as insulation, preventing condensation from ever forming. 

  As regards the equipment, I never leave my refractor in the observatory when not in use, but the 10" reflector is quite happy and I've never had any issues with moisture affecting it or the mount. In fact, my observatory is so moisture free that I'm able to leave star atlases and charts in there without issue and have done for the last 9 years. The 240v electrics are protected with a circuit breaker but I've never had any issue with it. The only draw back is that batteries can drain in the cold winter months. The electric heater serves to warm the observatory when the roof is closed in winter, creating a nice little boys club for me and my observing buddies. I've never needed to use a dehumidifier!

Below is an external view of the white clad 8' by 7' structure, and internal views showing the black rubber clad walls, along with wall charts etc. Even the steel pier is rubber clad to keep all surfaces warm to the touch and to keep cold surfaces where moisture may form to a minimum.

 

[JeremyS]

Hello @Scorpion RobMy dome has been is use for 26 years. No problems at all. The only condensation I've had is after I have been sitting in it for a few hours and breath condenses on the surface. But it soon goes. My drive electronics and permanently out there. I have a dew heater on all the time around the C11 corrector plate and on the drive control pad. I take my CCD + laptop in after each session, but I've also got a couple of laptops in there permanently that are connected to my meteor cameras and they have been operating about 6 years.

Definitely look after equipment, but we have this kit so it can be used and enjoyed, rather than tucked up (I only been known occasionally to take take Tak to bed). Having an obsy is the single most important thing that has affected my observing. To say it was transformational would be an understatement. For anyone that can, I'd say build an obsy, or get a permanent pier and store like @Alan White has just shown us how to do in an exemplary way.

[DHEB]

8 minutes ago, JeremyS said:

Hello @Scorpion RobMy dome has been is use for 26 years. No problems at all. The only condensation I've had is after I have been sitting in it for a few hours and breath condenses on the surface. But it soon goes. My drive electronics and permanently out there. I have a dew heater on all the time around the C11 corrector plate and on the drive control pad. I take my CCD + laptop in after each session, but I've also got a couple of laptops in there permanently that are connected to my meteor cameras and they have been operating about 6 years.

Definitely look after equipment, but we have this kit so it can be used and enjoyed, rather than tucked up (I only been known occasionally to take take Tak to bed). Having an obsy is the single most important thing that has affected my observing. To say it was transformational would be an understatement. For anyone that can, I'd say build an obsy, or get a permanent pier and store like @Alan White has just shown us how to do in an exemplary way.

Looks very nice and elegant with that color. But just curious: doesn't it get too hot inside on a sunny summer day?

[JeremyS]

1 minute ago, DHEB said:

But just curious: doesn't it get too hot inside on a sunny summer day?

Too hot for what? I observe at night 🙂

Open the dome late afternoon and the heat soon dissipates.

Electronics? As somebody else pointed out, electronics are really quite robust these days and our UK climate is moderate compared to many places.

[Merlin66]

Louis,

unfortunately astro equipment is not made to automotive standards....

Not all Astro electronics is as good or robust as we would hope/ expect.

 

[Carbon Brush]

A couple of additional comments on the electronics if I may.

I don't think you can reasonably compare automotive electronics to scope electronics.
At least not in the cost conscious goto mounts. Those that cost a few hundred pounds.

If you want some idea of how tight the build budget is on mass market mount products, just ask why so many do not have a real time clock with battery backup.
The component cost of this facility is about £1 or a little more. But instead you have the faff of setting the clock every time you go out.
Unless you pay extra  money for wifi/gps boxes to obtain the time!

There is a similar argument applicable to the awful DC power plugs on most mounts. Why do so many people replace them?
Take a look around your car power connectors in the engine bay and behind light fittings. Perhaps ugly, but definitely reliable.

RJ45/RJ11 (network/phone) connectors used on the mount curly cables are really intended for indoor applications.
You don't see these connectors in headlamp tilt circuits.

Automotive components work over a wider temperature range than commercial grade.
However, of equal importance is reliability or lifetime.
For example. Commercial grade components cannot be repeatedly temperature cycled without risk of failures.

The next consideration is the PCB material and construction methods.
If the base material is a paxolin tytpe, as seen in toys, this absorbs moisture and changes size with temperature and moisture absorption.
The size changes impose stress on soldered joints, leading to failure. Not a problem with a toy car for Christmas that will be used indoors and thrown to landfill in a few months.
If the manufacturer uses fibreglass, this is more temperature stable and does not absorb moisture.

Next is the damp proofing. Any electronics intended for use where there is risk of condensation is laquer coated.
The type of laquer being determined by the budget.
Some areas cannot be coated. Connector pins and push buttons on to a PCB for example.

If you want your scope electronics to last for years, have a look inside the boxes and think about connectors.
If you have the skills, consider what changes you can make to improve lifetime.

Anyway. Enough said. I'm off now to look at a new Skywatcher scope package.
My blue tube scopes stopped working when black diamond paint came out, so I upgraded.
Now my black dovetails no longer fit correctly. Must get something in green.

I'm not Skywatcher bashing here. Just change colours/model names etc. and insert Meade, Celestron, etc.

Yes all of the mass market scope manufacturers, one way or another, really want us to buy the new shinier product every year or two.

HTH, David.

 

[discardedastro]

I'll throw my hat in - ESTI have standards for temperature/humidity profiles for outdoor, indoor, and locations like street cabinets and whatnot. Most consumer kit will be fine in sheltered locations but once you start looking at sites with heat-trap you tend to go into industrial rated components. This normally gets you from 0-45c to -5 to 70c or thereabouts. In an observatory in the UK you'd be really working hard to get above 40c ambient even with pretty minimal ventilation, so for most kit you'll be absolutely fine.

Humidity is much more of a concern - as David above says you'll normally use fibreglass conformal coated PCBs in electronics if you expect something to get wet, but this is expensive and complex so rarely happens (industrial/mil-spec kit, telecoms etc, yeah - but not your average computer or even most industrial PCs). And there is of course potential for direct impact on scope optics in a more drastic way than heat (hot glass is just hot glass and it isn't like any coatings mind anything but extreme temperatures - so long as everything can expand enough together it's going to be fine).

So as long as you have some ventilation, maybe some insulation against the sun (painting it white is the easiest way to reduce insolation, of course, and highly effective), and a means of humidity control, your kit should last as long as it would stored in a home. My current air management plan is a thermostat-operated fan pulling air in through a box filter (exhausting through a more permissively filtered louvre if it needs it, otherwise just trying to achieve slight positive pressure to reduce dust ingress) plus a hydrostat-operated dehumidifier. That's all it'd take to keep things under 30c ambient and 50% RH 99% of the time.

[Knight of Clear Skies]

It's surprising what you can sometimes get away with. We have an outside switch we use as a wifi extender, it's inside a wooden box and has some plastic over it. It still works after several years but I wouldn't recommend doing this with anything you value.

[mikeDnight]

1 hour ago, JeremyS said:

Too hot for what? I observe at night 🙂

Open the dome late afternoon and the heat soon dissipates.

This reminds me of Leslie Peltier's observatory in his auto biography, Starlight Nights. He too used to open his dome early to let the heat of the day escape. His sister wrote a poem about him, which from memory went like this:  

  Our hero felt the winds first dash, He saw the distant lightening flash.  "My dear" he said "I shall return, some other night with lips that burn.  Right now I have to dash for home, for I've forgot to close the dome."  

  

[skybadger]

I have had two domes now at three locations and stored and operated a computer in each of them., with mains and associated usb/serial cabling

As long as the pc stays warm - for me that meant always on - it was fine. If it failed to start after a power cut then it got damp and the harddrive didn;t ike to play ball unles it came inside for a holiday and dry out. 

The mains has never been a problem, rusting usb connectors have. While i also understand the issues about 5.5 power jacks and lack of industrial latched connectors, once fitted, they don;t move in practice and i don't have a vibration problem so I haven;t seen the need. XLR connectors have been a solution for some. Not cheap. 

In fact, the biggest issue I have had is the humidity over long periods causes or promotes mould on glassware stored outdoors for long periods, so every few years I have to clean down the surfaces of lenses which can be a bit daunting.. Other than that, until now I haven;t seen the need for humidity control and have seen good reports of solar powered vents to provide venting, but now I have a humidity sensor in the dome and can clearly see that it reaches 80% during the night and down to 20% during the day when it warms up, with clear impacts from opening the dome or the doors. That might drive me to be a bit more active in getting some venting fitted. The sensor data below is from an automotive standard HTU21D  temp/humidity sensor suspended in free air inside the top of the dome. 

Edited May 22, 2020 by skybadger
spellings!

[Scorpion Rob]

Thanks Guy`s interesting points from all concerned. I would love to get one but money is a little tight to spend thousands on one. Think the misses would bury me under it.

Mike & Jeremy - Your obsy`s look great. Very impressive

Lets see some others... get ideas going, budget or expensive 🐵

[newbostonian]

I was just reading the comments on this topic and wonder if people with garden observatories have used any of the specialist all-weather telescope covers over the equipment inside the observatories in order to leave them there all year around? The covers would help with dust and extremely low temperatures, but might just add to overheating problems in Summer? 

[Merlin66]

With the TSO my C11/NEQ6 was covered by a dust sheet and in winter after an observing session I draped a 12v heated doggie blanket over to reduce dewing.

It’s done well for almost ten years.

[Ole Larsen]

I build mine Obs. from the bottom, and never finding any kind of condensation. in the north part of Denmark. 

http://www.mit-observatorie.dk   Its in danish, think google can translate