Semi-Permanent Observatory -

[paul]

My skills don't quite match my dreams but I've manged to cobble together a semi-permanent observatory. This was very much a half-baked idea fine tuned as I went along. Its rough and ready but it works!

Built in a couple of days at the end of November it has spent most of its time in lock-down due to bad weather. I've been able to image on three evenings for about 8 hrs in total, the observatory has allowed me to maximize that time.

Design goals:

• Very low cost - if it doesn't work out its no major pain.
• Low/no maintenance
• Simple design, easy and fast to construct
• Can be moved if I chose the wrong location.
• Maximize viewing. (I have many obstructions, I didn't want the Obs to reduce the sky further)
• Waterproof and damp free - so I can leave my equipment setup.
• Quick to close up when the session ends

The solution consisted of a  Dancover 2x2x2 Portable Garage (£172), decking material (2x 2.4m composite planks, 2x2.4m wood planks, and 7x 40x70mm frame wood), 2 tough ground sheets,  and a pair of Suitcase wheels, securing straps. I estimate the total cost under at £280.

The idea was to try something out, if it worked then to think about a permanent wooden solution that is more acceptable in a shared garden.

Here it is finished and all lashed down:

 

This view is at its east facing entrance, the velcro door flap is secured by two flower containers filled with gravel that even though they are heavy are easy to swivel out of the way to roll-up the flap. For bad weather protection the whole observatory is secured to the ground using cargo straps that supplement the internal anchorage.

anchored using 4 x spiral stakes (often sold as trampoline anchors)

To open it up I swivel the flower containers out of the way, roll up the flap, slacken the external straps, slacken the internal straps and the then pull the whole garage to the west leaving a base with the equipment all ready to rock. It really does take less than 5 mins. To close it up I stand inside the garage tent part and push it up using the metal cross strut and walk the top back to the east - very quick for when the rain turns up.

I wanted a roll-off roll-on solution but I am not a mechanical/woodwork sort of person so it had to be very simple.... At the end of the garage-top frame I fitted a luggage wheel on each side:

The garage frame...

 

(Rookie mistake, all the horizontal bars should be on the inside of the frame - easily fixed!)

The garage tubular frame is lightweight and easy to assemble (it can be put together by one person with some struggle).  The whole frame can be picked up easily but the verticals just push together - hence the rainbow gaffer tape while we moved it around. Normally the vertical poles push in to the ground but I used 2.4m decking wood as skids, drilling/chiseling holes for the poles then screwing the poles to the wood:

Using the same material I created a cross bar at the rear to the garage frame, this will keep the sides from splaying apart too much as it rolls open and its the handle for lifting up the top when rolling it open.

Using basic decking planks I constructed a frame to keep the garage top off the ground and channels for the wheels to run along. Composite planks were used on the bottom for a water proofed rigid run. The wooden planks were screwed to the composite planks to form the sides, the rectangular inner frame was made with decking posts. (Pro-tip: fit the garage cover to its frame and velcro the door closed, when it all fits together well you know the real width of the garage base and so how far apart the two channels need to be placed - wish I had thought of that at the beginning!).

I drove stakes into the ground and screwed the base to them to improve the anchorage. I then covered the whole of the base with heavy duty waterproof tarp:

I tacked the tarp to the wooden frame using roofing nails. You can also see a cup-hook anchor point that I use to secure the garage to the base with adjustable straps.

When the Obs is locked down the rear bar butts up against the rear of the base making an effective seal:

I set up some equipment inside the obs for a few days just to monitor the environment. I discovered very quickly it was damp inside (I was using some damp paving inside the obs for leveling the mount and to raise equipment off the floor. Any moisture inside the obs condensed  on the inside surface and dripped over equipment. I fitted a second tarpaulin  between the frame and the cover to see if that and the air between them would act an insulating layer (As it had been raining I was also a little concerned about pin-prick holes in the main cover allowing the rain in).

I placed a 400W fan heater inside the obs to drive out the moisture. Leaving that running for a couple of days drove of the excess moisture and the issue did not re-occur.

Fears about rain coming in were unfounded, the velcro door seal is very good, the cover is water tight, none of my fastenings have worked lose, it doesn't move. It has been immune to the very high winds and driving rain of the big storm we had before xmas.

I was concerned that on days when equipment dews up I will be leaving  damp inside the obs that will at the very least mist up any optics. I decided to fit a Sonoff temperature and humidity switch to drive the fan heater. I have it set so that it keeps the temperature a couple of degrees above the forecast ambient. I'm managing this threshold remotely at the moment, I'm hoping to make this automatic.

In late December I got the confidence that my observatory was doing its job properly that and I could commit my more expensive gear to it:

Using the custom Park feature of my new CEM70G I can set the scope at a good angle for the top to clear the OO 250mm.

I am the first to admit this is a little messy, but the concept seems sound.

Cheers,

Paul

[Carastro]

Sounds a great idea for your purposes.  I wonder how it will stand up to wind, although I assume if you know there is a hurricane coming that you will pack it away for the duration.  

It won't keep the wind of the rig like a permanent observatory would but there are plenty of pluses to this idea.

Carole 

[KevS]

Really good and fairly simplistic solution for the perennial obs or not to obs problem; like it. ? 

[paul]

@Carastro ? Big wind is a concern and I probably will move things to the house/shed in a really big storm but I am pretty confident after storm Bella hit us that my obs can take most things. Although its tent-like the whole thing is a rigid structure and doesn't flex when its lashed down. These garages are designed to stay out in all weathers, there is advice on the manufacture's website about avoiding wind under the flaps ?. I think my solutions avoid that and improve on the anchoring they suggest. Never say never though. In the worst situation I might remove the cover and leave the skeleton out in the elements..

I have a remote camera with night vision in the tent, during storm Bella I watched through the night to see what would happen, I didn't sleep much and I could see the inner tarp sway like a curtain in a draft but the structure didn't move and it remained bone dry?. 

[paul]

@KevS And it got my wife's approval as not being too big. She even suggested that a more traditional tidier obs might be considered acceptable in the future ...

[TerryMcK]

I like it. It is certainly better than my jousting tent that only comes out in the summer.

In this recent spell of calmish weather I have been leaving my mount out under 3 waterproof covers, leaving the scope indoors. I bring the scope out if the weather apps concur and take the covers off. At least that way I am still polar aligned and still have to keep an eye out for rain. But I like the garage approach you've done. 

[KevS]

Posted by: @phar

@KevS And it got my wife's approval as not being too big. She even suggested that a more traditional tidier obs might be considered acceptable in the future ...

I have now gained "command approval" for a permanent set up. Start showing the other half photos of summer houses with window boxes.

[MartinS]

Good news KevS, building an observatory was the best decision I took for enabling my AP in the U.K. Having both systems up and imaging within 20 mins provided the ability to respond to often late notice, short windows of opportunity, greatly improving my data collection.

Have you decided on a design for your observatory, ROR, RoS or Dome arrangement? 

[KevS]

Posted by: @MartinS

Good news KevS, building an observatory was the best decision I took for enabling my AP in the U.K. Having both systems up and imaging within 20 mins provided the ability to respond to often late notice, short windows of opportunity, greatly improving my data collection.

Have you decided on a design for your observatory, ROR, RoS or Dome arrangement? 

I am probably going for a permanent pier, replete with a command centre shed. So I can drop the rig on, plug and play as it were. Failing that I have been looking at David Banks's set up (AKA Skipper Billy). Which would do nicely for the obs itself but I would need to board out the rear of the garage (stud wall) for the Warm room. 

Astro-Imaging (davidbanksastro.com)

[MartinS]

Having built the Dome OBS I quickly realised there was not enough room for the 12” meade, me and the imaging equipment, so I utilised a Ketter 6x4 plastic shed that was fitted out as the control room. My wife said it wasn’t big enough and true to her words a year later I replaced it with a ROR observatory with adjoining control room, these things have a habit of growing. The stud wall arrangement sounds good and relatively easy to construct. Good luck with you observatory build, I look forward to seeing some pictures.

[KevS]

Posted by: @MartinS

Having built the Dome OBS I quickly realised there was not enough room for the 12” meade, me and the imaging equipment, so I utilised a Ketter 6x4 plastic shed that was fitted out as the control room. My wife said it wasn’t big enough and true to her words a year later I replaced it with a ROR observatory with adjoining control room, these things have a habit of growing. The stud wall arrangement sounds good and relatively easy to construct. Good luck with you observatory build, I look forward to seeing some pictures.

It won't be until the spring (semi dry season) here in Lincolnshire.

[paul]

Storm Christoph was brushed off, not a single drop on the inside and no weakening or slackening of the anchors ?. Mounting a camera on the inside of the observatory frame made it look and sound quite dramatic though!

But boy, when the freeze happened yesterday materials change their characteristics. The external black straps that are incredible floppy  normally turned in to steel-like hoops. That makes it very easy to remove the straps when they are loose enough but you have to loosen them first. The rolled up part of the strap was frozen to itself which made releasing the ratchet mechanism very tricky. 

Although no running water there is humidity inside....until the cold snap it was 80-95% humid. During last night's clear skies and big freeze the DSLR registered 10 degrees and the Coma Corrector felt sub-zero. There was ice on the secondary vanes. The warm humid air that was between the lenses of the corrector condensed out as steam on the lens, also on the camera side of the LP filter. A hairdryer fixed it a bit but I need to store the camera and corrector away from the scope.

 

The laptop is housed and used in a plastic box, I now plan to put reusable desiccant pouches in the box and put my camera and coma corrector in the box with the lid on at the end of the night. I've ordered a USB fan. As I often leave the laptop powered for a while until morning I figure with the box sealed the temperature will raise a bit, and the fan will  circulate the air and everything should evaporate and dry out below ambient. I might put a humidity sensor in the box to monitor progress via Home Assistant.

 

 

 

 

[paul]

Its in to its second year now and the tent continues to perform well, nothing wrong with its waterproofing or frame. I plan to resite the tent a few meters closer to the house  to get lower easterly shots and wider northerly views. I'll will also run a more permanent power connection to it (double skin flex in a buried duct from the shed).

 

I'm still relying on my WiFi link but have now switched from VNC to Windows remote desktop as I like its built in security and audio (I can here PHD2 "ping" when it loses a star).

 

The only major issue I have  is condensation. I seem to be  solving that by ensuring the scope is parked slight mirror down, dew straps are set to maximum and I leave them powered 24/7 the day (<> 15W). I also have a dew heater on the camera/CC which drives off condensation on the  filter wheel. If everything has been covered in dew/frost I close up the tent and switch a fan heater on for a few hours. That and the natural heating of the tent by the sun seems sufficient to keep it dry.  Occasionally I need to use the trusty old hair-dryer but that has been when I blocked air flow in the OTA.

[Cumbrianwolf]

Just noted this post after the chat on my post and what a great build, thought about something similar but cannot decide on the location in the garden that would be best suited as no one spots suits it all. I could make it into a summer house kind of thing to have dual uses for me and her, the possibilities are endless, but the cash flow is. 😉

[Dave_S]

Any form of cover, is better than no cover at all, and that one works for you,  so well done on your innovative solution. 👍

 

Back during my previous imaging days (2002-2014) I built an observatory with a Roll-off- Roof, but still a cold operation 🥶. So I built a warmroom on the side of it. I later replace the R-o-R with a rotatable octagonal turret.

 

 

When I came back to astro imaging last Autumn (by then we had moved house), the intention was just to use the HEQ5 Pro tripod, setting it up each time, then putting it away after. This idea lasted all of 5 minutes😅.

 

The next move was to install a permanent pier in the garden, leave the mount on the pier, and Polar Aligned.

 

The idea of standing out in the open, bearing in mind the comfort I enjoyed back in the day, didn't appeal ☹️, so I moved the operating position into the summer house, and control everything remotely,  in the warm with a Fan Heater. 

 

I don't leave the scope on the mount, but just clamp it on when I am going to use it. The pier and mount get covered with a good quality weatherproof fitted cover.