Pulsar 2.2 Observatory (Start To Finish)

[Benjam]

I would like to share my 2019 Observatory project with you and for anyone thinking of a Pulsar Dome in the future. I went for a circled concrete base, I personally think they look better. 

I started by purchasing three 2.4 lengths of CLS timber for stakes and one 8b4 (2440mm - 1220mm) 6mm plywood sheet for shuttering. I had the plywood ripped down at my local B&Q into six inch wide lengths of 8 foot strips. Sorry for using imperial and metric measurements. Total cost £20. 

Now at home, I measured out where the centre will be and cut, one stake from the CLS and hammered that stake into the ground. Using a full length of CLS I marked the centre (1200mm). Drilled a pilot hole and screwed the full length onto the top of the stake so it would pivot and make a circle. Using a spray can of marking paint, I marked out a circle. You could also use a length of string.  

Dug around the circle, roughly 4 inches down and removed all the grass / soil. I made the circle slightly bigger then needed. 

From the remaining 2 lengths of CLS, I cut a further 12 stakes, roughly 16 inches long. I found it easier to cut a point on one end, this would help hammering the stakes into the ground. Using my pivoting method, I put one stake in the 12 and 6 o’clock positions butting up against either end of the full length of CLS and hammered the stakes into the ground. Repeated the process again for 3 & 9 o’clock and the remaining stakes. Using the 8 foot, 6 inch wide plywood strips, I screwed one onto the centre of a stake, making sure it would finish on the centre of another stake. (You will need to mark and cut the strips) Repeating the process and checking levels with a spirit level, thus making a perfect circle. I think I only used four strips of plywood. Having finished with the remaining full length of CLS I used for pivoting, it came in handy to check my levels. ( See picture below) 

I think my circle was a few millimetres out, but for a first attempt, I was more then happy. I used some spare timber and made a few more stakes,  just for added reinforcement. 

I dugout a 800mm by 800mm square in the centre to support the pier and mounting bolts. However, I didn’t build a anti vibration pad, because I’d be operating my scope from inside a warm room for astro photography. 

I worked out where I wanted my power and USB cables and laid conduit underground. I also added a 15mm wide conduit pipe for  continuous  drainage for a dehumidifier. 

The next day I was ready for concreting, thankfully it stayed overcast while pouring the concrete as the forecast for the remainder of June was hot. Well, UK hot.... 

 

 

The day after pouring, I was outside watering down the concrete four times a day for several days to prevent the concrete from drying out to quickly and cracking. 

A few more days later, shuttering came off and no cat foot prints.... 

I added some paving stones around the outside, more to make cutting the lawn easier. Also four stepping stones from the patio to the observatory door.

The grass took a hammering over the summer, I reseeded the lawn and it’s now looking lush and green again. 

28 days later, I sealed the concrete with a water sealer, in-fact, I gave it 5 coats. More to use the tin up then anything. 

Fast forward to September and my Dome was delivered. The weather turned for the worse, I waited patiently for a week, waiting for a dry couple of days.

Construction was a breeze, I had a friend help me, more with lifting the roof on and tightening up nuts & bolts. It’s just impossible by yourself. Anyway after a few hours we had, what looks like a observatory standing proud in the garden. 

The next morning I went around the outside with Silkaflex, it’s a adhesive / sealant / filler, making sure it was properly sealed from the elements. That done, I tackled the wiring. I had a rough idea in my head, what I was going to do. 

I had some leftover 18mm hardwood plywood from a previous project, so with two batons I used silkaflex to attach the batons on the inside wall. This gave me a sturdy fixing for a plywood board to house, plug sockets, light & fused switch. Directly above the incoming  conduit. 

Two coats of white gloss were added to the plywood before installation. I

My plan was for the power cables to run underground on a ring main circuit in separate conduit away from the USB cables. If you refer back to picture one, the power comes into the centre of the observatory then back down a separate conduit pipe, backup to the bottom of the plywood board. I have two repeater USB cables running from a separate conduit pipe, exiting, also at the bottom of the plywood board. I did run a Ethernet cable, just in case, it’s not required as I can pickup WiFi. The USB cables, run my AVX mount and Camera. They run across the top of the floor towards my pier and are sealed in duct tape. To make things slightly more confusing, I have a 4 gang extension cable, plugged into the bottom socket, running back underground in the same conduit as the power to the bottom of the pier. This runs my, Mount, Dew Heaters and camera. 

 

I took the power from the outside wall socket. Sealed the conduit with black silkaflex. 

The USB cables run up the outside wall of my warm room into a waterproof box and directly to my laptop behind the wall. I haven’t secured the conduit as yet, I’m thinking of using  jubilee clips to hold it more securely to the wall. 

Outside and inside view of USB cables, see below. 

With all that done, I turned my attention to the pier. I wanted to custom build a shelf to fit around the pier to house my eyepieces, dew controller, GPS, hand controller and cable management. 

I used the bottom of the pier as a template and drew around another scrap of 18mm plywood, this would be the outside diameter of the shelf. Using the pier multi adapter plate as another template for the inside diameter. I added my dew heater power thingy to the shelf and also drew around that. 

See pictures below. 

 

Made a few holes for eyepieces, cable management and spray painted matt black 

Then installed into the observatory, using four L brackets to hold in place and wing nuts to secure. 

Added all my equipment to the pier, drilled two holes into the pier column and used cable ties to attach my hand controller, it worked out really well.  

 

Added a desk, also from spare 18mm plywood inside the accessory bay, secured with two batons, silkaflex, nuts, bolts and four L brackets. Finished with two coats of white gloss. 

The dehumidifier is setup to run constantly, I currently have it set to run at 50% RH 

I chose the upgrade on the pulley system for the shutter, it came with one carabiner, I added a second, just to make it easier and to keep the nylon cord out my way when observing. 

Heres a few photos from my desk, inside my warm room. 

 

I still need to install my Celestron focuser 

And finally..... a few more photos from inside and out. 

 

 

 

Thank you for taking time to look. 

 

Ben 

 

 

 

 

Edited October 6, 2019 by Benjam

[JeremyS]

Now THAT is a proper job 🙂

 

[tooth_dr]

This couldnt literally have popped up at a better time!  Currently sitting here planning out my 2.2m dome build.  Excellent!  Thank-you!

[Alan White]

Very neat and tidy indeed.
Being a Visual only observer it is at odds with my way of being under the stars,
but as an Imager, yes fully get the whole setup.
 

[tomato]

 Nice installation, very neat and tidy.👍

[Swoop1]

A very nice set up. I like the pier shelf.

[Benjam]

15 hours ago, tooth_dr said:

This couldnt literally have popped up at a better time!  Currently sitting here planning out my 2.2m dome build.  Excellent!  Thank-you!

Your welcome, any questions then just ask. 

[Benjam]

11 hours ago, Swoop1 said:

A very nice set up. I like the pier shelf.

Thank you. 

Talking to Steve from Pulsar, he informed me, they actually used to make a pier shelf but became tired bumping into it, so they stoped production. 

 

Ben 

[Debo]

That's fantastic 

[JamesF]

A very neat little project :)

James

[Cleetus]

Looks great. Can I just ask what the clearance is between roof and telescope when you have a dew shield fitted?

[Benjam]

On 10/10/2019 at 08:40, Cleetus said:

Looks great. Can I just ask what the clearance is between roof and telescope when you have a dew shield fitted?

Certainly, it’s roughly 54cm, 540mm, 21 1/2 inches from tip of dew hood to ceiling.

 

Thank you, unfortunately the weathers currently being really lousy since I completed the dome, totally different story while working on the dome... 

 

Ben 

[Cleetus]

Thanks. That's a lot of headroom. What size is the telelescope? I only ask because I too have a Pulsar dome but, as it is a much older model, I think the design has changed over the years. I have a 12" Meade but with the flexible dew shield fitted it would sometimes scrape the inside of the dome when slewing. Got around this problem by using a much lower tripod. Seemed easier than the other option of digging a trench!

[Bukko]

On 11/10/2019 at 19:42, Benjam said:

Thank you, unfortunately the weathers currently being really lousy since I completed the dome, totally different story while working on the dome... 

 

Ben 

This is a common problem - as soon as you have finished, all the ideal weather disappears and clouds and rain takes over....

 

[Gina]

I had plenty of wet weather when I built my observatory.  Bought an enormous tarpaulin to cover it - roof and all 4 sides!

[Benjam]

On 15/10/2019 at 06:11, Cleetus said:

Thanks. That's a lot of headroom. What size is the telelescope? I only ask because I too have a Pulsar dome but, as it is a much older model, I think the design has changed over the years. I have a 12" Meade but with the flexible dew shield fitted it would sometimes scrape the inside of the dome when slewing. Got around this problem by using a much lower tripod. Seemed easier than the other option of digging a trench!

It’s a 8 inch, Edge HD, 16 inches in length. Floor to tip of shutter is roughly 2500 mm, I’m 5’11 and feel like I’m inside the Tardis. Though if I did this again, I would probably go with the 2.7 dome, I believe the door opening is slightly higher. I’ve lost count on how many times I’ve scraped my back on the underside of the door opening. 

Have you ever accidentally bumped the tripod legs and lost your polar alignment? 

 

Ben 

[Cleetus]

Agree on the door with the back scraping. Not polar aligned so kicking the tripod legs is not that vital in my case. In any case I am always very careful around the legs. Used to have the Meade tripod but it was too high and the legs spread out so much they almost reached the dome walls. My new tripod is much better in every respect. And wood doesn't rust.

Edited October 18, 2019 by Cleetus

[Benjam]

17 hours ago, Cleetus said:

Agree on the door with the back scraping. Not polar aligned so kicking the tripod legs is not that vital in my case. In any case I am always very careful around the legs. Used to have the Meade tripod but it was too high and the legs spread out so much they almost reached the dome walls. My new tripod is much better in every respect. And wood doesn't rust.

Wow, now that’s a proper telescope! I do like the chair you have, I was worried it wouldn’t fit inside a 2.2 dome but from the picture, it looks like you have plenty of room. 

Whats the dial for, above your glasses? 

Ben 

[Cleetus]

To give it its official title it is a "precision hygrometer". Just a thermostat and dial which tells me how humid it is and when to ventilate. The large dial has three sections - DRY, PERFECT, and HUMID. Bought very cheaply from Mr Amazon. These fibreglass domes get very hot in sunshine in summer and on hot days I open the shutter or door or both. Have the telescope covered with a Telegizmos desert storm cover which keeps most of the heat out.

The tripod and chair are from Berlebach in Germany.

[Benjam]

7 hours ago, Cleetus said:

To give it its official title it is a "precision hygrometer". Just a thermostat and dial which tells me how humid it is and when to ventilate. The large dial has three sections - DRY, PERFECT, and HUMID. Bought very cheaply from Mr Amazon. These fibreglass domes get very hot in sunshine in summer and on hot days I open the shutter or door or both. Have the telescope covered with a Telegizmos desert storm cover which keeps most of the heat out.

The tripod and chair are from Berlebach in Germany.

Haven’t experienced being inside during the summer months. I automatically presumed, the dome being coated white would reflect the heat away. Thanks for the warning. I guess the ventilate system you use, is similar to operating a greenhouse.

The chair you have I’ve seen advertised on Flo, £149. 

 

Ben 

[GCG-Observatory]

This is very inspirational, exactly the type of thing I hope to achieve with my dome that I shall be setting up over the next few weeks/months. How have you found water ingress using the circular pad? Do you still get condensation? I was wondering whether using a dpc membrane under the concrete pad would help prevent any rising damp through concrete, and so help prevent further condensation.

[Benjam]

2 hours ago, GCG-Observatory said:

This is very inspirational, exactly the type of thing I hope to achieve with my dome that I shall be setting up over the next few weeks/months. How have you found water ingress using the circular pad? Do you still get condensation? I was wondering whether using a dpc membrane under the concrete pad would help prevent any rising damp through concrete, and so help prevent further condensation.

Thank you, you won’t be disappointed. I love my dome! 

I’ve had no issues with damp or water ingress, which is very surprising with the weather we’ve all been experiencing. I think the key to my success is good preparation. Yes, a DPM is a very good idea and won’t hurt underneath and will give you further protection. I allowed the concrete to cure for 28 days then I applied a water sealer all over, this creates a  barrier stopping any moisture in its path. The instructions said two coats but I gave it five. https://www.screwfix.com/p/thompsons-water-seal-clear-5ltr/52043

Under my floor tiles I have a DPM for added protection. It came as part of the flooring kit from Pulsar. A little expensive, but saved me the hassle of cutting the tiles to fit. https://www.pulsarastro.com/pulsar-22m-flooring-kit-48-p.asp

For sealing the dome sections together, I used Sika Flex. It’s a adhesive / sealant. I carefully applied a bead in between the joins on the outside of the roof and wall sections. https://www.screwfix.com/p/sika-sikaflex-ebt-all-weather-sealant-white-300ml/87344

On the inside, I haven’t experienced any condensation or damp because I’m running a dehumidifier 24/7 on 60% RH. I definitely would recommend a dehumidifier, though make sure you buy the correct type. I know mine will still run at low temperatures were as the other type, won’t work. I’m not to sure on the correct terminology, but if you search dehumidifiers on here, there’s a good thread which explains everything. https://www.amazon.co.uk/dp/B00474K8SY/ref=cm_sw_r_cp_tai_Cuu3Db2JKJ1FS

Please keep posting you’re progress with updates & pictures as I and many others will be keen to follow you’re build thread.

ATB 

Ben 

 

 

 

 

 

Edited November 26, 2019 by Benjam

[GCG-Observatory]

Thats great info, yes I believe from building a condensation prone type of metal shed a few years ago that all the advice to stop condensation was to ensure that the base remained as dry as possible. I think I will go overkill and DPC underneath, do your sealing as suggested and also fit the dpc under the floor tiles. It really is wet here by the Brecon Beacons, so I want to ensure that the dome remains as dry as possible.

I will definitely start a post about my progress, first things first is to pick up the dome and get it home intact this week.

[Benjam]

20 minutes ago, GCG-Observatory said:

 It really is wet here by the Brecon Beacons, so I want to ensure that the dome remains as dry as possible.

I used to work at the outdoor pursuit centres in Pencelli and Llangorse, spent many happy days cold and wet in the Brecon Hills. One minute blue sky, 10 minutes later, a complete white out and 2 inches of snow on the ground... Loved it! 

Personally, I would leave the build till next spring. I just think you will stand a better chance with warmer and dryer weather. But then I guess you’re itching to get started, I know I would be... 

Edited November 26, 2019 by Benjam

[GCG-Observatory]

Yeah I may have to. I'd like to  think I will perhaps at least get the sight levelled and pier hole dug, and if we get a dry spell that isn't too cold, perhaps get the cement done... though that is probably going to be difficult to find this time of year.  Last thing I want is frost or rain damage to a freshly laid base.

Where about's roughly is your observatory based?