Plover Hill Observatory

NEW! Motorising the Observatory. Here

Approximate Latitude 55º N, Longitude 2º W, Altitude 682 ft./208 m.


After I retired in 2002 I started house hunting in the Hexham area of Northumberland for a house with decently dark skies and a favourable outlook. After a number of disappointments, I eventually moved to a very nice bungalow with beautiful views North and South. Southerly view shown here under snow, the Observatory site is just off the right of the picture, the fence runs due East-West.

With the Observatory building on order from Astronomydome, I made a start on the base on 31st. March 2004. The obvious place for the Observatory was within an existing circle of shrubs towards the West of the garden. There were already a number of substantial stone slabs in the ground , well settled after many years - a good foundation for the bulk of the 'walk on' slab.

Once the overgrown turf was cleared away the centre slab was larger than it first seemed, and was VERY heavy! But judicious application of the heel of a large axe in lieu of a sledgehammer soon broke up the 4" thick sandstone lump into manageable pieces. (I later got some flak for that from a friend who would have given her eyeteeth for the slab. With hindsight, perhaps I should have lifted and saved all the slabs. But they did make a very good foundation!) The perimeter of the hole is now approximately 30" x 36" - a good size for the block, I just need to go down a bit!

The 8 ft. Observatory dome comes with precast perimeter blocks and requires an 8' 6" base. So I'm making a 9' base to give support round the edges.

Finally a check on the levels before I start digging! Apart from a bit of a fall away to the South, the area is level within about half an inch. I intend to cast the pier block about 3" above the lip of the stone slabs, with the circular slab to follow at the same level.

After some hard labour...... A gravel incursion in one corner - possibly an old soakaway. So I didn't go any deeper there, but stepped the hole down a bit further at the other (South ) end. The finished block will be about 32" (0.8 m) deep at the stepped end, and will weigh approximately 1200 Kg. I think I'll hire a cement mixer!

Now I was ready to start on the really hard bit! Easter weekend was approaching, and the local builder's merchant had a special offer on - three days equipment hire for the price of one. Too good to miss! So on Easter Saturday I set up the hired mixer and barrow, next to the previously delivered 'dumpy' bags of mixed sand and gravel .

And of course the cement needs to be kept dry. My old Daimler wasn't too impressed! By the end of the job it needed a wash!!

So off we jolly well go! Two large buckets of sand and gravel to one small one of cement was about right. And start the next mix off before pouring the previous one - with only myself working, I had to make the best use of my time!

Into the barrow.

And into the hole. Nearly full now!

Tamp it down.

And smooth it off when full to the brim. The excess of the last mix filled in some of the South side fall away.

Don't forget the pipes to run wiring into the Observatory and through the slab to the pier!

Leave the block to set for a day (Easter Sunday) then start again on the Monday. A new meaning to the term 'level pegging'! I left the blockboard around the centre to help minimise vibration transmitted from the surrounding slab.

Because of restricted access I had to leave part of the outer formwork off to get to the rear of the slab.

But eventually the work progressed far enough for the (almost perfect!) circle to be completed. The ground is well drained and stable, and the slab is over 6" at its thickest, with support from the existing stone slabs at the 3" thinnest parts, so I didn't feel there was any need for reinforcement.

(Fifteen years later there's no sign of movement or cracking.)

Still Tamping!

At last the slab was complete. A brief shower puddled on the surface, but that was soon removed.

And I enjoyed a well earned G & T!

Add the final touches! I'm PHV, CMR was behind the camera, and provided support and sustenance. She couldn't safely step over to the centre, so had to wait until the slab had cured - see later. That's 12th. April of course - English date convention!

Now leave it to cure for a couple of days!! I was very fortunate with the weather. After many days of wind and rain, I had three consecutive days of cool, calm conditions with only a couple of light showers while I was working.

Here as promised - CMR! The pink monstrosity attached to Carolyn's left arm is a 'Short Arm Thumb Cast' She allegedly detached a thumb ligament and sustained a hairline fracture of her right fibula while skiing in March. I reckon it was just a ploy to get out of digging and laying concrete! That was why she couldn't safely step over to the middle block while the pad was still soft.

Actually the injuries were rotten luck - her first skiing holiday and she had a bad fall less than half way through it. But many thanks for the innumerable cups of tea, coffee, and sandwiches which kept me going.

So with the base ready, all I needed was the Dome! And it duly arrived on 24th. April, complete with erection team. First job - install the base ring with quick setting cement.


The dome parts were built in a workshop in sections, completely assembled to check the fit, then disassembled for transport.

And here's the first section on the base.

All the parts fit together beautifully! John (don't be shy!), Graham and John's son Alex. What a team!

The side sections were then pulled tightly together, bottom first, then top as here, and the fixing plates screwed on.

All the larger components had to be carried round the end of the house. The dome halves needed the full team! Note the foam protection around the rim. At all times the attention to detail was absolutely first class.

With the dome halves installed, fit the runners for the sliding aperture.

And fix the whole thing down to the slab.

Finished!! Now that the Dome is up I can determine the height needed for the pier. But for the moment I can observe with the tripod. Once the pier is installed I can fit a raised floor and carpeting - keep my tootsies (feet) warm!

Peace is restored. We were most fortunate in having a fine calm day for the installation. I can't praise the workmanship and standard of construction too highly. Quality with a capital 'Q'. Astronomydome definitely recommended!

Postscript. Unfortunately a few years later they ceased trading. Don't know why, but a pity. The dome is still going strong after 15 years (but see lower down about some woodwork deterioration.)

Still more to do! First job, run mains power (and burglar alarm wire) from the observatory through the shrubbery and beside a path to the nearest access point. Then with a holiday approaching and the pier to be constructed, I just enjoyed observing for a few days. A glitch in the Gemini controller required a replacement unit, but this duly arrived from Hungary and all was well again.

I was away on holiday for a couple of weeks, but meantime the pier was progressing. Some time ago I had been given some 8" diameter stainless steel tube. So with a top plate and base design prepared, the pier was being manufactured while I was away. Ready for installation on my return, and a fine job, courtesy of H. Mullins (also sadly ceased trading in 2016). But it had to be bolted solidly to the block.

Rawlbolts were used with 12 mm thread size, requiring 20 mm holes in the concrete block. Four holes to match the holes in the pier base. Anybody who has drilled holes in concrete will know how tricky it is to get them exactly centred. So I had to be very careful, as the holes in the base were 13 mm dia, only allowing for small discrepancies.

But it fitted first time. Phew!! Then filled with around 150Kg sand and gravel (I had plenty left over from the base construction) to further increase stability and minimise vibrations.

A raised carpeted floor is nice to have. Much more attractive than bare concrete, warmer on the feet and elevates the viewing position slightly. It's much easier to fit a carpet when you can lay the floor on top of it!

The previous night I aligned the pier top plate with true North. So with the plate bolted to the pier, the pier painted, and the floor in place I could finally mount the Gemini, carrying the TMB tube. When the Maksutov tube arrives, I intend to mount both together side by side with a suitable carrying plate.

A gravel path around the dome adds the final touch and improves access for maintenance and shutter operation.

And there it is! 11th. June 2004. A bit over two months from start to finish. I'm undecided about a fitted table, but for the most part the labour is over, and now I can settle down to enjoying the Observatory.


Post Script. 21st. July 2004.

Power points and work space. I finally decided to fit permanent shelves, one of them as a table, curved to match the dome wall.


And finally.... (well some things are never finished.)

Later that Summer I laid a patio at the main garden entrance from the house (via a Conservatory) and a path to the Observatory. So I can get from my house to the Observatory without walking on the grass. And on cold winter nights, if I'm taking a longish set of images it's easy to retreat to the warmth of the house!

The following Summer (2005) I also laid slabs on a small raised area, previously grassed. This makes a nice observing platform for visiting astronomers to set up their own telescopes. (Once they move the bird bath!)

After some years of using my laptop for imaging, as it became a little less reliable and needed extras to run modern USB 2 equipment, I replaced it in March 2010 with a mini computer, utilising a spare monitor. A nice permanent installation (my laptop is still eminently usable for star parties etc.) At night of course I have a red film over the screen (inset).

Around 2011 a bit of rot appeared on the dome above the door. A small amount of patching seemed to do the trick. But it reappeared with a vengeance in 2013, quite extensive and other areas also affected. Weathering of the paint also was greater than usual, so although it had been repainted before, major work was necessary. Strangely in some areas where water was lying under paint there was no deterioration, but this time after removing the damaged wood I gave all bare areas a thorough soaking with preservative before starting repairs. The worst affected sections were reinforced with fibreglass mat before filling and undercoating.

There were a couple of small areas also slightly damaged at the bottom and to the left of the door, but these were easily fixed. Then all affected areas gloss painted. Hopefully the repairs will stand the test of time, but I'll have to keep a closer eye on the paintwork - clearly ingress of water through cracks in the paint was the prime cause of the damage. Presumably flexing of the dome combined with temperature variations is the root cause of the cracking - I might need to repaint every year. Unfortunately as mentioned above the manufacturers are no longer in business, and if a replacement becomes necessary most commercial offerings around this size are lower and smaller. Fingers crossed!

A couple of years previously I replaced the gravel path with concrete - I found that weeds took hold despite the presence of a membrane, and clearing up after trimming the shrubs was a nightmare. Also walking round the observatory late at night was rather noisy!

More Damage :-(

In February 2016 I was showing a friend the Observatory and partly closed the roof to keep out a slight shower. But a gust of wind caught the shutter and forced it off the ball catch which holds it in the half open position. It crashed down on the open side buffers which had evidenced some rot in 2013, particularly the one to the right. They were both dislodged although held the shutter from moving further. The buffer on the right came away completely, exposing serious rot damage. This was the main load bearing spar for the buffer!

The rot had also affected the interior section that the spar was screwed to, so that had to be repaired. And there was extensive damage in the general area. Not so bad for the other buffer, the underlying wood was weak but intact, and I decided to leave it alone - I may need to dig deeper in a year or two! The main spar which was so badly rotted had to be replaced of course, and a further external section also needed replacing along with a substantial area of plywood skinning.





So the rotted sections were cut out and the remaining wood treated with preservative and hardener. The main frame was built up to the original form with fibreglass paste to take a replacement spar. A further block of wood was then screwed to that to accept the buffer (the empty hole was a mistake - when I came to fit the section I realised the hole was too high - oops!)





This photo shows the inner end of the spar where it is screwed to the main frame. The orange coloured stuff is the fibreglass later applied externally.



This shows the finished fibreglassing - a double layer of mat replaced the missing plywood skinning and paste built it up to profile as well as strengthening the fixing on the less damaged side. A small piece of wood also helped to fill a space where old wood was removed.


Then resin filler was used to finish profiling the repair.

Undercoat then gloss to finish off and the buffers refitted. Not the prettiest of jobs - I was working against the clock to make use of a few days of fine weather (full Moon so didn't miss the unuseable Observatory too much!), it was cold so slower setting and drying and some bits got stuck in the paint - I'll tidy that up another time. But back in business. The areas at the bottom and left of the door, mentioned in the previous repairs in 2013, also need attention again, but can wait until warmer dryer weather!

Yet More Damage :-(

In Spring 2017 when I fitted a motor to the dome, more damage became evident. See lower down on the Motorising page.

So that's the rim repaired, but the next step is out with the sander and paint hopefully to sort the cracked areas. And the bottom edge of the door still needs fixing. But I'm determined to keep the Observatory going - although there are suitable replacements available, it would be an awful lot of work and fair chunk of money!

A few weeks later. The door still needs attention, and despite a quick coat of gloss, water was still getting in through cracks. However, some serious work with a disc sander then undercoat and gloss has cured the dome leaks afaik. Certainly after 24 hours of rain in July it was still dry inside. Phew!! In future I'll have to keep a close eye on the condition of the paint and have the sander and paint ready ;-)  

In Spring 2018 I finally got round to repairing the bottom of the door and other areas needing reinforcing with fibreglass. A full repaint followed, and the dome was then in good order with no sign of water ingress. It will undoubtedly require annual attention, but hopefully without any more deterioration.

It never stops! Storms in early 2022 twice pulled the sliding shutter off. Some damage, but I was able to repair it up to a point, and refit it with modified guide brackets hopefully to prevent an occurrence.

OK through the Summer, but when I came to do my annual painting of the dome a bit more rot showed up, fortunately just around the outer bottom rim. Strengthened with wood hardener then filled and sanded to profile. Will do the job for now. But I fear the dome won't last much longer - the shutter and guides are deteriorating badly. Being 8 feet in diameter, there seems to be no suitable replacement in the UK. Maybe a job for a good carpenter, but still of course needing constant repainting.

A 9 foot Pulsar Observatory would just fit on the base slab, but I'm reluctant to replace the whole thing, a lot of work, new floor etc. etc. I think with suitable modifications it will be possible to fit a 7 ft. Pulsar glass fibre dome to the existing base which is in good condition. A little smaller in diameter, but would save time, money and a great deal of hassle!