11.08.2024 Back to hutch one: Calfotel XL-2?

 ~*~

  Sunday 11th. Warm, sunny and breezy but with rather a lot of cloud.

 During the night I worked out how to provide inverted, raised rails. For two calf hutches to roll apart. I clearly saw two calf hutches separating in my dreams. To provide the observation slit for the twin enclosures. 

 Then I woke up. To realise that these enclosures are poorly designed. To join each other, face to face. Which is only fair. They weren't thinking about idiots like me. Dreaming about making ridiculous observatories out of them. 

 So then I had to start worrying about interfacing them for full weather protection. Only to realise that the two would be over four meters long when conjoined. Longer still when separated. The greenhouse would never see the sun! 

 Which was a bit of a shame. Because I was already laminating Baltic birch plywood reinforcement at their intersection in my daydreams. 😳 

 So I must make do with one hutch and do it sensibly. Just for a change. Size matters, but they all taper inwards at the top. The same headroom but less likely to blow over. Greater stability. Not to mention reduced material consumption. It also makes for an attractive appearance.

 The CalfOTel XL-2 is interesting. L= 226cm x Width 166cm x Height 155cm. Larger and designed to house two calves side by side. It provides enough enclosed space to be able to enjoy greater wind protection. Provided it can face south. 

 Rolling it off to the west would immediately expose the telescope to the prevailing wind. Though the hutch might offer some protection by its sheer bulk. It would make the housing of the telescope easier. Though now at £1000 equivalent. 

 Morning imaging with the sun to the east. Would mean the hutch need not be rolled back so far. Offering a useful advantage. Which is lost when imaging to the south or west. When one of the narrower hutches would do just as well. 

 Rolling the larger XL-2 hutch off to the north might cramp the nearby drive. Or it would soon run into the greenhouse! I have just 4m to play with. Depending how harsh I am with the hedge clippers on the beech hedge.

 I am imagining twin doors covering the open front. Now facing south. Though the design of the existing hood is a problem. It severely limits the altitude to which a housed telescope could point. Summer around mid day means 55º. 

 Which would mean taking a jigsaw to the front of the hutch and then reinforcing the enlarged opening with laminated plywood. To which the doors [shutters] would then be hinged. Doable? Needs further thought.

 XL-2 raised on rails? Make the headroom of the hood [say] 2m. Roll off the enclosure back by 1m? It would mean a scale drawing to be sure but summer mid day is the worst case scenario. The rest of the time the telescope would have enough shoulder and headroom. 

 The downside is the telescope is now invisible if I want to sit in the greenhouse. I would have to have a security camera and screen to check for collisions and cable tangling. Or, I could sit in the back of the enclosure. With the imaging monitor mounted on the pier. As I have been doing for several years in the 3m dome. I'd move my chair to the east or west side. Depending on the angle the telescope is pointing. 

 Whoops! Doing a Meridian flip could be an absolute disaster! Unless I provide enough headroom! The telescope usually goes vertical during the flip. A flip could be carried out manually. Without the telescope trying to lift the entire observatory off its rails! Now imagine it does an automatic flip while unattended. Setting limits on a mounting may cause further problems. Can I allow enough clearance for the telescope to go vertical? By rolling back the enclosure enough? The mounting must be clear of any overhang. 

 The obvious solution is not to have meridian flips. A fork mount and a bent [astrograph] pillar both avoid the problem. Turning something like a CEM120 into a fork is rather pointless. The declination axis isn't designed to be somewhere else entirely. Can the CEM120 be fooled into working with a bent pillar or pier? That's not an everyday question for Google. 

 I used Perplexity AI to discover that the XL-2 weighs 135kg. Or 287lbs. No lightweight then. Yet a YT video shows it being moved, tipped and lowered manually by an elderly gentleman. ChatGPT suggests the XL-2 weighs only 69kg. That better matches the effort the YT "actor" was putting into it. 

 I emailed the CalfOTel company. Only to find my contact on leave until the end of the month! I'll try asking one of their dealers.

 

  ~*~

8.08.2024 And then it was folded.

 ~*~

 

 Thursday 8th. I am expecting a parcel with the Bresser 2" star diagonal today. Now I can start playing with optically folding the 150mm/ 6" f/10 H-alpha refractor. I hope I have enough 2" extensions to lift the filter stack clear of the main tube. I need some of my modest stock for spacing the stack components correctly. Each star diagonal has its own minimum light path distance. Due to the physical dimensions of the body which supports the 45º mirror. This is unavoidable.

 Some of the Lunt stack Modules are very bulky. The pressure tuned etalon is the largest. With the FT focuser a close second. Which will mean the optical axis of the modified filter stack. Has to be lifted even further away from the 6" objective's optical axis. Further increasing the demand for a shorter main tube. Just to ensure the correct optical spacing. Though with the added benefit of an even shorter instrument overall. 

 I would like to retain the primary FT focuser with its Baader Twist-lock clamp. This will provide stability and fine adjustability of etalon distance. The second Lunt-FT focuser is part of the original MT filter stack. Providing fine focus adjustment for the ZWO camera. It cannot easily be removed because of the unique interfacing with the etalon module. Will I run into vignetting problems? We shall soon see!

 Image left: First trial at optical folding using 2 x 2in star diagonals. No real attempt at getting the spacing precisely correct. Just ensuring it all fits together. There is a non-standard diameter on the front, Lunt etalon stub. I had to use my lathe to turn the inside of a 2" extension. Then groove it for the bronze clamping ring. This is the 2" Omegon extension.

 There is a Lunt 12mm, straight-through, blocking filter. Hidden inside the long extension just behind the second focuser. Most blocking filters are housed in solar diagonals.

NOTE EXTREME DANGER OF THE HEAVY LUNT COMPONENTS COMING APART AT THE PUSH FIT JOINTS!! The filter stack MUST be firmly bracketed to a main tube ring for safety. [Not shown.]

 Folding has saved roughly 44cm/17". On the length of the previously cantilevered filter stack. The folded OTA length is now 132cm. The straight version was roughly 167cm. All provisional measurements prior to exact spacing. Quite a saving in length. Making the OTA easier to house and to mount.

 I found the folded arrangement VERY unstable. Provided it is firmly attached to a main tube ring it should be manageable. Without adequate support there is extreme danger of thousands of pounds/dollars worth of equipment. Literally dropping like a stone onto the floor or the ground! You have been warned! 

 My original no-name 2" star diagonal has only one compression screw. Three screws would be much safer. To stop the whole assembly from rotating or falling out! The offset of so much weight 3.32kg or 7lbs makes the OTA want to rotate about it own axis. I shall probably invest in another Bresser 2" star diagonal if I can test the new optical layout somehow. I currently have no useful mounting.

 

  ~*~

7.08.2024 Swing that CAT?

 ~*~

  I wrote a lengthy post yesterday on options for housing my large solar refractors. Then deleted it when I had completed a new post on folded refractors. Folding my 6" optically would shrink it to far more manageable proportions. 

 The overlong H-alpha filtration on many modified, solar refractors is an acute embarrassment. Such a long stack makes it very hard to avoid sagging along its length. Though threaded fittings are stiffer. Most of us have to make do with push fits. Usually 2". Which is stiffer than 1.25" or T2.

 Shrinking the length of my 6" makes it much easier to house. Whether sitting permanently in an observatory. Or cowering under a run off cover. Observatory size is a very serious issue. No least on price. It also eats up the garden space when this is important. As it is to most of us.

 My back garden was no-man's land when I was building my foolishly tall observatories. Just to see over the hedges and my house. The latter sits unfortunately close to the southern border of my rural garden. The front garden is further reduced in width by the 7m long, lean-to greenhouse. So I have a strip of front garden only about 3.5m deep to play with. 

 Bounded by a beach hedge between myself and my neighbour's grassy paddock. I want to be able to push between the greenhouse and the proposed observatory. How else will I reach the glass? Besides, it is a long walk going right around the house. Just to reach the other end of the greenhouse.

 I could sneak a few more centimeters if I cut down the hedge and put up a fence. Not a good idea! The fence panels would warm in the sunshine and produce strong convection currents. Right in front of my telescopes. 

 The beech hedge is also more natural in its rural setting. Storms could easily damage a fence. Which the beech hedge would simply shrug off. The hedge is also a useful wind break. It filters the wind rather than accelerating and directing it. The height of the hedge is now mine to choose. The birds tell me they would much prefer a hedge.

 All of which brings me to the choice of accommodation for my telescopes. Let us suppose that the Pulsar 2.7m offers 2.5m internal diameter. The 2.2m only 2m Ø of clear space inside. A German equatorial mounting [GEM] swings the telescopes well off to each side. Rather than simply rotating and moving up and down like a fork mount. So it is no use [mis]calculating the required observatory size by telescope length alone. The telescope does not usually span the full diameter symmetrically.

 The swept volume of the extremities of the telescope[s] is an oval [lobe] on either side of a GEM. Because of the instrument's considerable offset relative to the Polar Axis [and the pier.] If there is a long filter stack, or useful dewshield length on a refractor, then this must be allowed for. 

 Ideally, one would mount the telescope[s] in an open space. Then drop a weighted line from the tip of the dewshield. Or from the camera on the end of the filter stack. Then mark out the shape on the ground as the telescope is swung from east to west. There would be a vertical component, of course. At least the clear diameter required for a cylindrical observatory [and dome] will be much better understood. 

 The height of the telescope dewshield, as it swings upwards, is also an issue. Requiring that the telescope's height be carefully arranged.  So as to be concentric to the dome's inner circumference. Otherwise the dewshield will strike the inside of the dome at certain elevations. Possibly at the zenith if the mounting is raised too high. The GEM's offset lobes to left and right must also be kept in mind. So the pier and thus the mounting height becomes vitally important parameters too. 

 The OTA can usually be slid along on its dovetail plate. Or through the mounting rings. Provided balance is achieved. Then a bias towards the lens or the focuser end. May help where tight clearance issues arise. Adding a weight to one end of the OTA can correct the balance if required.  Though care must be given to off-centre balance problems. The balance of the telescope on the mounting may change considerably. With different telescope orientations. Causing problems with tracking. Or even motor stalls on slews.

  

 ~*~

6.08.2024 Folding refractors:

 ~*~

  Tuesday 6th. Folding the 150mm/6"? 

 There is always the option of folding both refractors into more compact shapes. This reduces the size of the housing or observatory required. As well as helping the mounting. Many of which struggle with lengthy telescopes. Not due to the weight but due to their moment. Which is a term used in physics for mass [M] x distance [D] from the pivot.

 There is usually a heavy component at each end of a refractor. The objective in its metal cell and the focuser at the other end. This effectively doubles the moment. Since the majority of the weight is so far from the pivot point. [Mounting axis.] Add the considerable length of the filter stack and things get even worse.

 Classical refractors are normally of much greater focal length than modern, Newtonian reflectors. Though the tendency is towards faster [shorter] APO [apochromatic] refractors. Which often use special glass types to correct the false colours. From which normal achromatic refractors suffer. Which historically meant very long and unwieldy instruments. If only to overcome false colour.

 These older designs have a very high moment. Demanding large and heavy mountings. Often made of heavy cast iron. With very large slow motion gears.[wormwheels.] This made them unsuitable for amateur use. For those not rich enough to own a large observatory. The modern amateur often carries all of his equipment outside for each observing or imaging session. This demands light weight and compactness.

 I had already built a folded version of my 180mm/ 7" f/12. The same could be done for the 6". In this case only folding the tail end at the very beginning of the very long, H-alpha, filtration stack. 

 Two 2" star diagonals and a suitably long extension tube. Used as a spacer between them. Would probably do the job. To bring the filter stack parallel and close to the outside of the main tube. But pointing forwards towards the objective. The star diagonals safely avoid worrying about collimation. It is automatic thanks to the 90º bending of the light. By a mirror in a precision housing.

A main tube ring and connecting link could easily steady the folded stack. Though slight linear movement must be allowed for during focusing. A typical, felt lined tube ring need not be tightened unduly. So that it can slide freely along the main tube.

 The main telescope tube of the 6" might need shortening slightly. Or the FT focuser removed altogether. The distance from the focus to the Lunt 60MT etalon is critical. The primary focuser was useful for making these fine adjustments. Often in the hope of improved images.

 The ridiculously long, cantilevered, filter stack was already an embarrassment! I had to provide support in the form of a rectangular, aluminium tube. Not easy to attach to the stack. Because of the need for linear movement and the rotation of the OTA over time. Sagging of the multitude of push fit elements is almost inevitable!  

 I only have one [no name] 2" star diagonal. So I have ordered a Bresser 2" star diagonal. To experiment with possible folding arrangements. The Bresser has "only" 93% reflectance. Compared with the usual 99% claim for the dielectric diagonals. Which hardly matters with the intense solar energy available in a 6" refractor.

_____________________

 My 180mm/7" badly needed remote, screw adjustment for the 2nd folding mirror. Bringing the adjustment back, via rods, to suitable knobs on the telescope back plate. Without which collimation was a nightmare! I went back to the straight tube version instead. Before finally giving up.

 My massive mounting struggled with the weight of two [or sometimes three] OTAs. All down to the weak worm housings. The Ioptron CEM120 could probably manage both 'scopes by weight alone. Though only if they were optically folded. Folding has the advantage of greatly reducing the moment of a telescope.

Moment = mass x distance from the pivot point. If the mass doesn't change. Then the moment is reduced by bringing it nearer the pivot. i.e. By physically shortening the telescope. Though there is usually some small increase in overall mass due to added components. The distance at which the weight lies from the pivot is more important than the weight. The classic big kid, little kid on the seesaw.

 The moment of an equatorial mounting can be similarly reduced. By using more counterweights and sliding them towards the body of the mounting. This may help where the weight limits of a mounting are reached. Particularly with long and heavy refractors. Hanging fewer weights on the very end of the axis shaft may be a poorer choice. Unless you really want to save weight with a mobile set-up.

 

  ~*~

5.08.2024 Oh No! He's at it again!

 ~*~

  9.30 I have been back outside looking at the sun through my Lunt LS60MT.  I am using an old black T-shirt over my head. To shield my eyes from stray light. This really helps to show fine, surface detail and proms.

 I keep wondering about having a fixed pier. Which is a very good idea for imaging. No setup time or polar alignment. Point the telescope lens down and remove the long filtration stack. Now it is far more compact for storage when not in use. A weatherproof box need no longer be as huge as a domed observatory. A simple "sentry box" is all that is required. 

 Another infra red image. Showing a cool hedge after many hours in the sun. Cool grass in the foreground. Warmer weeds near the ground. Odd? Warmer gravel. The green rectangle surrounds a roll of foam backed aluminium foil. It is cool except where it reflects the sun directly to the camera. A good result. Some solar imagers wrap their piers and mountings in this material. To avoid heat build up spoiling local seeing conditions. Convection currents from hot objects could rise through the light path. Causing movement and distortion in the image.

 Is the expense of a domed observatory really such a good investment? The cost is absolutely horrendous! The alternatives not very ideal. The dome provides maximum shelter from the sun and the wind. Further improved with shutters over the observation slit. Above and below the telescope objective.

A roll-off roof building offers only very limited protection from the sun. Only then if the imager sits in the shade of the front wall. There is much less shelter from the wind when the roof is wide open. 

 A new idea: I already have a large building for personal shelter. In the form of the lean-to greenhouse. If  the telescope is pier mounted outside and driven. Then I do not need to be physically close for adjustment. Electric focusing is already arranged. Just needs power.

  I could sit behind the telescope in the greenhouse. Where I could watch the telescope and have my computer monitor and desk. The greenhouse is more comfortable than any open observatory. I can provide solar shade in the form of the nets I already use. I have the mesh covered secondary doors open when it is warm. Providing a comfortable, through draught when there is a breeze.

 This still leaves me with the problem of protecting the telescope from the wind. Removable panels could be arranged on either side, as appropriate, at hedge height. Cloth slows the wind but is not like a solid wing. Too fussy?

 Or, I could have a secure, roll off building. Or roll-off roof. Both of which can be moved to the west as needed. How to maximize wind protection from such a structure? I'll have to think about this. A housing which only needs to look out from east to west via the south. 180º maximum.

 Here we go again: The Calf-O-Tel Plus. A white, fibreglass, roll-off observatory? About £450 equivalent. 😀

• Længde: 196 cm
• Bredde: 115 cm
• Højde: 128 cm

 Stand it on its open end and add some rails for mobility and security against the wind. Add a secure door to what was the open base. What more could you want? A bigger one? This would make more sense:

The CalfOTel Comfort:

• Længde: 200 cm
• Bredde: 120 cm
• Højde: 140 cm

This  one is big enough to house the telescope when parked E-W. About £650 equivalent. The threshold would prohibit rolling away from the pier. Not sure it is a permanent fixture or only fitted for movement. Wouldn't the calves would trip over it if it were always there?

  The XL2:  is designed for two calve and provides greater width. The XL2 is a bit overkill for a roll-off shelter. It is almost observatory sized but without an observation slot.

 The narrower hutches are more attractive as roll-off secure shelters. Their limited height demands off the ground supporting structure and rails. They would NOT reduce the wind buffeting the telescope[s] in use.

 I have emailed CalfOTel in the Netherlands for unit weights. The larger Comfort and smaller Plus hutches each weigh about 35kg. YouTube videos show single persons lifting these smaller hutches manually. Even when fitted with steel work. Certainly doable within the limited space of the front garden.

 

  ~*~

4.08.2024 I don't believe it! H-a observing?

 ~*~

  Sunday 4th. I can hardly believe it! Early thunder and rain, then brief sunshine. Now there was the threat of a very large sunspot. 

 This drove me to collect the various bits of my Lunt LS60MT together into a useful bundle. The H-alpha parts had been greatly extended and attached to the 6" up in the observatory. So had become separated from the objective and its stubby main tube. Once assembled indoors I plopped it onto the Manfrotto tripod,. Then dragged it outside and waited. And waited. Heavy clouds blocked most of the sky.  

 Finally, I had my first view of the H-alpha sun in a very long time.  

 12.00 I upped the power progressively. Until a no-name, 10mm Plossl provided a nicely crisp image at a nominal 45x. I added a TS 1.25" star diagonal for lots more comfort. The sun was high in the SE and my neck had been complaining. No matter how I adjusted the tripod up and down. 

 The multiple splodges of the scattered sunspots were clearly visible. The large spot, coming around the advancing limb, seemed less dramatic. Now it had cleared the limb. Meanwhile, blue holes had steadily increased in the heavy cloud cover.

 12.40 Brief sunny periods at the moment. The afternoon forecast looks much more promising. I'll have lunch and then go back out again.

 14.00 Heavy overcast! All afternoon!

 Sitting on a patio chair on the open lawn and viewing the sun reminded me of two things. There is "dome seeing." From the observatory heating up in the sunshine and causing thermal currents in the air. There is also dome shelter. Which protects the observer/imager from direct sunlight and the wind. And rain of course. Though the latter usually results in closing the shutter(s.) Taking only a few moments compared with rushing indoors with armfuls of equipment. 

 This is the most telling reason for having an observatory. There are others of course. No need for polar alignment providing one has a permanent pier and an equatorial mounting with a memory. Starting up and switching off afterwards should be reduced to a minor irritation. Instead of a complete workout.

 Reading back though my past blog posts. Confirms that I really struggled with highly variable seeing conditions. The plywood dome cladding was certainly a great, solar heat absorber. I had tried draping white tarpaulins. To block the sun. Though with only very limited success. 

 This infra red image is from the other day in bright sunshine. The cool contrast of the vegetation. Compared to the bare plywood of my observatory and shed is truly remarkable. Even the sparse grass in the foreground keeps the ground cool. 

 Just beyond this is the bare gravel. Which is much warmer. Locating a solar observatory looking out over grass makes obvious sense. In reducing local convection currents in the long light path from the sun.  

 Note how cool is the shiny, aluminium tripod ladder. Suggesting a shiny aluminium dome would be much cooler than a plywood one. I shall have to find some white GRP somewhere to photograph with the infra red camera.

[Image from my One+ phone fitted with a USB-C, plug-in, Topdon TC001 infra red camera attachment.]

 Larger apertures are increasingly susceptible to poor seeing conditions. No doubt white paint would have helped. At that time I was against painting the observatory white. It stood out like a sore thumb from the distant road. I didn't want to attract attention.

 A dome is fairly good at protecting large telescopes from the wind. Depending heavily on the wind's direction and the position of the sun in the sky. There were many times I had to dress warmly to cope with a whirlwind in the dome. Despite my massive mounting the telescopes still shook in the wind. Mostly due to end float on the flimsy and badly designed, commercial worm housings. 

 Forum members have expressed doubts. About the wind resistance of the Ioptron CEM120 mounting. This has spring loaded worms but only 216mm [8.5"] worm-wheels. The CEM120 can certainly carry heavy weights. Though its exact design details. Might limit its use in very exposed circumstances. 

 If I should decide to invest in this mounting I should seriously consider its protection in use. I cannot see it performing well out in the open. My front garden is subject to the SW prevailing wind. The raised observatory was rather more fortunate. Due to the shelter provided by all the trees to the west and southwest. The front garden is unprotected beyond the head high, beech hedge. Plus the shrubs I have allowed to grow almost out of control. Mainly to provide interest through the kitchen window and to shelter the greenhouse.

 

  ~*~

3.08.2024 Will the real Pulsar dome please stand up?

 ~*~

  Saturday 3rd. The very high cost of owning a Pulsar observatory made me wonder. Whether I could improve my present but very leaky 3m dome. The plywood surface badly needs to be sealed. Particularly at the joints.

 I could have the local crane hire lift the dome down onto blocks. Where I could safely fibreglass over the plywood. This would add even more weight. Though I would able to work on the shutters from the safety of the ground. They need attention after years of exposure to the weather. Access is presently difficult, dangerous and very exposed. While the dome is in situ on top of the two storey building. 

Once I have the dome waterproof and cosmetically acceptable again. It could be lifted onto a square building in the front garden. Fiberglass layup is a smelly, expensive and time consuming pastime. The resulting dome would be rough on the exterior from the chopped strand mat. Sanding would not improve the surface finish by much. GRP dust is horrible stuff! Itchy and probably dangerous to inhale. A really nasty job. 

 One option would be to buy aluminium sheet. To replace the warped plywood covering panels. This would require very careful bending to match the geometric forms. None of which are exactly the same size! One might as well build an aluminium dome from scratch.

Then there is the "Todmorden" barrel dome. A sort of rotating Nissen hut with sliding sections. To provide the opening [observation slit] for the telescope to see out. This has the advantage of providing lots of room for the telescopes to swing inside the "shoulders" of the protective structure. It can be built of aluminium or [probably] plywood. Having so few joints, compared to a hemispherical dome, should make it more waterproof. A simple lap joint at the roof overlap will prevent rain from running straight inside. There are numerous illustration of their barrel domes on their website.

 https://www.astronomycentre.org.uk/

 Another alternative is to buy just the Pulsar dome on its rotation, base ring. This would be lifted onto a square, timber and plywood box building in the front garden. Saving about £1370 [equivalent] over the purchase of the full height, Pulsar observatory with walls. I'd have to do some checking to get an exact figure. The freight charges might be a bit lower too. 

 The dome-only option from Pulsar. They have some considerable confusion over their dome illustrations online. This is probably the 2.2m. There are too few rotation roller brackets visible for it to be a 2.7m. The usual drop down flap, at the bottom of the observation slit, is missing. Perhaps suggesting a Mk2 dome? 

Who knows? Pulsar doesn't seem to. Most of the international website sales illustrations are for the earlier domes. So anyone ordering one without doing some homework will be very surprised at what eventually turns up! Even Pulsar themselves are showing the two sizes on the same page on their website!

 I have loads of materials to build the walls for a square box base. No additional equipment bay would be required. Since a square box provides lots of extra space in the corners compared to a plain cylinder. A dome-only purchase might need only one [very expensive] pallet. I would have to inquire of the European dealer. 

 There are always cons: A square, box room base would fill the front garden far more than a cylinder. It would also block the light to at least one living room window and to the greenhouse. Squeezing between the building and the greenhouse would be far more difficult than walking past a smooth cylinder too. The grooved plywood I use for cladding is too stiff to follow a curve. Though it might be made to do so with tensioned, ratchet straps.

 

  ~*~

1st August 2024 Pulsar 2.7m observatory pricing. [August 2024]

 ~*~

  Thursday 1st.

 I heard from a European astro dealer giving a delivery charge to central Denmark for a complete Pulsar 2.7m observatory:

Delivery charge €1035 + VAT = €1294 = 9700DKK = £1097. This is just for delivery by freight forwarding. 

The observatory alone would cost 61200DKr  = €81200 = £6923. [£5295 in the UK]

The equipment/accessory bay adds 4850DKr = €650 = £549.  [UK £449]

So dome, including walls and bay = 66050DKr = €8850 = £7473. [UK £ 5744] 

Total incl. delivery = 75750DKr = €10150 = £8570. The difference between UK prices and Danish is probably due to import & VAT charges.  Denmark's VAT is 25%. German VAT is currently 19%. After Brexit there are import charges for UK made items to the EU. 

 Though I thought I remembered that those buying outside the UK need not pay UK VAT. The VAT and import charges are payable in the country of the purchaser. The huge differences here suggest double VAT payment. Perhaps it is the markup by the EU dealers.

The [UK prices in brackets] do not include delivery. Which will vary with location.    

I was quoted 6-8 weeks for delivery.

~*~