I'd decided long ago that having everything set up to go was the key to getting out more often, but not having a lot of space to play with in my back garden, I'd written off ever having an observatory as such, and settled on a pier for my 8" Celestron SCT, and 66mm William Optics/80mm Helios refractor wide-field rig which I usually operate on a Heavy-Duty Celestron Tripod and CG5-GT goto mount.
I'd got to the point of constructing the concrete-filled pier with a standard EQ5-style head that I was about to built the foundations for, when out of the blue I had the completely unexpected opportunity to acquire a 10" Meade RCX400 Ritchey-Chretien scope to complement the smaller scopes. Having done a quick mechanical test, spent a few hours of re-greasing and cleaning and a nighttime optical test run that confirmed its first-rate optics, the Meade was patently too good to turn down. I can honestly say this is the first of many scopes I've looked through that I would say "blew me away", and I'm genuinely grateful to the previous owner for passing it on to a good home, at such a good deal. I hope to give it the use and care it deserves and look forward to inviting him around to try it out as part of the deal !
As big as it was, I wanted to add more to it to use it for astrophotography: my plan was to add a Starlight Xpress filter wheel to my SXV-H9 CCD. I've been learning to use this camera in monochrome all winter on the WO ZS66SD/ Helios 80mm rig mentioned earlier, but having collected two superb sets of Astronomik filters over the last six months (a Type 2c LRGB set and an Ha/Sii/Oiii narrowband set), I'd like to try moving on to colour imaging. I might even give my SXV-M7C one-shot colour camera a try again once those fine guys over in Maidenhead build me a new power board to replace the one I blew up by plugging my 'H9 into the '7C power supply !!
Anyway, the key point as some astute readers will have picked up, is that for photo work I'd need to add a wedge to make this Alt-Az scope equatorial, so the whole rig was only going to get even physically bigger. I checked out many, many websites, and the consensus was that the Meade wedges were very occasionally weak due to casting defects. So after a bit of research I decided that what I really wanted was a Kentish Astro-Engineering wedge, and after a few weeks trawling and scrutinising Astro-Buy-and-Sell, exactly what I wanted appeared. A short drive over to Windsor and a fellow backyard astronomer had some extra finance towards his next project, while I had a cracking Astro-Engineering Mega Wedge to add to mine.
I spent a long time deciding where to locate the scope, as if I couldn't keep it secure I wouldn't really be able to justify buying it. The worst outcome would have been for me to take it, and then not use it because it was too much hassle to set it up. My conclusion was that I would have to locate the scope near the shed where I put my computer so that power and USB cables etc. are all accessible, and that it should be possible to set up for imaging in around five minutes. I was delighted to find that it is completely independent as far as alignment in Alt-Az mode is concerned, taking less than five minutes to self-level , find north and align to two stars using GPS and the in-built accelerometers - verrryy impressive !! However I'm yet to establish whether it can do the same in Eq mode. So outside the shed it had to be.
About twenty buckets later I had the foundations below:
I then established that the spread of the tripod at minimum extension is 120cm. The tripod on this thing is a solid lump of aluminium weighing about 60lbs (27kgs) - I lost one of the spacers for the fixing bolts and nearly broke my foot when one of the legs fell off onto it as I carried the tripod out of the shed to measure up ! A good turn from a mate up at the workshop in Notts. University got three replacement spacers with me in a couple of days - many thanks Dave !
Next I assembled the lot to make the trolley up - you can see the new paving still drying out too. I'm going to use turnbuckles at two corners, with 6mm wire rope to tension the trolley diagonally, watch out later.
Incidentally, I used M10 studding and bolts/washers rather than buying coach bolts as it's cheaper, and also I may later add a level of marine ply on top of the trolley for rigidity if needed, and the studding leaves loads of extra length if needed. You can also see the tripod on top - although the tripod is about 60lbs, the wedge another 70lbs and the OTA/fork 90lbs (total a massive 220 lbs, 100kg), I'll be using another turnbuckle with wire ropes to winch the telescope to the trolley.
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Our lovely British Bank Holiday weather was as predictable as ever with glorious sunshine one minute and horizontal rain with added hailstones the next, so much of today's construction took place under tarpaulin:
Just to make sure that the scope was going to fit, I thought I'd check on how tall the whole thing will be when assembled. Rather than take the chance atthat I'd drop the scope when trying to attach it to the wedge, I measured a bit of bamboo to match the distance from the base of the fork mount up to the top of the OTA, and then stuck that into the wedge on top of the tripod, on top of the trolley. The thing is going to be HUUGE - the blue mark on the bamboo marks the top of the OTA in parked position - I'm not certain it'll all fit !!
Oh well, looks like this telescope house is going to need to be a shed extension to fit in. Base and first upright secured to the shed, on to the next phase next week ...
Here's what I'm up to so far. Interestingly, while making everything square and plumb I've discovered that everything else in the garden is out of whack :-)
My latest thought is to keep the option of an open roof by building a sliding roof ... not quite sure how yet but I have a few designs in mind, and ordered up eight 50mm polystyrene wheels today. In construction terms, I moved on a little by starting the external cladding. Should finish this at the weekend, and get onto the doors and first phase security features. Well I'm not going into detail on these for obvious reasons, but the telescope house will be (along with the other outbuildings), wired into the house security system, so the general theory is for it to take longer to break into the telescope house than the security service take to get here. The design has lots of features to make life *really* hard for any scumbag burglars :-)
The design of the double 2"x2" verticals with carriage bolts should now be clearer - once the rear cladding is complete, I can unbolt the whole rear panel and treat/paint it whenever necessary in the future (flatpack in reverse !)
With a bit of inspiration, it occurred to me that with a bit of thought and planning I could build the roof in such a way that I could install the sliding system at a later date. So here's the result - roof built and felted, now just need to add the doors and trolley rails before it's ready for use. Might be later in the summer before I detach the roof and fit the sliding mechanism.
More good news today - I decided to do a quick test to make sure the scope would fit before starting on the doors, and having set the wedge to 51-degrees, found that I have about a foot (30cm) extra headroom. I knew that the wedge wasn't set properly before and expected to gain some extra but thought it wouldn't amount to more than a couple of inches. I hadn't mentally factored in the fact that the fork and tube is 90 cm long so a bit of adjustment makes a lot of difference. This is really good, because it means I'll be able to store the scope with a guidescope permanently attached. (Note: I just realised that I had my angles wrong - I should have set it 51-degrees off the vertical, not the horizontal. Oh well, should still have an extra six inches or so headroom).
The directions match up well too, in the pictures below the wedge is correctly pointing due south, and the tripod fits bang in the middle of the trolley.
Last night I tried the scope out for the first time in ages, now in its new house. Polar alignment was pretty straightforward, never having done it on a fork mount before I was a bit apprehensive but it went fine. I spent an hour just cruising around the sky: even though imaging shows so much more, I'd forgotten just how cool it is to see the sights first-hand through the eyepiece. Fiery-orange Arcturus looked superb, and M13 was looking magnificent until my power supply went nuts and sent the electronic focus into a tailspin. I'm going to chuck the power supply in the bin and use my 13.8V bench power supply instead. Just need to drop Andy at Astronomiser a note to buy one of his great power cables.
I finished the doors today and hooked the shed up to the house security system. The heavens then opened for the rest of the day, so I think I'll just leave the roof bolted on until the weather clears before converting it to a slider.
This is the end of this build phase, next onto hooking up the electrics and connecting the scope up to the cameras, getting autoguiding working etc.
Fun and games today adding the rails for the guide scope and counterweight, tricky to get the balance right but the motors don't seem to notice any difference.
Fitted the telescope house with its own electricity and lighting today so I can leave the scope permanently hooked up for grab'n'go visual work without opening up the shed and plugging everything in. Looks like a dodgy nightclub at the end of the garden tho' (or somewhere even dodgier :-)). I've recently shipped an Astrozap dewshield and cover in from the U.S. too, but now the scope is out of balance again, so I'm waiting for a 3-D balancing kit to arrive. Should be set up for the autumn then I reckon !
