Where shall I start? The project is still not finished but an end is in sight. After the last post, I built the roof frame and managed to lift the roof into place on my own. I figured if the ancient Egyptians could build pyramids I could lift a roof. I’d be lying (again) if I said it was easy. A steel roof 10′ x 10′ with a wooden frame weighs … well lots, and lifting it into place required me placing wooden rails either side and physically lifting the roof past the tipping point to allow it to fall into place. I stopped for a breather after that!

With the roof in place I was able to complete the walls and fascia boards and move onto the rear rail assembly that will support the roof in a “rolled-off” position. Digging 2′ holes for the fence posts was easy enough, trying to hold a post upright and level whilst aligning it with the roof rail (which I couldn’t see) proved to be to too difficult and I eventually built the whole rear assembly upside down on the lawn. After my Herculean efforts with the roof I asked my brother to lend a hand to carry this into place. With a lawn that slopes making everything square and upright was a task. I propped the ends of the main framework on timbers to get it level before fixing the upright fence posts in place. A slight error on my part means one of the posts is not perfectly upright – but close enough. The photo makes it look worse than it is because the steel cladding on the shed runs out slightly where the fascia board pulls the top in. No really – I’m not making excuses.

So where are we – roof in place – rear assembly in place – oh I know what I missed: After getting the roof in place the heavens opened and it rained like I should have built an Ark not an observatory! To my horror the roof leaked. The only reason for buying the steel shed was to make sure the structure was weather proof! Ahhhh. I spent an afternoon with buckets and silicone sealant trying to make running repairs but the silicone washed out but luckily the buckets kept the floor from getting any wetter than it was. The floor wasn’t sealed, it’s made of a type of board that isn’t weather proof and the damp barrier was under it, so when the boards got wet I did worry a little. After several attempts to repair the leaks I got my brother over to help lift the roof off – the once heavy roof was now even heavier as the rails and cross supports where now in place! In hind-sight it was a 4 man job, but by the time we realised that we were past the point of no return. We stripped the roof boards off and re-assembled them, this time with a thick layer of black sticky roof repair goo between each joint and in all the screw holes. On either end we used roofing bolts instead of the provided screws and washers (these are self-tapping bolts with a built in fibre washer). Black goo oozing from the screw holes was dismissed as a necessary evil and the rebuilt structure was manhandled into place, now all I needed was rain to test it.

As luck would have it I didn’t have to wait too long and again AHHHH it leaked! Only in two places, 1 was a screw hole, the other a seam between 2 of the roof sheets. I fixed the screw hole by removing the screw and putting enough black goo over the hole to plug 20 holes, but better safe than sorry. The seam was another issue. The problem was where the sheets overlap. I ran a bead  of goo down the whole length of the seam and screwed through from the inside – pulling the two sheets together with goo squeezing out both sides.

So the roof is on, the rear frame in place – no leaks? still waiting for significant rain to test it – on to the wheels and rails. Running castors on a wooden beam will quickly wear a groove, I decided to buy some steel channel for the castors to run in. I decided 4 castors each side would be enough -  and if not I’d put some more on. Not exactly a scientific approach – but it worked. So how do you screw castors to a rail that’s upside down and weighed down with a roof. I have these clamps that work by pulling on a trigger to close them and pressing a release button to unclamp. by removing one end of the clamp and putting it on the other end it becomes a spreader! I used these to lift and hold the roof with wooden blocks just in case the roof fell while my arms were under it!  The steel was easy to work and I drilled and counter sunk the holes until I broke my counter sink bit, then I used the 20mm bit I’d used on the brake disk as a counter sink – that was fine. Rails in place, wheels in place – paint applied to all exposed steel – now it’s taking shape. Before the wheels and steel rails I was able to haul the roof back a few feet, but now I was able to run it fully off with one hand!

Exterior timber has been painted with wood preserver and the floor covered with wood-oil to waterproof it. I’ve built a wide shelf along the back wall to hold a laptop and any other bits and pieces. I’ve also run an armoured power cable the length of the garden and wired up a consumer unit with RCD and 4 x 13amp power sockets. I have a 6amp circuit for lighting but don’t have a light yet!

So here’s a few photos:

	Here’s a shot of the mount in place. I tried it to make sure it pointed north but the clouds came over before nightfall so I couldn’t get a sighting on polaris.  I’m happy there’s enough adjustment to get it aligned, even if the pier alignment is off.
	Here’s a shot of the observatory (careful not to call it a shed!) with the roof off. Construction still taking place so it still looks like a building site.
	Here’s the latest shot of the outside of the observatory.
	The locking mechanism. Likely to be a temporary solution while I  look for something more permanent. The clamp stops the roof rolling off and also keeps it down. I’ve also added some other clamps and locks to keep it all secure.
	Here’s a panorama of the inside of the shed at eye-level. It shows castors, rails, clamps and black goo if you look hard enough

Update 19:05 25-04-2010:

I’m done! I painted the pier and the brake disk, installed a power-line Ethernet adapter to give me network access and fitted a second hasp to the door. I bought 2 padlocks and fitted them as well as some other bits and pieces to help secure the structure.

All that’s left is to find a spanner that will fit under the brake disk to tighten the centre bolt that holds the mount in place. Nothing too serious but without this simple tool I can’t do any more. When done up the bolt is slightly recessed into the brake disk making it difficult to get any type of adjustable spanner (wrench) in there. It’s cloudy tonight so no rush – you can be sure it’ll rain for the next 2 weeks!

Hopefully the next post will be first light at Ty Du Observatory.

Watch this space …

• put the shed walls in place
• removed the cardboard column form – to find my attempts at preventing air bubbles had failed
• built an internal wooden framework
• installed the floor and 3 walls
• secured 2 wooden rails inside the shed for the roof to run on

I’ve run two 4″x2″ rails from front to back to support the roof. These rest on 3″x3″ fence posts which are secured in the ground using post supports (metal spikes that are driven into the ground with a box section on top to receive the post). The roof will have corresponding rails and these will be fitted with castors to allow the roof to run easily. At present the rails only run to the back of the shed, these need to be extended outward to support the roof in the “rolled off” position.

I’ve received delivery of timber today to complete the roof by installing an internal 3″x2″ framework onto which two 4″x2″ rails will be run but have been unable to continue with the build due to the weather. It’s been dry since the project began, but there was some fine rain yesterday and “proper” rain today. Hopefully it’ll be dry enough tomorrow to install the roof which can be clamped in place while I complete the inside of the shed. I’ll look into making the roll-off frame either this weekend or if I can’t do it this weekend it’ll have to be next as I’m back in work on Monday.

No photos today, but I’ll do some when the rain stops.

• Finished laying blocks on concrete as the footer
• Cast the column – that was a big moment

Filling the column form took more concrete than I’d anticipated but I had enough materials to complete it without a trip to the DIY store! A worry of mine was how to compact the concrete within the form to make sure it’s as solid as possible. I used 2 methods. Firstly I used a length of timber to push the concrete down, especially the first couple of shovel fulls, to make sure all the gaps were filled in around the reinforcing rods. Secondly I inserted a right-angled bolt, I think I salvaged it from an old stair gate, into my cordless drill and used the asymmetric motion of the bolt to act as a vibrator to remove air bubbles. I used this against on the framework and also on the top board to effortlessly sink it into the concrete.

All I have to do now is assemble the shed over the column and turn the roof into a roll-off! Easy – I’m not expecting it to be too easy but I’d rather work with a wooden frame than lay concrete blocks!

I bought a bubble level to level the top board and I think that was definitely £1 well spent. Trying to get the column form upright would have been impossible without it. There’s rain forecast today but it should be dry over the next couple of days so hopefully there’ll be an update on Sunday.

more to follow…

• dug a hole 600×600x600mm
• hammered steel rods into the walls of the hole for stability
• filled the hole with concrete
• inserted steel rods in the centre of the concrete where the column will be cast
• started laying foundation blocks
• started assembling the steel shed

I should be able to cast the column either this evening or in the morning after which I’ll continue with the foundations. I’m only using a single block foundation as there’s no weight in the shed and it’ll be supported internally by a wooden frame.

Here’s a before and after shot showing the location of the observatory:

I can’t believe that since dismantling the mount we’ve had the clearest night skies for months. I just have to console myself with the knowledge that it won’t be long until I can take advantage of any gap in the clouds

More to follow…

Putting this minor distraction to one side, the column form will be held in place with a wooden cage (I’ve made that) which will sit on wooden beams laid across the base pit.  The pit will be approx 900mm cubed with the column rising from the centre. I’ll level the cage by driving timbers into the ground at angles then screwing them to the cage to hold it upright. This will have to be done on the day of the concrete pour to make sure everything is as perfect as I can get it. When the concrete is set I’ll build my self-assembly steel shed around the column. I’ll build a wooden frame inside the shed extending to the rear to allow the roof to be slid off.  I’ve found a few examples of this being done online but my favourite, and the one I’m using as inspiration is the Linnhe Observatory in Scotland.

Rather than cast a concrete floor I’ll be laying a waterproof membrane and building a raised wooden floor. The observatory will be for the most part remotely operated so there’s no need to build in creature comforts however I will be including storage for all the astro odds and ends that I’ve collected.

I’ll update this as the project progresses …

A view of the column top. The wooden plate will be removed after the concrete has set leaving a spanner sized gap for tightening the bolt that will hold the EQ6 in place.

This is the tripod top sitting perfectly in the brake-disk. If only I could weld it there. Plan B may involve drilling in from the sides and bolting the two pieces together. Unless I can find someone with a tig welder?

Anyway, the reason why I thought I’d write something today is to let everyone know that I’m about to build my own roll-off-roof observatory.  I’ve purchased a metal shed which is approx 10′x10′ (3m x 3m) and after searching everywhere for a round section column form to cast the pier I’ve decided to make my own mould from ply which will give a square section, but I have the ply so I can make it at no cost.  I’ve booked 2 weeks off work in March to do the build so I’m currently in the planning stage.

My wife managed to topple the mount this week which luckily didn’t hit anybody or anything on the way down and the only damage appears to be a broken locking lever from the weight shaft.  Its a black cast component that fits over a brass square topped bolt.  I’ll make a new lever when I get a minute. I won’t know if there’s any internal damage until my next viewing/imaging session – fingers crossed.

I’ll take photos and make comments throughout the build so keep watching for updates.

Here’s the mask (it’s not really this colour):

The tabs on the side bend over to “hook” over the top of the scope, but in use I had to use some masking tape to hold it in place.

The resulting image when out of focus clearly shows 3 separate images for dimmer stars but shows six large spikes on bright stars like Arcturus here:

When in focus the the 3 images become 1 and the spikes on the bright star become very clear:

The secondary vanes still make spikes so I get an extra 4 to help focusing.

So after focusing the camera (and I think it could do with another tweak), I took a few images before the battery ran out.

M3 Globular Cluster

M13 Globular Cluster

M27 The Dumbbell Nebula

NGC6946 Spiral Galaxy

I’m disappointed that even with 3 minute exposures NGC6946 is still very faint.  With the Atik 16ic this galaxy was brighter using 1 minute exposures – but that’s the difference between a CCD and a CMOS camera I guess.

Next time out I’ll see if I can get the focus even sharper.  I’m also trying to work out how to get the 2″ LPR filter I bought into the light-path given that the camera adapter doesn’t have filter threads.  I’m so glad I haven’t bought a coma corrector yet as this would screw into the same non-existent threads!

I took a couple of 5 minute frames across the “mexico” of the North American Nebula (NGC7000) but they won’t stack so I can only view the frames individually. I’m sure I have caught some nebulosity and comparing my image with others I can make out some structure, but I think I’d need to take lots of these, on a clear night with good seeing and better focus to make anything worth showing here. Maybe next time.

Here’s a quick and dirty draft image using 14×120 second frames and 1 dark.  I’ve streched and tweaked the image to try and bring out the detail in the nebula, but its still very faint on the left of the image.

The Veil Nebula (NGC6960)

Hopefully I’ll be posting a better image here after I’ve got all the data in.

Another quick effort before wor. I managed to get another 10 shots but DSS only stacked 35 of them.  There’s more detail in there I just need to tease it out using photoshop.

The Veil Nebula (NGC6960) 35x120 seconds

I have another dark frame to add to the stack but I don’t have time at the moment.  Maybe later

Update: Saturday 26th September

I was able to create flats and bias frames as I leave the camera connected to the scope so the light path hasn’t changed since these images were taken the other night.  Reprocessing has annoyingly made things worse not better as there seems to be some structured noise that is accentuated by the new processing.

Example of noise

I’m guessing the noise is a result of imaging at iso1600 rather than adding flats and bias frames but only time will tell as I take more images. Unless someone knows the answer and would like to make a comment

I’m currently trying the same flat frames with the Veil image from the 12th as I’m sure the flats will remove the bright area on the image.  I opened the combined flat in Photo shop and stretched it to find an exact match for my bright area which I may have blamed on coma in a previous post. The iso value of the flats doesn’t match the iso value of the lights so I’m not sure I’m going to get anything, but I’ll keep trying.

—–End Update —–

Session details:

Imaging: Canon 300d (unmodified) – Skywatcher 250 Newtonian scope on EQ6Pro mount

Guiding: PHD -Atik 16ic on 60mm refractor

Processing etc: EQMod, Starry Night, Canon Remote Capture, PHD DSLR Shutter, Deepsky Stacker and PhotoShop CS2

Clearer than last night, there doesn’t appear to be as much high cloud. I’ve been shooting for the last 2 hours but I’m not happy with the focus so have just returned from making a few adjustments. Fingers crossed, it’s a bit hit and miss trying to focus on stars through the view finder on the camera, but I think I’ve improved things.

Here’s M81 (before changing the focus).  It’s too close to the meridian now to start taking more shots so I don’t have anything to compare with it.

M81 (Bode's Galaxy)

I’ve moved on to the Spindle Galaxy (M102) which is very small in the Canon’s field of view so I don’t know if I’ll get anything worth showing.  On the Atik16ic the spindle didn’t quite fit in the frame, I used to try and get it across the diagnal, but now it’s a tiny blur in the middle of the frame.

Hmm, not too happy with the M102 results so far. I wonder if I can fine tune the focus on something like M13. The globular clusters have enough stars to allow me to find a round star (given the amount of coma I have) somewhere that I can focus with.

Scrap all the images I’ve taken over the last 90 minutes or so.  The trouble with changing the focus is that its not an exact science, especially when you have the standard skywatcher focuser  It looks like I was a fraction out, but more so than I was before.  I finally managed to get it closer by changing to 10 second subs on M2 using the small JPG option.  This allowed me to quickly (20 minutes) change the focus, take a shot, change the focus … you get the idea.  I’m now taking a short series of M2’s in the hope I can prove to myself that the focus is indeed better than before.  The wind has picked up now though so I have even more variables to contend with.

M2 Globular Cluster

After M2 I turned back to M27.  I was pleased with my previous efforts, but I think the new shots are much better.

M27 (Full Frame)	M27 (close up)
After changing the focus and reducing the exposure time I have much better star shapes across the whole frame.	The nebula cropped from the previous image.

Here’s another NGC6960 – The Veil Nebula (West). I tried shorter exposures but more of them. This is 26×60 seconds from a set of 35.

The Veil Nebula (West)

NGC6946 is a galaxy that I often come back to. Last year my images were used by Belfast University as I’d managed to capture a super nova event before the big boys turned their scopes in that direction. The Atik does a better job of bringing the detail out, but it’s another view of an old favourite.

NGC6946

M52 The Scorpion Cluster is one that I caught with the Atik some time ago. I’m not a huge fan of open clusters (because they didn’t fit in my FOV!) but this one fits nicely onto the Canon sensor.

M52 The Scorpion Cluster

M31 The Andromeda Galaxy has just made it past the meridian, but the battery has run out in the camera. I only managed 3 frames but it’s now 03:02 and I don’t think I’ll change the battery – I need some sleep.

M31 The Andromeda Galaxy

I even got the bonus galaxies M32 and M110, that wasn’t planned

I’ve just been reading some articles on DSLR Astro work and I think I need to start looking at BIAS, Darks and Flats.  I’ve used Dark Frames previously with webcams but didn’t need them with the Atik. On my next clear night I’ll try and do things properly.

I took some more shots of the Veil, but when viewed through cloud it’s not easy to make out even with 10 minute subs! M3 was a starting point, with M101 next. M101 was very faint and I should have realized then that something was not right. It’s usually bright on short exposures but 17×90 second frames wasn’t enough to show any of the detail on this spiral galaxy.

M3 Globular Cluster	M101 Galaxy 17x90 secs	The Veil Nebula (West)
		I’ve really stretched this to bring out the wispy strands of the nebula, and in so doing have accentuated the bright area that appears in all my Canon images. I think this is something to do with the collimation of the scope and/or the camera being slightly off the central axis of the light path. Maybe when I get a coma corrector it’ll go away