The Leo tripet is a small cluster of galaxies sitting next to each each in the constellation Leo, they are M66 (top left), M67 (bottom left) and NGC3628 (right).

This is the first image using the new CGEM mount and the second image using the CLS CCD filter and it shows a few problems. Visually the first problem that I see is the colour balance, this is a direct effect of using the new filter which has shifted the colours way over into the blue and I’m having trouble working out a good method to correct it.

The second problem is the slight stretching of the stars along the RA axis, this is primarily a result of periodic error which I need to work on. I’ve gone back to using guidedog for guiding on this image as guidemaster was giving me a lot of issues, it still needs a bit of fine tuning. I also want to test out the guiding facilities in EQ Align to see how that deals with the mount.

Also as a direct result on the horrible street light over the garden the images all had an awful amount of gradient in across them, happily however Pixinsight was able to deal with that problem. I’ll have to remember to stick my big cardboard box over the light next time.

Tonight though I got this whilst imaging the Leo triplet :

It looks like a satellite flare but from which of the many hundreds of objects in orbit I couldn’t say.

All of this stirred up the requirement to build something more substantial, so I started hunting around for the hardest part to find, a short length of large diameter steel tube. I found various sites offering offcuts but the price was always way more than I was willing to pay and would have pushed the total cost up to that of buying a purpose built pier.

Eventually though I located a seller on ebay with a length of 6″ outside diameter stainless steel tube, however the wall thickness was only 2mm which was a bit of a concern.  I did some research however and came across this article from which I took the basic understanding that it is the diameter of the tube rather than the thickness of the tube that influences it’s stability. Provided the tube is strong enough to take the weight the thickness of the tube is not so relevant.

I also learnt a bit more about the dynamics of a telescope pier, understanding that it works like an upside down pendulum, so the base should be strengthened as much as possible to reduce movement.

With this knowledge in hand I bought a 1m length of the stainless tube for a very reasonable price, a half meter square piece of 10mm thick mild steel plate and a length of 20mm threaded rod which in hind site made things much harder and is a bit over kill. Though saying that now  every thing is in place they do provide a rock soild hold for the mounting plate.

To work then, and I wish I had remembered to take pictures of all this but it seems to be a habit that I forget :

• Cut the plate into four 250mm square sections for the top, bottom and mounting plates. The last piece can then be further cut up for gussets for the top and bottom plates. I used an angle grinder with a 1mm thick cutting disk, easy work.
• Drill the holes for the threaded rod to mount the mounting plate to the top plate. If the holes are big you will need a drill press or a good speed controlled clutched drill. The clutch is important as it keeps the drill from breaking your wrists when the bit catches. My hobby drill press was not up to the job, but Dad’s SDS drill had no problems.
• Weld the top and bottom plates on with the gusset pieces, again thanks to Dad for the welding skills.

And basically that’s it, I had a few issues with mounting the pier to the concrete, the old threaded rods that were sunk into the base were at weird angles and I couldn’t get the pier to drop down to the floor without drilling bigger holes in the base. Unfortunately by this point I was far away from the tools I needed to do that and all my blacksmith bits were blunt.

Instead I chopped off the old rods and drilled new holes for anchor bolts, they seem to do the job nicely though they can be a bit of a pain to get working.

The pier was painted with a coat of primer I had in the garage and a mix of blue car paints which ended up giving it a nice dark shade, all back together the finished article looks like this :

I’ll be testing it this evening with any luck, and I’ll try and take some video of the vibration after go-to and knocking the tube.

I’m contemplating having a theme designed for the site at some point, perhaps next year as a reward for keeping up with this! Let me know what you think of the new look via the comments.

I went to Astrofest with the plan of replacing my mount, I love many things about the sphinx and I’ve done well with it over the last year but unfortunately my load capacity requirements have reached the point that it is beyond the ability of the sphinx to cope with it. So I had to make a call on a new mount, the choice was between the EQ6 and the Celestron CGEM, the EQ6 had the advantage on  initial price, but would need upgrades to replace the saddle mount to a losmandy style which would bump it up to not far off the CGEM. It does however offer access to the excellent EQmod software suite.

The CGEM is at heart a modified EQ6 sporting  several useful upgrades to the budding astrophotographer, servo motors replace the stepper motors, the bearings are different, it comes with a long losmandy style saddle as standard and will track up to 20 degrees past the meridian for excellent uninterrupted imaging.

In the end I went with the CGEM based on the above reasons and some excellent reviews, I took it home after the show finished on the Saturday and spent the Sunday modifying my temporary pier to get it mounted, more on that later.

Once mounted the long wait for a clear night started, I managed to snatch a few hours here and there which gave me enough time to get the mount aligned and to learn how to use the goto properly and configure the many options. I’m loving having a mount that can park and hibernate, it saves so much time in setup.

Eventually the skies cleared for a full night which finally gave some proper time for testing. In all movements the mount is very positive, making no sign of being under strain when slewing. Once aligned using the two star alignment and a couple of additional calibration stars goto accuracy was excellent, putting each object central on the canon 1000d.

Periodic error however is much worse than seen on the Sphinx and will need properly training, my initial results using Celestron’s own PEC tool were disappointing. However I have read of very good results achieved with PEMpro and the CGEM, but unfortunately the software currently has a bug which stops it properly working with my SPC900NC webcam. If anyone knows of any other software for training PEC which can upload it’s results back to the mount please let me know, I seem to have no end of software which can analyse PE but none of them can push the results back.

Right now guiding is basically perfect in declination but I am getting elongated stars in RA, so PEC is a priority.

The pier is  problem, the CGEM is much heavier than the Sphinx and the amount of vibration and movement in my cobbled together multi-section pier is not acceptable. I have now managed to get hold of a length of 6″ outside diameter steel tube and some 10mm steel plate. I’ll be cutting this during the week and heading down to my parents on the weekend to get some helping welding it all together. Hopefully that will fix some of the unwanted movement in the mount and improve the guiding.

Over all though I’m happy with the CGEM, I’ll update with some pictures and PEC results once I have them, though the weather continues to look miserable for a while to come.

On the first night I used the excellent EQAlign to get my polar alignment as close as possible. The guiding after this was massively improved in declination with very few corrections required, probably the best dec guiding I’ve seen from the sphinx. The RA however was all over the place with very rapid oscillations that the guiding had problems with.

Second night, I spent a lot of time getting the balance of the mount as accurate as possible, had another go with EQAlign to tweak that side then tried again. The result? Excellent RA guiding, but now the declination is a mess showing a slow oscillation as it seems to drift first one way then the other. The horrible declination backlash of the sphinx made this very difficult to manage and adjusting the movement speed or aggression settings only sped up or reduced the oscillation period.

I really like the sphinx, I’ve had a great time with it and learnt a lot, but I think the time is coming for it to be replaced. It is overloaded these days, and the performance of the mount suffers because of this.

Anyway, before heading to bed on Saturday night I took a stack of 100 images of the full moon through the 250mm reflector.

• Orion Optics 250mm F4.7 Reflector
• Vixen Sphinx SX Mount
• Baader MPCC
• Astronomik CLS CCD Filter
• Canon EOS 1000D
• 24 x 5 Minute exposures at iso800

Guiding Setup

• Vixen A70LF refractor with 0.6x Focal Reducer
• Modified SPC900NC
• Guidemaster auto guiding software

A slightly different processing from a stack with different options :

Imaging Setup

• Orion Optics 250mm F4.7 Reflector
• Vixen Sphinx SX Mount
• Canon EOS 1000D unmodified
• Astronomik CLS-CCD Filter

Guiding

• Vixen A70LF F12 Refractor
• Modified Phillips SPC900NC webcam
• 0.6x Focal Reducer
• Guidemaster

Images

• 11 x 3 minutes @ ISO800
• Darks and Flats x 15 each
• Aligned and Stacked in Deep Sky Stacker
• Processed in Pixinsight

However if for some reason you were linking to an update in the old format then your link is going to fail. Hopefully you’ll follow the link on the error page and find your way here instead.

Update!

The site changes have been live for a bit and I’m seeing a bunch of errors for misdirected links from google, and apparently I’m getting traffic coming in from a link on the overclockers.co.uk forums which I’ve now broken, so sorry about that if you are visiting from there.

Everything should returns to normal over the next few days as the search engine bots update and at least now the last year of updates is available again!