Very Amateur Astronomy

I never really liked the somewhat over bearing astronomy / horse head theme I’ve had on the site for the last (nearly) a year, I always found it a little hard to read but could never find anything better. However hunting around I ran into this new theme today and I’m quite happy with it, it’s a free design by Sameh Khalil. So my thanks go out to him for designing an space based theme which doesn’t go to far over the top.

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.

The blog has been looking a bit bare this month, though with Astrofest and a somewhat dented credit card I do have something to talk about despite the terrible weather.

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.

Well August was a quiet month, mostly due to a lack of clear skies in the first half of the month and being on holiday for the second half. We spent two weeks camping in the Italian lakes, but don’t worry, I went armed with scope and camera so there will be some updates soon reviewing the scope and showing off the new image.

The weather for June has been pretty much shocking so far, opportunity’s for any observing or imaging are few and far between and the weather is unlikely to improve for another week or so. All the more annoying as my little Philips SPC900NC webcam arrived!

Basically since our good friends Sarah and Mike headed off to New Zealand my wife has been badgering me to pick up a webcam for some audio / visual gossiping. However as I’m getting a camera I may as well get one that’s useful for astronomy purposes as well. The SPC900NC is much loved for this but unfortunately very difficult to find any more. I managed to pick up a second hand one from amazon and got a cheap adapter. The lens is simple to remove (pry off the shroud, unscrew the lens) and the adapter screws back in it’s place.

The plan for the webcam is two fold, first use is for imaging planets and the moon. The second is to try it for autoguiding for long exposure deep sky images. I’ll report more on both of these once I’ve had a chance to try it out.

I’ve been getting my tools out for some astro DIY over the last week. I ordered a slab of 10mm x 100mm x 400mm aluminium for a mounting plate. I had it all setup but right now it’s a little on the heavy side at over 1kg and my mount is already heading a little to close to it’s limit for my liking. This weekend I will shorten it, shape it and drill out some holes to lighten it which should solve that problem. the difference when it was mounted to the rigidity was very noticeable.

For auto guiding I need to piggy back mount my Vixen A70LF refractor onto the mount either attached to, or alongside the reflector. I have the piggyback scope rings and they mount fine onto the reflectors rings but unfortunately once everything is in place it pushes the centre of gravity of the scopes way to far out from the RA axis of the mount. This means that the single counter weight I like to use can no longer counter the pull of the telescopes even at maximum extension. I also don’t like the extra strain it puts on the two screws holding the scope rings to the dovetail bar.

The plan is to add some mounting holes to the reflectors tube rings further round to allow the refractor to mount inboard of the reflector, this will hopefully bring the centre of gravity of the scopes closer to the RA axis. I will also look at possibly mounting the tube rings directly to the mounting plate. Either way I need to bring the tubes closer to the pivot point in order that the mount may be balanced without adding to much counter weight.

Last night whilst working all this out I also made a few more adjustments to the mount, I think there still be a bit to much backlash in the RA axis but it at least moves well now as does the declination. The sphinx however remains a pig to balance, I’ve now taken to balancing roughly using the standard method then using the pitch of the motor when slewing to get it precise, once the sound is the same moving in both directions I know it’s happy.

I have read of people connecting multi meters to the motors to read off the power draw but I think that may be a project for another day.