Very Amateur Astronomy

I seem to have had some issues with the permalink structure which I had not noticed. Apparently any of my updates not on the front page had vanished and were returning a page not found error. I have reset the site back to standard permalinks now and the archives have sprung back to life.

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!

I had a go with getting autoguiding working the other night with some success and some issues. The first problem was that my wireless access point down the shed wasn’t communicating back to the house very well resulting in dropped packets and the starbook being unable to get an IP via DHCP. In the end I directly connected it to the laptop via a crossover cable. That worked but it’s not quite what I was after.

Next I slewed my now dual mounted scopes round to Arcturus and spent some some getting the secondary scope lined up on it. I need to get my old spare red dot sight mounted to it to make things quicker. Once there I hooked up the webcam and ran through the configuration for PHD Guiding having a play with the webcams gain and exposure settings at the same time. It was a quick and easy process without errors and looks like it will work OK.

Next I spent some time on alignment, trying out the CCD drift align method. This was new to me and quickly showed that the mount was out, pointing to far west. I was short on time so didn’t spend to much time on this. I’ll have another go when the weather allows.

The last thing I tried before calling it a night was to test the sensitivity of the webcam for a guide camera. I slewed the mount up to the ring nebula and then tried to locate a suitably bright guide star in the second scope. There was not quite enough movement to reach Vega and the standard webcam was incapable of picking up anything else in that region. So we can say that a standard Philips SPC900NC webcam is not suitable as a guide cam for astrophotography.

Last night however I took a trip to Maplin and then took my soldering iron to the webcam. I’ll write about the result soon.

This is not the month for astronomy, why the weather men ever put anything up that isn’t ‘It’s April, what do you want?’ is beyond me. I’ve not done any new imaging or observing as when I have expected clear skies the clouds have rolled in the minute I get the shed roof off, or I’ve been convinced to get settled in in front of the TV with my wife and a glass of wine and it’s turned into a crystal clear night.

I have however not been entirely idle. I’m currently constructing a light box for the scope, it’s going reasonably well but I ran out of glue for the hot glue gun last night so it’s on hold for now. I’m following a selection of plans available on the net and the idea is that it will just slot in over the top of the scope.

I should have it finished for the weekend so we’ll see how well it performs then.

I’ve been looking a bit more into image processing and I cannot believe how blue my colour image is, really, my eyes must have been tired as I didn’t spot that at all. I need to go back to that and start again, being a little more careful to achieve a proper back ground black level. I know I’ve got a great amount of detail in that image but pulling it out is the real challenge.

I’m hoping the skies will clear for the weekend as it’s the first in a long time where I have nothing else I should be doing, but well, it’s April.

It looks like the issues last night were caused by the RA motor pushing itself away from the RA drive shaft. The motor and shaft run parallel and are connected by a pair of gears wheels. The RA motor is held in place against it’s mounting plate by four screws but there is a small amount of play to allow the two gears to be properly meshed.

It seems these screws were to loose and possibly the RA axis was to tight which has allowed the torque of the motor to push itself away from the RA shaft. A real pain to be honest which would explain the dotting effect seen in the second picture below where the gear wheels are not in contact all the time so you end up with dots where it’s tracking and a dash where it’s not.

This morning I have removed the RA motor and re-adjusted the the RA shaft worm mesh, I’ve reduced backlash on the mesh and it now turns by hand. It still feels a little tight so maybe I need to dismantle it and replace the greece at some point. I’ve replaced the screws holding the RA motor in place and hopefully have the gears meshed a little better now. 

The MET office tells me it should be clear tonight, so we shall find out then if my work have made the required difference.

Not much to report recently, I’m still getting used to the new mount.

BAS have been running a moon watch in a local shopping centre so I’ve been along there the last couple of nights with the scope giving the public a chance to take a look. It’s been a lot of fun and we’ve had all sorts coming through to take look. This being the international year of astronomy you should be able to find similar events in your local area.

I picked up the Vixen Sphinx mount on Saturday morning, but didn’t get round to having a play with it until last night due to having to go down to Eastbourne for the weekend. 

I set it up in the front room so I could have a play and had a look at putting my polar scope on it. Unfurtunately the Sphinx series has gone away from the standard fittings pioneered by themselves. So I’m going to have to keep an eye out for a spare Vixen Polar scope, or just do without and drift align instead.

Once I had it powered up I took a look at the Vixen site to check the firmware version installed on the Star Book and found it a very long way out of date. Updating is a breeze, the Star Book has an ethernet port so you can just hook it up directly to a laptop or even a router, it’ll pick up an address off DHCP.  Run the update application to update it, or connect to it via HTTP to fill in comet / object data if required and your good to go.

Once that was done I took a look at the go-to funtions, nothing much to say on that front yet. It’s a new experience to me having a computerised goto so I’m still developing expectations. I’ll say this though, it’s just so cool having the scope swinging round in the shed at the touch of a button!

I had a few issues with alignment, without the polar scope it’s tricky to get it close and attempting to drift align didn’t work at all. I think I need a rethink on that front, I’ll have to align it with the scope locked in a north pointing position and use the telrad. Hopefully that will get it close enough, once I’ve had a go I’ll write some more about it. I can’t help thinking that it’s doing something odd with it’s RA tracking, mostly as the scope view on the Star Book doesn’t seem to move at all, though I can watch the  scope itself physically move in RA as time goes on. I was expecting the scope view in the star book to precisely track the motion of the scope in RA, whike chart view allows free scrolling around the sky view on the display. It’s a bit confusing but hopefuly someone on the Yahoo sphinx user group will be able to fill me in.

More when I’ve had further time to play

Pretty much everything I wrote below is null and void.

Vixen Sphinx SX, second hand, I’m going to get it early tomorrow.

After waiting months, spending a night lurking in a vault under Geneva earning overtime and coming to the difficult decision to sell some of my other toys that no longer see much usage I can finally afford a new mount. Now comes the really hard part though, what do I get?

The budget is under £1000, the mount needs to carry my 250mm Orion Optics reflector and the 70mm Vixen guide scope and anything else I have hanging off it. The obvious answer then is the Skywatcher EQ6 synscan or syntrek. It will easily carry the load, can be controlled from the laptop, it comes highly recommended, easy choice.

Not quite.

Some considerations need to be looked in to. My pier for instance has a leveling plate and bracket to fit the head off an old EQ5 tripod, thereby allowing me to mount the current horrible old EQ4 mount directly on to it. The EQ6 doesn’t have the same tripod top and I don’t think the bolt holes for the legs will match the bracket on the pier. That means I have to go see my dad and ask him to make me another pier head bracket to replace the one he made me not a month ago.

Secondly I have to use a pier extension to raise the height of the mount to get decent skies, which means I’ll need a new one as my EQ5 half pillar again won’t fit the EQ6.

Trouble and strife.

The easy option is to just get an HEQ5 instead, which will slot right in to the existing pier without any mucking about or need for new parts.  Also it costs a lot less and I can then afford to get the guide camera I want as well.

The problem is one of capacity. The rule of thumb is’ over-mount, under-telescope’. Or to put it another way, your payload should be no more than two thirds of your mounts capacity. So lets do the figures.

Orion Optics Europe 250mm OTA – 10kg (say 11kg due to telrad / crayford focuser)

Vixen A70LF Refractor – 2kg

Canon EOS 1000d – 0.5kg

13.5kg total

Counterweights are 5kg each and lets say for arguements sake I use a long shaft and only need one, that still brings the wieght up to 18.5kg, or more than the maximum stated capacity of the HEQ5. The EQ6 on the other hand still has another 7kg to spare.

Decision made I guess.

I’d better call my Dad and get him to warm up the welder.

Nothing to see here yet, I’ll get some content up soon.