Very Amateur Astronomy

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I took a look at the Vixen site to check the firmware version installed on the Star Book and found it a very long way out of date.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.