Tonight I shall be mostly....

[Psychobilly]

Trying to improve my polar alignment...

Now the obs is more secure and the scopes can be left in situ... its time to tweak the polar alignment...

I hadn't bothered whilst the scope was being setup and taken down for every session instead choosing to let the auto guiding take care of things...

So today I Marked the existing alignment with a saw cut across the "join" then "separated" the two plated that allow Azm adjustment as they had been "painted" together cleaned the surface between them and oiled the surface so that they no slide over each other...

I have set it back to the original marks and will go through the CPC's built in wedge align a few times to see if I can get the alignment a bit better...

I'll use shims for Alt adjustment...

The pier design doesn't really allow for easy drift alignment so I'll have to make the best of it...

Hopefully I can get this done within the first hour or so so I can get a bit of imaging done... If I can remember how to do it

Peter...

[Helen]

Sounds good Peter, hope it goes smoothly. Its worth the effort of spending time getting the alignment spot on when you only have to do it once

I'm having an experimentation evening too - hyperstar and new camera. Maybe two new bits of kit together is asking for trouble!

I can't believe the forecast... I might actually get to learn and then consolidate - unheard of!

Helen <off to download the QHY drivers>

[Psychobilly]

Hope you have a good un Helen ... I'd much rather be playing with new toys like those

I grab a few hours "Ugly" this afternoon to try and make it through the night...

Peter...

[George]

Ive been doing the same on and off the last couple weeks, skies have been lousy for imaging so like you Ive been improving polar alignment and playing with eqalign.

[GazOC]

The sky is looking great (fingers crossed) and I havn't been out for ages so I won't be messing about with any complicated gear, the big Dob is getted planted on the lawn and I'm going to have a good, long session with that tonight.

[Psychobilly]

I was usign the pier as a work platform during the obs dome mods so I decided it might be worth checkign the alignment

I have just "centered" my 12mm illuminated reticule EP so will use that initally on its own and then with a 3X Supreme Barlow for the "tweaks".

Hopefully that will be good enough...

Peter

[ncjunk]

Good luck to you all, hopefully we will see the results posted!

NC

[Psychobilly]

Cheers Neil

I haven't imaged anything deep sky for ages ....

Hoping to get a few hours on the VSC area but no dobt i'll be drawn to Cygnus as soon as its in view instead - I just cant resist those glorious nebs....

Peter

[Jarndyce]

How are you checking the accuracy, Peter?

Drift alignment? I've read about this, but never tried it.

[Psychobilly]

My DIY pier isnt the easiest thing to accurately align so I dont bother with drift alignment. Trying to nudge 50kg's of scopes and steel isnt the easiest thing to do.. I should have designed in a thread driven adjustment... but it was a KISS design

So I am making do with the CPC's built in wedge align function and usign a 12mm reticule EP which I have "centered". The wedge align routine works by initially doing an EQ align then the mount slews and you center polaris in the FOV by adjusting the mount in Azm and Alt - you then have to re-align... again I repeated that a few times to check the consistency.

I then took an 8 minute unguided and 8 minute guided image of Regulus to check for any trailing

The guide graphs look a lot better and there are much smaller corrections being made so I'll probably leave well alone for a while again now

The images form tonight look fine

Peter...

I'll post some guide test shots later today...

[Jarndyce]

Sounds good, Peter. Thanks for the explanation.

With a guided scope, how crucial is the polar alignment? I suppose if it's spot-on, only the RA motor would be utilised, which would make it smoother?

[Psychobilly]

That sounds about right... The mount was certainly making a lot fewer and smaller corrections lastnight and I havent had to throw away any subs..

I'm just stacking the data from lastnight then i'll get round to pulling the guide test images and guider output graphs from PHD..

Imaging Scope - William Optic Megrez72 FF III - Modded Canon 1000D - Baader ACF

Main Scope/Mount - Celestron CPC800 on DIY Pier and Wedge

Guide Scope - 500m f8 M42 T Mount Lens with Meade DSI IIC

8 minutes Unguided

[ATTACH]21249[/ATTACH]

8 Minutes Guided

[ATTACH]21250[/ATTACH]

And the guide graph from PHD....

[ATTACH]21252[/ATTACH]

Peter....

[Reggie]

That osc index doesn't look too hot, your guided/unguided images tell a different story but according to the phd manual at least:

In the lower-left of the graph, an "oscilliation index" is shown. This is the result of calculating (in the current window's worth of data), the odds that the current RA move is in the opposite direction as the last RA move. If you are too aggressive in your guiding and over-shooting the mark each time, this number will head towards 1.0. If you were perfect and not over- or under-shooting and your mount had no periodic error, the score would be 0.5. Perfect with periodic error and the score may be closer to 0.3. If this score gets very low (e.g., 0.1), you may want to increase the RA aggressiveness (and/or decrease the hysteresis). If it gets quite high (e.g., 0.8), you may want to decrease the RA aggressiveness (and/or increase the hysteresis).

[Psychobilly]

I reset the PHD setting for RA Aggressiveness and RA Hysteresis back to their default values and got scores of between 0.4 and 0.5 all night... forgot to take the graphs and log data of the lappy though before closing up the obs... I'll grab them tonight..

[ATTACH]21322[/ATTACH]

Was it any better...

I can't really say as the skies became quite moist last night and transparency suffered as a result which was a bit of a gutter as I had left the scope running all night on 2 targets - the FWHM values crept up all

night

Peter....