Cracked it !!!

[Mike]

YAHOOOOOO!!!!!

I finally cracked polar alignment. After trying out all kinds of methods and spending 3 entire sessions devoted to alignment, I did it tonight.

Using the "Kochab's Clock" method, I have can now do 3 minutes unguided single frame exposures!

It is a dead simple procedure as long as your polar reticule shows a scale for minutes or like the EQ6 one has the offset from the NCP to Polaris marked. Took about 10 minutes.

Here is a link to the method - http://www.weasner.com/etx/ref_guides/polar_align.html

[JohnP]

Now wouldn't that be a great name for a webpage.....

Congrats on polar alignment - I'll give it a try myself... I think the reticle on the LXD75 is suitable.

Cheers,  John.

[Mike]

Ok here is a single 3 minute raw frame from tonight......



...and here is a 4 minute raw frame of M51 area. A slight distortion in the stars is just starting to become visible. The clouds rolled in shortly after this shot so I packed up and went inside.



Anyway, this is a huge improvement on my 30 seconds and I am sure once the technique has been refined I will get even longer. With guiding I am aiming for 10 minute raws.

The next thing I have to contend with is Periodic Error so will try out the mounts training routine next time, then onto the technicalities of guiding itself.

[Rocket Pooch]

hi mike,

i thought you we're doing that anyway which is why i could not understand why you were unable to do the 3 minute exposure i was using the same mount?  does your finder scope have the offset ring in the field of view where you lacate polaris (set between cassiopia and the plough with koncab marked on it) and which sets ncp is near enough the right position?  mine does and this give you the right ncp within +- 5 arc seconds (i think).

but drift alignment is the next thing i suppose then guiding.  by the way on the starlight express site some chap put a posting up where he had autoguided a eq6 for 20 minute subs using the sxv camera, he lives in an urban location and said that even with an astronomik ha it whited out after 5 mins anyway, so i suppose 5 mins will be the max for us

see ya soon

chris

[Mike]

There is a guy called Synner on the UK Astro site that has an SXV-H9 and he often does 20 and 30 minute subs.

I have the same polar scope, but Kocab isn't on it. Kobac is a long way from Polaris and wouldn't fit inside a polar scope without it being extreme wide field.

[Rocket Pooch]

Yup its not, but if the polar scope is rotated to match cassiopia and the plough then the little cross points off in the direction of konchab i.e. of the tal of the plough towards alkaid and bingo put polaris into the little circle and you're nearly there.

What was you doing before, was you putting polarin on the cross?

[Mike]

No I was putting it in the circle,  but it still wasn't giving good tracking.

[JohnP]

Mike,

I use a great little prog written by Jason Dale - it's free & you can download it here:

http://www.visionexperts.co.uk/polarfinder/

Basically, it shows you exactly where NCP & Polaris is for any given time - normally it plots 4 graphs based on your system clock (but you can change this).

All I then do is look through my polar alignment scope & rotate the RA axis until the reticule pattern looks the same - I then just align Polaris onto the round circle & bingo.....

This seems to give very good alignment.

Cheers,  John

[Mike]

Yes I have that program and have tried it. It is OK for visual but I haven't managed to get it good enough for imaging.

[Oscar the Cat]

Nice one mate, Looking forward to see the images