EQ6 Polar alignment

[keithmrris]

Hi hope someone can help me. I used to use a Meade LXD75 mount and found it a doddle to polar align, however I am having difficulties getting the EQ6 Pro as accurately aligned.

The polar scope is collimated to the mount PERFECTLY. Where I think the error is in, is the small circle into which you put Polaris is SO big compared the the Meades reticule.

Where abouts in the small circle should Polaris be positioned, it isn't dead centre. You could fit Polaris around 20 times over in this circle it is so big.

Should I be aiming for the top part (or inner part towards the centre of the reticule) or the bottom part?

Any advice appreciated

Keith

[iwatkins]

Hi Keith.

You should see a small circle on the outside of the small circle in the centre. Put Polaris here. See image below.

Cheers

Ian

[keithmrris]

Hi Ian, yes I know that, but the small circle will hold Polaris 30 times over, it is huge compared to Polaris. Where abouts in the smaller circle, towards the top or bottom?

I find I am getting unacceptable star trailing after 3 minutes. With my old LXD75 mount I could expose for over 7 minutes before trailing became noticeable.

Keith

Keith

[RogerTheDodger]

Have a read of Great Bear's explanation of how to polar align http://stargazerslounge.com/beginners-help-advice/103827-polaris-transit.html#post1432597

[cgarry]

You are right Keith, the circle is far too big. You need to try and get it as close to the centre as possible.

Cheers,

Chris

[keithmrris]

Thanks Chris, that's the sort of answer I was looking for. That is in fact what I have done so the only other thing that could be causing my problem is the mount might not be dead level, I will have to check that but I thought I had when I installed the pier.

Keith

[keithmrris]

Oh and before anyone starts to go on about drift aligning, not possible with my scope in its current location can't see enough sky from the NE round to the SSE.

Had already thought of that even to the limit of buying a 12.5mm illuminated drift alignment eyepiece.

Keith

[Psychobilly]

Being Level is not that important important for a GEM only the PA...

Being level will improve the "goto" accuracy of the initial alignment stars and make drift aligning a little bit easier as it will de-couple the alt and az adjustments.. . to help you check if polaris is centered rotate the mount in RA and Polaris should stay on the larger circle...

Billy...

[MikeP]

If you link your EQ6 to computer, have a look at Alignmaster Keith. I've got similar view restrictions and it works for me.

It offers you a number of pairs of stars (with a simple display indicating where they are for the terminally forgetful - such as I). You pick a pair, slew to the first star, centre and "confirm". Then slew to the second, centre and confirm again.

The software can then calculate your alignment error. In the next step, Alignmaster slews away from the second star and you recentre using the altitude bolts and confirm. It then slews away again and this time you recentre using the azimuth bolts.

Depending on how far out I was to start with, I use the procedure two or three times - it is very quick. It is a good idea to use a low power eyepiece for the first iteration in case the slews away from the star take it outside your FOV.

Mike

[NickK]

Have a read of Great Bear's explanation of how to polar align http://stargazerslounge.com/beginners-help-advice/103827-polaris-transit.html#post1432597

nd then rotate the entire Polar Scope (normally by rotating the telescope's entire RA Axis) such that today's date (on the Date Ring) aligns with today's current time (on the RA Ring -

This doesn't make sense.

Both the RA and date rings rotate at the same rate (they're attached to the same axis) thus it's impossible to align today's time with today's date.

Think there's something missing here.

[RogerTheDodger]

This bit should also be done before that.

In everyday use then, with the mount set-up, just start by locking the RA Ring so 0:00 (midnight) is at the top

Just work through it, it really does work... you can set polarfinder to any date/time and then compare it it on the polarscope - works every time.

[Starblazer]

On the EQ6 the date/time setting circles are NOT fixed and can be adjusted to be used to aid in polar alignment and for setting home positions to reduce the need to keep aligning, providing you always view from the same place

[NickK]

Nope still doesn't make sense I know the date disc can move but it doesn't say anything about rotating it.

So do you move the RA (time) setting circle so that the current time matches the angle of date? But that does't alter the RA so doesn't change any polar alignment values.

The rotational vectors for drift alignment and the calculation back to identifying the alt-az movement with FOV scaling makes more sense!

1. You set the current longitude on the date circle against the index line.

2. Then rotate RA so that the RA pointer points to today's date on the circle.

3. ? So what next?

I can get set theory, fluid dynamics but this doesn't make sense - I suppose I'll have to side down and work out all the steps from first principles :/

[RogerTheDodger]

short version...

1)look through scope, rotate RA to put the small polaris circle at the bottom, lock RA. Lock RA ring in 0 position.

2)rotate date ring so Nov 1st is at the top, and set the white index mark to 0 and lock the ring.

3)don't worry about Meridian Offset for now, unlock RA clamp and rotate RA axis to set todays date on the date ring against the time now (using UTC...) on the RA, lock RA clamp.

4)look through polarscope and use alt/az adjustments to put Polaris in the small circle.

You can try that indoors and compare it to the output of polarfinder - the small circle should be in the same place that polarfinder says Polaris is.

[NickK]

3)don't worry about Meridian Offset for now, unlock RA clamp and rotate RA axis to set todays date on the date ring against the time now (using UTC...) on the RA, lock RA clamp.

I get it all already.. however there's a gap in the communication here.

Imagine the RA as a tube, if both date ring (not moved) and time setting circle (not moved) are locked to the tube then moving the RA to today's date is fine, however there's no way to move RA to the time as it's locked against the RA too.. thus you have the time or the date but not both.

I hope you can see where I'm going wrong in this chain of thought..

[RogerTheDodger]

ah, with you now. With the RA ring locked at zero, when you rotate the scope in the RA axis the RA ring shouldn't move, but the date ring should.