Home Position.........

[ultramol]

After polar aligning my mount to put polaris in the little circle at the correct hour angle what should I see when looking through the telescope which is perfectly weights down and scope  up in the so called home position. Should I see polaris centred in my eyepiece, should I see the edge of the circle containing polaris kissing the centre of my eyepiece or should I see what would be the circle in my polarscope centred in my eyepiece. I ask this because when you look at the circle on carte de ciel that represents the home position it seems just to be off centre of polaris..Hope this makes sense !! Thanks in advance...Geoff

[Garethr]

Good question Ultramol,

In my scope at the home position I get nothing even when polar aligned to the nth degree.

I think it's as you see on cartes du ceil just off Polaris which makes sense as Polaris is not exactly 00 dec and 24 RA

Somewhere nearer 89 and 02

Gareth.

[Gazabone]

You don't need to worry about the main scope, the only thing you're aligning with the polar scope is the mount itself. Once you've got to the stage you've described by putting Polaris in the little circle, your polar alignment is sorted. The purpose of polar alignment is that the rotation of your RA axis is exactly in line with the Earth's axis of rotation and that's all.

Basically, once you've polar aligned, you can forget it and get on enjoying your main scope. If you're using a go to mount and you complete its alignment procedure (for which you do use your main scope) then the precise polar alignment you're doing isn't strictly necessary.

In any case, happy viewing

[Gazabone]

Ps most people's experience seems to be that getting Polaris in your main scope is very challenging from an Eq mount.

[ultramol]

Thanks for your replies. I was just thinking though if your polarscope is perfectly aligned then surely you should see a mirror image of it through your eyepiece. This would help in knowing if everything is as it should be...

[Lonestar70]

What you see through your OTA eyepiece in the home position will be determined, to a large degree, by the field of view of your scope/eyepiece combination, the accuracy of your home position and if you have any cone error... you may, or more likely, won't see polaris.

You certainly won't see anything remotely like the view through the polarscope since there is no optical connection between it and the main scope... and you won't see any sign of a polar circle... this is actually etched onto a graticule within the polarscope as an aid to alignment.

The home position is meant as a starting reference point for the GOTO electronics it has no real world, or space, meaning.

After polar aligning your mount put your main OTA/MOUNT back to the home position and then do a 2 or 3 star GOTO alignment... this should be more than adequate for visual use.

Good luck and clear skies.

Sandy.

[ultramol]

Thanks for that. I realise there would be no circle showing but it just intrigued me as to what you should see everything being accurately done. The reason I ask is if you send your scope to polaris the eq mount is in a far different set up than when in the home position to get to centre polaris..Once again thank you for your replies...Regards...Geoff

[ronin]

The polar scope is not pointed at Polaris, you do not put Polaris in the centre.

And as mentioned where the mount points and the scope points is independant, otherwise all you could ever observe is the northern axis point of the earths rotation, and there is nothing there, Polaris is just over a degree off of this position so that wil not be in view usually.

The EQ mount is Polar aligned by offsetting Polaris by the required amount in the polar scope, you however can point the scope what is in effect due South and observe Saturn, or due West and observe Acrturus and none of these scope movements alter the polar alignment.

If you do not have a goto then where the scope points and what you see in it after polar alignment of the mount is 100% irrelevant. You could store the mount such that the clamp the scope goes on is at right angles to the mount axis so after polar aligning the mount the next time you attach the scope and it is pointing East or West.

[brantuk]

If you are looking at the pole star in the scope - which I think is what you're getting at - you will see it's actually a double star. But as mentioned above, polar alignment of the mount is independent of this.