Handset polar alignment

[jambouk]

When using the skywatcher handset polar alignment routine, does it make a difference which two stars one picks, as with drift aligning? What would be the optimum difference between the two stars in RA and dec?

Thanks

James

[Owmuchonomy]

Hi James, in my experience yes it does. If you are setting up to image then

1) choose 2 stars on the same side of the meridian as your target

2) choose the 2 stars preferably separated in Dec by 10 deg to 30 deg and preferably separated in RA by 3 to 9 hours

I have a small notebook handy in the back of which I list by season the stars of choice and by East vs West. For example in Spring if imaging to the West of the meridian I choose two of the following Regulus, Capella, Castor or Pollux. If I image to the East I choose from Thuban, Arcturus, Spica and Vega.

[ronin]

Strange idea that somewhere it suggests one over towards the horizon and one close to the meridian.

[jambouk]

Does cone error reduce the accuracy of polar alignment when using the handset method?

James

[Zakalwe]

Does cone error reduce the accuracy of polar alignment when using the handset method?

James

You can choose a 2 or 3 star alignment model before polar aligning. I assume that if you choose the 3-star then cone-error is calculated for?

[jambouk]

That may be the theory, but i've found that doing a handset polar alignment after a three star alignment results in worse polar alignment that just guessing where the north celestial pole is!

I just wondered if cone error resulted in poorer handset polar alignment after a two star alignment than if there was no cone error, or if cone error has no impact on the handset polar alignment routine.

James

[jambouk]

Interestingly, I've just seen this:

"In addition, there is also a software-assisted Polar Alignment routine requiring the alignment of at least two test stars (but preferably three to obviate cone errors) followed by the selection of a further test star. This last star is selected after choosing ‘Polar Re- Align’ from the handcontroller’s menu options and then centring it in the eyepiece. Once centred using the direction keys, the routine moves the telescope to an offset position and you then re-centre it manually using the altitude and azimuth adjustment bolts. This process uses a complex algorithm to correct any polar misalignment detected in the star’s position."

From: http://www.firstlightoptics.com/blog/skywatcher-az-eq6-gt-review-part-1.html

But I still find my polar alignment using the handset is awful after a 3 star alignment, and pretty good after a two star.

James

[knobby]

Interesting as the AVX mount suggests 2 star + a few calibration stars in its aspa align routine

[Baffa]

I do the same here, 2 stars and then polar re-align. I tried 3 stars but it doesn't seem to work correctly and I assume there is some kind of bug in the software.