Refining polar alignment with Mel and Maz errors (Skywatcher)

[jambouk]

I tried to refine my polar alignment last night using the Mel and Maz errors that the latest version of the firmware on the Skywatcher handset now offers. I didn't manage it (largely because my initial polar alignment was awful for various reasons).

When it asked me to re-centre the reference star using elevation, turning the altitude knob didn't actually bring the reference star through the centre of the FOV, just closer to it but not on a path which would go through the centre of the FOV; to get the reference star in the exact centre of the FOV I would have had to tweak both the altitude and azimuth knobs when trying to correct just the "Mel" error.

Is this normal? Does the mount need to be fully level get this to work?

Thanks.

James

[Tinker1947]

I found doing a couple of PA's with a single star alignment in between sorts the problem....

[themos]

My guess is that if you are sure that your Azimuth/Elevation adjustments are in the horizontal/vertical planes (because you have a spirit level, say), then follow the instruction and only move the adjustment mentioned in the instructions. If you are not sure, then do both adjustments and get that star centered!

[jambouk]

Themos, I didn't level the mount last night, well not with a spirit level, and the more i think about it, there more i think that could be one of the places i went wrong. I have a spirit level with me, so will give that a go tonight if the cloud permits.

Tinker, is this what you mean? Polar scope PA; 1 star alignment; handset PA; 1 star alignment; handset PA; 1 star alignment? The instructions are quite specific in saying that the handset PA can only be done after a 2 or 3 star alignment.

Thanks both,

James

[Tinker1947]

Themos, I didn't level the mount last night, well not with a spirit level, and the more i think about it, there more i think that could be one of the places i went wrong. I have a spirit level with me, so will give that a go tonight if the cloud permits.

Tinker, is this what you mean? Polar scope PA; 1 star alignment; handset PA; 1 star alignment; handset PA; 1 star alignment? The instructions are quite specific in saying that the handset PA can only be done after a 2 or 3 star alignment.

Thanks both,

James

Yes, i do a 2 star then a PA, then a 1 Star then a PA, then a last 1 Star as mines doesn't allow GoTo a star straight after a PA......

[jambouk]

OK. Now the mount is level, I will try the instruction book way first, then I'll have a go at your method if that fails. Though having re-aligned my polar scope reticle today (not perfect but much better than it was), I am hopeful a conventional polar scope PA will be reasonable.

James

[jambouk]

Well i did an ok polar alignment with the polar scope, then a two star alignment (as there were only two stars i knew visible) and it said my mel and maz errors were 5 arc minutes and 3 arc minutes respectively so i thought that was good enough for playing around. Then out of curiosity i did a three star alignment, and one of the errors jumped to something like 1 degree, 58 arc minutes out! I experimented with tracking to see how good it would be, and got to 3 minutes ok, but then rain set in, and it has been raining on and off since, and i got bored of waiting and was worried something crucial was going to get damp so during a lull in the rain i packed up.

Maybe try again tomorrow night; i've left my mount out (under covers) so hopefully my set up time will be less and i'll have more time to play tomorrow!

James