Gemini PAC bug

[Lee]

This topic might be getting a bit old.... but .....

I have worked out that my Gemini (and maybe all of this version) has a definite PAC bug (polar axis correction). It issues elevation corrections the wrong way. Azimuth seems fine - elevation is definitely reversed.

Here's what I did.

Built a model (5 stars each side meridian, all separated by at least 2hr RA).
A=-7, E=7

Did a PAC on SAO128085 (nearest star to intersection of meridian/equator) - adjusted so as to only correct the error by about half.

Built same model again-
A=-3, E=13 :shrug: A has improved, E not so.....

I did PAC on the same star - but this time, did not touch azimuth knob, and pushed the star further away from the centre with the elevation knob, instead of correcting it.....

Built same model -
A=-3, E=4 - what the?

Did another elevation-in-reverse PAC, but did make some azimuth adjustment in the correct direction....

Built same model -
A=-2, E=3

Same again.....
A=-1, E=-1 :D

I think Gemini is up to Level 4, V1.04 nor - this unit is a V1.01.... If anyone else would try it, that might be cool..... if PAC worked well, I think it would be a huge time saver for people especially with non-permanent setups....

[Lee]

Further-
I've contacted Rene Goerlich (Gemini's creator) - he is sending me a different eprom to try.... apparently he has asked lots of southern users about PAC, but has never received a detailed reply - I think we all just give up and drift align!

[rogerg]

Agreed - we all give up and drift align :)

I tried it on Saturday night, just for the hell of it, see if it'd work before I started my drit alignment.

I found that it asked for a large altitude correction and a small azmith correction when I was expecting the opposite. I made the correction but then found during drift aligning I took back a large amount of the altitude correction made, and made further azmith change. It might have been all of, or more than, the altitude correction that I made in reverse doing the drift alignment.

Seems maybe it does the azmith the wrong way around maybe.

I'm using level 4, but not sure exactly which version right now, and it's 38 in my observatory right now so I'll check later for you :)

Roger.

[Lee]

I really want this to work.... I can drift align, but its often difficult to get a decent bright star really low down, unless Orion happens to be rising when I am drifting!

[Bassnut]

Ive had this sort of reversed effect useing pempro on the G11, couldnt work out if it was Gemini or Pempro, Pempro swore is wasnt their fault, but now (for some time) there is a sthrn hemi check box on their app. I gave up anyway, just drift align.

[Lee]

I aligned mine doing the reverse of what the mount suggested - something is wrong....