Problem with PAC in Southern Hemisphere

[ericwbenson]

Hi group,

I have Gemini L4 v1.04 with a G11. The last two attempts at the using the polar alignment correction (PAC) feature in Gemini resulted in the making the alignment worse. The resulting error in elevation was doubled (azimuth did improve however).

Once I gave up after repeated attempts of PAC and used the polar scope I had A:2 E:4 the first time round. I have used this feature extensively in the northern hemisphere to great success. Can anyone in the southern hemisphere confirm that PAC has worked for them with Gemini L4?

Thanks,
EB

[h0ughy]

dont quote me but i think the 1.04 version has a bug and this was fixed in the 1.05 version along with the gps compatability

[ericwbenson]

Small correction, I just checked and I have v1.05.
On Gemini's website they list all the previous bugfixes (http://www.docgoerlich.de/Gemini.html), PAC for southern hemisphere was fixed back in version L3 v1.05, March 2004 ! However I wonder if he accidentally reintroduced the bug, or if I'm doing something wrong. I was hoping someone could corroborate my story before I went to complain to the manufacturer.

[Geoff45]

I did once try PAC with Gemini. It made things worse--decided drift align was a bit longer but at least it worked.

[wasyoungonce]

I had a similar routine on my gotostar system. It gave how much I was out in Alt & Az.

After many many attempts over many many nights (that cost many many hours of observing) to adjust these errors out...I never had any success at all...I gave up. Yet drift align took minutes & was dead accurate.

On that note ...I have never tried polar alignment correction routines on my G11 Gemini because of my previous unsavoury experiences.

Drift align...no problems mate...done in minutes maybe 3/4hr if slow or larger errors!

I suspect these polar align features sound great...but...easier to drift align.

anyway my 2c worth.:shrug:

[browndog]

I had the same problem with the polar alignment correction (PAC) feature in Gemini - it just appears to make the alignment worse.
(maybe this is just a Southern hemisphere feature..)

I have recently tried "Alignmaster" software. It is very simple and quick to use. I have found that it get me very close to alignment - usually within 10-20 arc minutes.

[rsbfoto]

Hi,

I found out that it is not a good idea to correct mecanically exactly to the center. I always correct max 75% of what it should be and so I get better results then correcting 100% eg. putting the star exactly in the crossing of a eyepiece with a corsshair or when using a CCD camera.

Centering mecanically 100% could resuklt in overshooting. Do not ask me why :D

[rogerg]

Interesting. I have tried PAC a couple of times, not recently, but would have been L4 still. I didn't have success with it, but I thought that was just because I needed to understand more about it and was doing something wrong. Perhaps it wasn't just me :shrug:

[ericwbenson]

Thanks for the replies everybody. So it looks like PAC doesn't work down here. I've sent an email to the Gemini developer, hopefully he can confirm the bug and fix it! PAC is a tremendous tool for quick and accurate polar aligning, when it works ;)

EB