I did an initial rough PA and then used the RAPAS and the app to complete the fine alignment.  Using my UltraStar camera at f/5,  I did a drift test on Sirius as it was low in the southeastern sky and it remained centered for 5 mins before I noticed any drift.  Then I did the same with Menkar just off the meridian and near the celestial equator and it only stayed centered for about 1 and a half minutes.

Start by adjusting the azimuth axis until a star at the meridian near the celestial equator does not drift in Dec. Once that is done, you have half of your alignment finished and won't need to adjust the azimuth any further.

Now all you need to do is adjust the altitude axis. Choose a star near the zenith and raise or lower your altitude axis until that star does not drift in RA. Your mount is now polar aligned and drift is zeroed out over a large portion of the sky.

Now you can adjust the RAPAS alignment so that it puts Polaris at the right point on the scale. From then on you won't have to do the drift align procedure, just use the RAPAs and you should be very close to the pole each time.

Rolando

-----Original Message-----
From: donza2735@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Wed, Dec 13, 2017 7:58 am
Subject: [ap-gto] Need advice with new Mach1GTO: Polar Alignment and drifting

I just bought a Mach1GTO for my de-forked C11" and am still feeling out how the mount works.   I also bought the RAPAS for PA.  The scope is balanced and it is leveled in the E/W direction. 

 I did an initial rough PA and then used the RAPAS and the app to complete the fine alignment.  Using my UltraStar camera at f/5,  I did a drift test on Sirius as it was low in the southeastern sky and it remained centered for 5 mins before I noticed any drift.  Then I did the same with Menkar just off the meridian and near the celestial equator and it only stayed centered for about 1 and a half minutes.  I then looked once again on the RAPAS and Polaris seemed spot on compared to the app.  So, I am concluding from this that the RAPAS needs to be realigned as AP suggests could be the case. My question: What is the simplest and best way to do the drift alignment which I have never done? 

I am a Mac user and I am aware that AP highly recommends PemPro which is a Windows program vs. doing the drift alignment manually.  I also realize that the simplest and best ways may not be the same.  I do have an Intel compute stick with Windows 10 if folks think PemPro is the way to go.  

Thanks in advance,

Bruce