Re: Guiding a mach1 - and pec?

Ron Kramer

Will do. (waiting for stars). RA to 0.  If I can't set 0.  If I can't,  I do not have a guide cable.  I have a guide camera, USB to computer and I believe the guiding is then passed
along through software to phd2 and PHD2 controls the mount.  Not sure how else I can 'cut the cord' so to speak.
Sorry for being so naive about this stuff - I just started in this last April. Guiding was around July. Then all new mount and software a month ago.

On Tue, Oct 31, 2017 at 1:11 PM, chris1011@... [ap-gto] <ap-gto@...> wrote:

I did try to set DEC to 0 - as per your suggestion before but it wouldn't stick - it changed to 1  (is that ok?)
I don't know what you mean by setting DEC to 0.

What I said below was to set the guide aggressiveness in RA to zero in order to see what the actual periodic error is with PEM off. Then do the same with PEM on. Do each one for about 10 minutes which is just over one worm cycle. Then post the guider graph so we can see it. If your guider program cannot set aggressiveness to zero, then just pull the guider connection to the mount out so that guide signals are not sent to the mount.

To determine if you are properly polar aligned you can also do the same with Dec. Turn off Dec corrections but record the guide star drift in your guider graph. That will tell you infinitely more than just guiding. If your Dec drift is more than 1 arc sec for a 5 minute period, then your polar alignment is not good.


-----Original Message-----
From: Ron Kramer ronkramer1957@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Mon, Oct 30, 2017 8:39 pm
Subject: Re: [ap-gto] Guiding a mach1 - and pec?

thanks I'll try this next clear night.
I did try to set DEC to 0 - as per your suggestion before but it wouldn't stick - it changed to 1  (is that ok?)
You say do this for both axis then. Will do.

I assumed that teh "start" of the pec curve would change if he contact with the worm changed place.
I'll figure that's wrong.

Will do. Don't give me to much at once. My memory is shot. I'll likely print the above out and get that step done.

On Mon, Oct 30, 2017 at 7:24 PM, chris1011@... [ap-gto] <ap-gto@...> wrote:

Frustrated , I wondered about PEC.  It was on, and I read it's "recorded" at the shop and to leave it be... it's set.  Well if I disengaged the worm gears (as I do this to balance with no drag) would not the pec be "off"?
No, disengaging the worm from the worm wheel does not change the PE corrections.

I think you are grasping at straws. Please read my other post about polar alignment - try to get it as good as possible so that the guiding program does not need to fight your misalignment drift.

PLEASE read the following and try it (for your sake and the rest of us who are trying to help):

If you have any doubts about the tracking accuracy do this: TURN OFF the guide corrections to the mount by turning the aggressiveness to zero. Your guider will still record the motion of the guide star and will show you the slow drift back and forth of the RA axis caused by PE AND the steady drift up or down of both RA and Dec due to polar misalignment. Once you have that data, take a screen shot and save it, or post it somewhere so we can all see what your basic mount is actually doing sans the complications of the guiding software corrections. THEN do it all again but this time turn on the PE corrections. You should see a marked improvement of the RA wiggles back and forth because the PEM will be correcting most of that and you should have only the steady drift due to polar misalignment. Both of these tests should take 10 minutes at most (one complete worm cycle).

Now you actually have something to work with instead of the performance below that is mixed up with corrections that may or may not be correct. The other advantage to the above test is that it can show you exactly what to do to precision align your mount on the pole. If you want, I can explain again how that is done, and believe it or not, it is really quite simple and straight forward. It is well worth doing drift alignment and need not be difficult at all and take very little time.


-----Original Message-----
From: ronkramer1957@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Mon, Oct 30, 2017 6:09 pm
Subject: [ap-gto] Guiding a mach1 - and pec?

I've now had my 2nd night of stars since my Mach1 arrived. I wanted to concentrate on guiding (since that is why I upgraded from the NEQ6).

I carefully balanced the scope.  Calibrated (PHD2) near meridian/ecliptic.

guiding didn't look good at that location. I moved to another area and wasn't much better. 

Seeing I suspect was horrible. (I Could see a hazy icy ring out around the moon). Maybe that's why it was bad?   So I tried guide assistant in PHD2 (I don't think it uses seeing as it doesn't do actual guiding)? 

The results I think? were very good? 

Hoping my photo will appear above?

Though that seemed to report good things, guiding was very abrupt and lots of zig zags.  Like OVER correcting...  Though I ended up with Dec agression at  9.  (yea... 9).  Could that be normal? 

I was doing 4 second exposures as was recommended here.  HOWEVER I find it very difficult to do this or longer as my camera's gain is already turned down to 10 in order not to over saturate the guide star (and I still get saturation warnings at that).  Any other way to turn down sensitivity so allow 5 second exposures as recommended by Roland?   (ASI290MM)  ND filter added to camera? 

Frustrated , I wondered about PEC.  It was on, and I read it's "recorded" at the shop and to leave it be... it's set.  Well if I disengaged the worm gears (as I do this to balance with no drag) would not the pec be "off"?  Turning pec OFF - looked better...  I did then click RECORD and watched guiding which was a bit better without PEC.  Later I noticed it was engaged again. (once recorded does it then apply that recorded error?)  

I then was getting a lot of star lost errors (I think high thin clouds) as I was in a small gap in days of rain.  Advice?  Wait and try again? the GA feedback is good?   what about PEC.  I read somewhere on here about uploading it to the mount?  Id I recorded it - didn't it auto apply it? 

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