Re: AP1100 autoguiding


OlivDeso
 

Hello Christophe

The pointing is usually 15-20 arcmin off, on any target in the sky, and, last night, I tried to image M101, and saw that the derive is something like 30" per hour on such a target. The max exposure time I could do was 60sec at 1900 mm focal length.


by "dérive" which is the French word, do you mean drift I guess, so you get trailling stars.

Do you know I which direction? RA? DEC? or both?

Drift along DEC -> polar align is not good enough  -> perform a very acurate drift aligment using pempro, then fine tune the rapas
Drift along RA axis -> PE -> perform gear remeshing, then PE measurement with pempro and then upload PEC from pempro to the mount


There are 2 things to do to improve the PE :

1) gear re-meshing : first of all, before any PE measurement, it is very important to have a proper gear meshing, especially if the mount has travelled and/or was used at a different temperature.

-> follow the AP procedure here, it isvery simple and very efficient.




On to of that, I 'd like to mention a trick : on the forst AP1100, I found the CP3 motor spring loader to be a little bit to strong. It fact it comes from the screw which secure the spring : the thread is a little bit too short compared to the spring length. Not a big deal for DEC, but significant for RA.

My advise : on these older AP1100, while tuning the RA mesh, unscrew the spring holding screew by 2 turns, not more. and follow the AP procedure.
It will ensure applying just the needed pressure to get the best meshing and lowest EP.
Once this gear meshing is done, you can 

2) Once gear mesh has been properly set, you can run pempro and measure the PE.
- first polar align precisely enough, using the drift alingment tool
- measure the PE between +1° and +5° after the meridian, not more. "rewind" if needed



Are the RJ11-6 and RJ12 plugs compatible ? -> yes, in fact RJ11 is the 4 contacts version of the RJ12 

(RJ11 6 positions 4 contact (6p4c) and RJ12 6p6c. So RJ11-6 is a wrong naming, the right naming is RJ12 for 6p6c RJ plug)

Now since you have the CP4 ou CP3, you could also use the pulse guiding whicjh is a little bit more acurate than the ST4 : the mount itself manages the pulse duration. Thought in this particular case, the difference is likely to be marginal with the Lacerta Mgen. (it could be more signigficant with an old PC)


clear skies

Oliv Deso

Le lundi 2 mai 2022, 05:26:56 UTC+2, christopheciel via groups.io <christopheciel@...> a écrit :


Dear all,


My name is Christophe, from France.

This is my first message here.

My english is not very good, as you will see ; I hope you will understand what I mean.


This forum is a great idea.


**


I bought a used 1100 GTO a few months ago from a very nice person, who had it in a small observatory.

This precedent owner had a CP3, then he bought a CP4. He never actualized the PEM, so there is none, using only the mount with a PC and an autoguiding camera to image.


After a couple of weeks of use, I still have some issue with the pointing and tracking. I use only the keypad. The pointing is usually 15-20 arcmin off, on any target in the sky, and, last night, I tried to image M101, and saw that the derive is something like 30" per hour on such a target. The max exposure time I could do was 60sec at 1900 mm focal length.


I calibrated the RAPAS as indicated in the rapas notice, and the mount is leveled as perfectly as I could.


Well, I'm now looking for an autoguiding camera in order to enhance the tracking.


I have a old LACERTA MGEN stand alone autoguiding camera.


https://en.lacerta-optics.com/MGEN_Lacerta-MGEN-II-Superguider-Autoguider-Camera-with


The out plug of this system is an ST4 or RJ12 male plug. I understand that the autoguiding female plug on the CP4 is a RJ11-6 plug.


Are the RJ11-6 and RJ12 plugs compatible ?


So had some of you ever used a same lacerta mgen system on a 1100 GTO ? Do you think this is possible ?


Or should I avoid to use this camera and buy another on ? I have a limited budget right now, alas.


Thank you so much for any help or advice.


Christophe


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