Re: PemPro-V2 versus ASCOM RA-Backlash

Christopher Erickson

Unless there is some imbalance in the RA axis.

I have seen some mounts (no AP mounts yet) "bouncing along in the backlash"
when pushing the OTA "downhill"

Of course this would look completely different than simple orthogonality

But if the imbalance was great enough then it could simply wrap the backlash
to the other side of the gears when on the other side of the meridian.

Just thinking out loud.

Christopher Erickson
Consulting Engineer
Summit Kinetics
Waikoloa, HI 96738

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...] On Behalf Of
Ray Gralak (Groups)
Sent: Saturday, April 19, 2014 9:29 AM
To: ap-gto@...
Subject: RE: [ap-gto] PemPro-V2 versus ASCOM RA-Backlash


It can't be RA backlash. The mount is always tracking forward so backlash in
RA is always removed.

-Ray Gralak
Author of Astro-Physics Command Center (APCC)
Author of PEMPro:
Author of Astro-Physics V2 ASCOM Driver:
Author of PulseGuide:
Author of Sigma:

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...] On Behalf Of
Joseph Zeglinski
Sent: Saturday, April 19, 2014 12:25 PM
To: ap-gto@...
Subject: [ap-gto] PemPro-V2 versus ASCOM RA-Backlash

Hi Ray,

I wanted to try using ASCOM "RA Backlash" setting to see if I could
remove my AP-900's 28 arc-minute meridian
flip error (in recent "GOTO error" discussions).
To that end, I thought that the PemPro Backlash Wizard would provide an
accurate test to determine the precise
compensation for use in the ASCOM driver.

However, I discovered that PemPro, for some reason, only provides DEC
backlash analysis.
Is the reason for missing the RA backlash, caused by other complicating
factors in RA, such as PEC error and polar
alignment, which just adds to the confusion of singling out the RA gear
backlash component?

Since PemPro won't do an "RA Backlash" analysis and provide a
compensation value, what software does?
Also, while I admit I am not pleased with such a sloppy (floppy?) 28
arc-min error, and probably should hammer the
worm back in closer, would it be useful, to stretch the RA & DEC backlash
entry box to maybe a 2 arc-minute ( 120
arc-sec rather than 59) value?
Jeff wrote recently that he has a 30 arc-minute meridian flip error -
possibly also due to backlash, so I am not alone
on this.



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