Re: RA rate drift (revisited)
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Hi Ray,
Thanks for that ...I did understand that but....
I somehow missed the statement that the first step:? get AZ correct by the drift method, while pointed at Meridian and Equator, must already be accomplished.?
Then I understand adjusting ELevation at the zenith...as long as AZ is right the only remaining error must be EL.??
I like that idea and will try it, since my East and West are totally obstructed.
Sorry for my mis-reading.
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I wonder though...did the original question about mount tracking too fast and too slow in East and West...did that puzzle ever get solved?
Best, Michael?
?
> When using the PHD2 drift tool, it is only the DEC drift you want to null out (not RA drift),
> as that tool says in its instructions.
Yes, but as Greg said, this technique is different in that it uses RA drift at the zenith to adjust Altitude polar alignment instead of standard Dec drift in the East or West.
There are advantages and disadvantages to this method, but the intent is to null out RA (and Dec) drift near the meridian, which is where usually the best quality images can be obtained.
-Ray Gralak
Author of APCC (Astro-Physics Command Center):
Author of PEMPro:
Author of Astro-Physics V2 ASCOM Driver:
Author of PulseGuide:
Author of Sigma:
> -----Original Message-----
> From: Losmandy_users@... [mailto:Losmandy_users@yahoogroups.com]
> Sent: Sunday, November 5, 2017 1:16 PM
> To: Losmandy_users@...
> Subject: Re: [Losmandy_users] Re: RA rate drift (revisited)
>
>
>
> Hi Greg,
>
> Thanks for the notes.
>
> When using the PHD2 drift tool, it is only the DEC drift you want to null out (not RA drift), as that tool says in its
> instructions.
>
> [ repeat these 2 steps...
>
> When you are pointing first near meridian and celestial equator, only adjust the AZ knobs.
>
> When pointing next, as far East or West as possible, then again look only at DEC drift, and null out with the AZ
> knob.
>
> ]
>
> Repeat...[...] til you are satisfied.
>
> You really don't need to bother about the PEC... you can ignore errors in that for the drift alignment (by PHD2
> anyway).
>
> Best,
> Michael
>
> On Nov 5, 2017 1:03 PM, "beneckerus@... [Losmandy_users]" <Losmandy_users@yahoogroups.com>
> wrote:
>
>
>
>
>
>
> This subject is a current topic on the Astro-Physics group (#59424) and the subject of using PHD2 was
> discussed. PHD2 displays both the DEC and RA drift in the Drift Alignment tool. So instead of letting PHD2 slew
> the scope to the East for the altitude adjustment, slew it manually to the zenith. Turn on your mount's PEC to
> minimize RA motion. Run the drift session for a full worm cycle to cancel out the effects of the remaining PE.
> Adjust the altitude to minimize the RA drift. There is no point in doing the Eastern altitude adjustment first as this
> will always change for the minimum RA drift adjustment.
>
> I found it interesting to think about this at the limit of doing polar alignment at the equator, where the
> intersection of the celestial equator and the meridian is also the zenith. Using this method there you would not
> move the scope from the zenith for either adjustment
>
> Greg
>
>
>
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Michael Herman