Hi!
Let me take SW to NW as an example instead:
I slew from RR Tau to GM Cam. This is from:
05 39 30.51??? +26 22 27.0
To:
03 59 10.08??? +58 01 07.7
At around 10pm (at my location, but that should be same for you,
shouldn't it?), that means slewing from somewhere roughly SW to
more NW - and in doing this slew, the mount shifts side-of-pier -
roughly as it crosses 270 degrees azimuth.
Roughly, I stay at an altitude of around 30 degree, and slew on
the western side of the sky. Then the slew is both in RA and Dec.
Does that help?
Simulate on for instance CdC, and I think you will see what I
mean. And I'm at latitude 55 degrees North.
Magnus
Den 2020-04-19 kl. 18:28, skrev Brian
Valente:
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I generally understand your somewhat unusual case
What i don't understand is this: when I want to go from NE
to SE, that is a slew in DEC for me. you're saying slew in RA,
and I don't see how i would get to SE just by moving RA?
On Sun, Apr 19, 2020 at 9:19
AM Magnus Larsson <
magnus@...> wrote:
Hi!
No, it is a slew in RA - I'm doing it with the same
declination, just slewing in RA, to test. And right, no
crossing the meridian. But physically, crossing the 90
degree azimuth line, the counterweight bar crosses to the
other side of the mount - hence shift of side-of-pier, in
a very literal sense.
Yes, it impacts my guiding since when the mount reports
shift of side-of-pier, PHD2 swaps direction of RA guiding.
But since no direction of the guidecam or otherwise in the
mount has happended, this means that RA now escalates
errors, rather than works against them - hence escalating
run away scope.
In essence, PHD2 interprets shift of side-of-pier as a
meridian flip. But this is not the only case when it
occurs nor when the G2 reports it.
It took me quite a while to see this... And I guess this
is not what would be problematic in regular AP, when you
find a target, maybe calibrate, and then track for hours.
Then there is a meridian flip, RA shifts, and back to
tracking. It happens here because I slew from target to
target, imaging 20-25 different targets with just one or
two subs of each, but I need guiding because I do some 5
mins exposures and I get too much drift if no guiding. I
have my complex sequence set up so it goes from lower
altitude to higher, picking stars before they are too low,
basically, and then waiting for some to rise some more
(manually sorted). It means that it will start out on the
west side, going in sort of zig-zag motion from RR Tau to
GM Cam, to YY Aur, to U Gem and so on.
Do you see it now? Or what can I send or describe that
makes it more clear?
Best,
Magnus
Den 2020-04-19 kl. 17:48, skrev Brian Valente:
Hi Magnus
No, it doesn't really make sense to me.? if i go from NE
to SE, this is just a DEC move, i'm not crossing the
meridian. So why would it report side of pier change?
confused abou tthis
i can slew back and forth, but it sounds like your issue
is how is guiding impacted, correct?
So i would assume you need some guiding to take place in
this situation to see how it impacts.
--
Brian?
Brian Valente
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