From: [email protected] [mailto:[email protected]] On Behalf Of Brendan Smith
Sent: 26 April 2020 02:22
To: [email protected]
Subject: Re: [Losmandy_users_io] McLennan gearbox PE results

?

Yes its supposed to be "unguided"
--
Brendan

From: [email protected] [mailto:[email protected]] On Behalf Of Brian Valente
Sent: 25 April 2020 21:40
To: [email protected]
Subject: Re: [Losmandy_users_io] McLennan gearbox PE results

?

?

--

Magnus,

If I move the scope to - 90 degrees Dec, it will point straight into the ground, wouldn't it? TO the south celestial
pole.... And I could to that if I lived on the equator....

Dec = -90 is not straight at the ground unless you are at the north pole. :-)

For example, if your latitude is 40 degrees then the north celestial pole is 40 degrees above the horizon. The horizon at due south is -50 degrees latitude, and south celestial pole 40 degrees below the southern point of the horizon (not 90 degrees south of it).

-Ray Gralak
Author of APCC (Astro-Physics Command Center):
Author of PEMPro V3:
Author of Astro-Physics V2 ASCOM Driver:

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Magnus Larsson
Sent: Tuesday, April 21, 2020 7:19 AM
To: [email protected]
Subject: Re: [Losmandy_users_io] Side-of-pier issue

Hi!

OK, I see what you mean by declination axis. Just to understand, though:


"Mechanical zero HA/Dec will be one of the two ways of pointing at the intersection of the celestial equator and
the local meridian. In order to support Dome slaving, where it is important to know which side of the pier the mount
is actually on, ASCOM has adopted the convention that the Normal pointing state will be the state where a
German Equatorial mount is on the East side of the pier, looking West, with the counterweights below the optical
assembly and that pierEast <
standards.org/Help/Platform/html/T_ASCOM_DeviceInterface_PierSide.htm> will represent this pointing state."

If I place my mount in this position, it will point straight to the south, right? Where the celestial equator intersects
the local meridian - south, in my case ca 25 degrees altitude (I'm at 55 degrees North). So that is zero mechanical
Dec and HA?

If so, how should I understand this?

Normal (pierEast <> )
Where the mechanical Dec is in the range -90 deg to +90 deg

If I move the scope to - 90 degrees Dec, it will point straight into the ground, wouldn't it? TO the south celestial
pole.... And I could to that if I lived on the equator....


So if I in this position, without moving the RA/HA-axis, move the dec to somewhere north - that would be beyond
+90 degrees - then I should have a shift of side-of-pier?

Magnus








Den 2020-04-21 kl. 15:51, skrev Ray Gralak:


Magnus,

Take a look at this link for a detailed explanation:



-Ray Gralak
Author of APCC (Astro-Physics Command Center):
Author of PEMPro V3:
Author of Astro-Physics V2 ASCOM Driver:



-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Magnus
Larsson
Sent: Tuesday, April 21, 2020 6:29 AM
To: [email protected]
Subject: Re: [Losmandy_users_io] Side-of-pier issue

Hi!

Thanks for your reply!

However, I am not sure I understand - which is not surprising because I
find this to be a difficult issue to describe and understand. I think
the hour angle description was the clearest so far, for me...But, I
don't know what Gemini uses to detect a shift of side-of-pier.

I don't follow what you mean by declination and RA-axis position. My
side-of-pier shifts when I slew in RA, not in DEC (don't know how to do
that). Of course my DEC axis moves, since it rotates around the RA axis.
But it is the slew in RA that causes a shift in side-of-pier, as the
counterweight bar (to describe it physically) moves across the meridian.
I guess that is what you mean by "note that when doing that the actual
pier side change occurs when the declination axis passes the celestial
pole to the other side"?

Either way - whichever axis moves and whatever causes the shift in
side-of-pier - maybe I describe it in totally wrong words. But: my PHD2
reacts to a shift in side-of-pier when I slew from some variables to
certain others - without any meridian flip nor a need for any - because
both stars are on either west or east side of the mount. This is my
problem, and it seriously messes up my variable sequences.

Maybe I describe it in odd ways - but the unusable images are very
real.... so how can we describe it in a reasonable way, and maybe find a
way to handle it?

Best,

Magnus


Den 2020-04-21 kl. 14:17, skrev Ray Gralak:

Hi Magnus,

I'm not sure if this has been said before, but "pier side" is determined by declination axis
position alone. It is not

affected by the right ascension axis position, so slewing the mount to "N", "NW", "S", etc. doesn't
provide enough
information to determine side of pier.


Specifically, pier side changes at the celestial pole when the Dec axis passes through 90
degrees (or -90

degrees).


A change in pier side often is associated with the mount "flipping" to the other side but note
that when doing

that the actual pier side change occurs when the declination axis passes the celestial pole to the
other side.


-Ray Gralak
Author of PEMPro V3:



-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Magnus Larsson
Sent: Tuesday, April 21, 2020 2:57 AM
To: [email protected]
Subject: Re: [Losmandy_users_io] Side-of-pier issue

Hi!

How's it going with this? Makes any more sense? On the indi-forum, it is spoken about
in terms of hour angle,
maybe better way. My test shows that between -3 and -9 hours, the side-of-pier shifts
(approximately at -6) and

the

same happens between 3 and 9 hours.


So these are shifts of side-of-pier in situations where there should not be a meridian
flip (and none is initiated).


See the indi-forum thread here:
problem-bug.html

Best,


Magnus




Den 2020-04-19 kl. 18:28, skrev Brian Valente:


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@...>
<mailto: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
portfolio brianvalentephotography.com <>
<>

As far as I know that’s what you’re supposed to do isn’t it?? Run PHD2 with guiding turned on and then give the log to PecPrep to analyse??

?

If I did it wrong – I hide my head in shame …

?

D.

?

From: [email protected] [mailto:[email protected]] On Behalf Of Magnus Larsson
Sent: 25 April 2020 22:02
To: [email protected]
Subject: Re: [Losmandy_users_io] McLennan gearbox PE results

?

Hi!

I've looked at the log file both with the PHD2 log viewer and the PEMPro log viewer, and as far as I can see, this is guided data, not unguided. That would mean that this low PE is after guiding, not the mount's PE.

Are you sure this is supposed to be unguided?

Magnus

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Den 2020-04-25 kl. 22:39, skrev Brian Valente:

interesting

?

this shows the main period as 211 seconds? i'm not sure what to make of that

?

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On Sat, Apr 25, 2020 at 1:34 PM David C. Partridge <david.partridge@...> wrote:

I get that - I think some of the difference is that I hadn't lapped the
bearing in the further worm block for a sliding fit in the earlier data

I no longer have the PHD2 log files for the 2014 PecPrep data.

I've uploaded the log files from yesterday to the website:

</g/Losmandy_users/files/David%20Partridge/PHD2_GuideLog_20
20-04-24_175626.txt>

David

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Magnus Larsson
Sent: 25 April 2020 14:42
To: [email protected]
Subject: Re: [Losmandy_users_io] McLennan gearbox PE results

Hi!

That is really impressive. And a bit odd, isn't it? If I read the graphs
correctly, the first fundamental is far lower in your second situation
(the McLennan boxes). But that fundamental should in principle not be
dependent on gearbox, should it? I mean, the gearbox would contribute
other frequencies, but not the 239 sec one (that seems ti be 243.7 secs
in your graph).

Would it be possible for you to share the PHD2 logfiles, just to play
with and compare with mine in PEMPro log viewer?

Magnus


Den 2020-04-25 kl. 13:35, skrev David C. Partridge:
> You may remember that not long ago I replaced the Losmandy gearboxes on my
> G11 (which had seen better days) with McLennan gearboxes.? All I was able
to
> say at the time about possible improvements was that they were a LOT
> quieter.
>
> Last night was the first opportunity I've had to record the PE data since
I
> fitted the McLennan gearboxes.
>
> I used PecPrep to record the PE over almost six worm cycles, and the
results
> were quite? excellent - far better that I could have hoped for.
>
> With the original Losmandy gearboxes the results I obtained were quite
good:
> 4.83 arc-seconds Peak to Peak
>
>
</g/Losmandy_users/files/David%20Partridge/Before%20PEC%20T
> raining.PNG>
>
> The results from last night by contrast were nothing short of outstanding:
> 1.6 arc-seconds Peak to Peak (RMS 0.33 arc-seconds)
>
>
</g/Losmandy_users/files/David%20Partridge/24%20April%20202
> 0%20PE.png>
>
> This is so good that quite honestly I don't think I'll bother with PEC
> training.
>
> Note that I didn't edit the PecPrep files to enter the gearbox information
> for the McLennan gearboxes (though that wouldn't change the results).
>
> This is using the original worm (not the HP worm) and twin worm blocks,
> ABEC-5 bearings, a Belville washer in the block furthest from the gearbox
> and the bearing in that worm block lapped to a sliding fit.
>
> Keep well and clear skies
> David
>
>
>
>
>

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--

Brian?

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Brian Valente

portfolio