RAPAS Use


Emilio J. Robau, P.E.
 

Here is a stupid question.  I now do preliminary alignemnt with the RAPAS.  I then go to NINA and do their three point alignment, which by the way puts things spot on as best as I can tell.   The procedure is pretty automated.   Once I get polar alignemnt, can I take the RAPAS off?   The plate below it is what is aligned to the pole.   I guess if I take the RAPAS off it may misalign some, but if I am doing NINA three point anyways, this should not matter.  Is this all correct?

Even if I take the RAPAS off and put it back on later, the alighment should be pretty good no?

Thanks in advance for a reply.  I have been preparing to go mobil for months now and have things pretty well in order.  I wanted to see if I can take the RAPAS off becuase it protudes a bit and with my newtonians and camera down things get in the way.


ap@CaptivePhotons.com
 

On Fri, Dec 2, 2022 at 08:02 PM, Emilio J. Robau, P.E. wrote:
Once I get polar alignemnt, can I take the RAPAS off? 
Yes.  There's even a fairly clear indication that is expected in one of the manuals, but more to the point I found that mine would hit the OTA's imaging train at some angles if not removed.

I asked the same question but can't find that topic now.

Linwood


Emilio J. Robau, P.E.
 

You are absolutely right Lynwood.   That is why I want to take it off.   I can set up the mobile unit both on my CBS Slab balcony and get a pretty nice view of the very southern skies.   However, if I go too far south the imaging train which hangs down below both reflectors the home brew 10" newt and the Tak.

Preliminary with the RAPAS and final with NINA.   I think that is the way to go for fairly precise alignment on the go.  The observatory is spot on, but it is permanent and the alignemnt has not changed in years.  Luckily I have a huge pier foundation deep deep into the sand.


ap@CaptivePhotons.com
 

On Fri, Dec 2, 2022 at 08:23 PM, Emilio J. Robau, P.E. wrote:
Preliminary with the RAPAS and final with NINA.   I think that is the way to go for fairly precise alignment on the go.  The observatory is spot on, but it is permanent and the alignemnt has not changed in years.  Luckily I have a huge pier foundation deep deep into the sand.
FWIW your nearby dark site at Big Cyprus has a nearly exactly north/south road beside the field we use. I get plenty close by eye to use NINA.  The 1100 has a very generous azimuth adjustment range.

It was very thoughtful of those rangers to design the road so as to aide in our initial polar alignment.  :) 

Linwood


Chris White
 

"Use it and remove it"

It'd right in the manual. Also it states that the machining is precise enough that removing and reinstalling will reliably produce the same accuracy over and over again. 


Emilio J. Robau, P.E.
 

Thanks,

I apologize for not looking in the manual first.   I am a lazy man.

Appreciate the help.  I try to minimize these sorts of things.


Antoine PAVLIN
 

Hello,

 

I personally do a first polar alignment with the RAPAS that gets me close to perfect alignment (about 1’ of the true celestial pole).

 

This was so far enough for all my astrophotography activity, but recently I added one step, also as you write to avoid my camera to hit the RAPAS in some orientations: I remove the RAPAS and do the three points star alignment with NINA that fine tune this polar alignment.

 

Clear skies

 

Antoine

 

De : main@ap-gto.groups.io <main@ap-gto.groups.io> De la part de Emilio J. Robau, P.E.
Envoyé : 3 décembre 2022 02:02
À : main@ap-gto.groups.io
Objet : [ap-gto] RAPAS Use

 

Here is a stupid question.  I now do preliminary alignemnt with the RAPAS.  I then go to NINA and do their three point alignment, which by the way puts things spot on as best as I can tell.   The procedure is pretty automated.   Once I get polar alignemnt, can I take the RAPAS off?   The plate below it is what is aligned to the pole.   I guess if I take the RAPAS off it may misalign some, but if I am doing NINA three point anyways, this should not matter.  Is this all correct?

Even if I take the RAPAS off and put it back on later, the alighment should be pretty good no?

Thanks in advance for a reply.  I have been preparing to go mobil for months now and have things pretty well in order.  I wanted to see if I can take the RAPAS off becuase it protudes a bit and with my newtonians and camera down things get in the way.


Sans virus.www.avast.com


Howard Ritter
 

Apologize? Lazy? I don’t know, but not to RTFM is SOP for every PE I know!

– howard


On Dec 2, 2022, at 11:51 PM, Emilio J. Robau, P.E. <ejr@...> wrote:

Thanks,

I apologize for not looking in the manual first.   I am a lazy man.

Appreciate the help.  I try to minimize these sorts of things.


Dean S
 

I use mine with 4 mounts and it works perfectly after setting up the back plates on each mount. 




On Dec 2, 2022, at 11:14 PM, Chris White <chris.white@...> wrote:

"Use it and remove it"

It'd right in the manual. Also it states that the machining is precise enough that removing and reinstalling will reliably produce the same accuracy over and over again. 


M Hambrick
 

Hi Emilio

My lessons learned with the RAPAS on an 1100 GTO mount (for whatever it's worth):

Make sure that the RAPAS is properly seated in the back plate before tightening the screws. I attached mine incorrectly one time when I was setting up after dark. I couldn't figure out why my guiding was so bad until I took everything down and noticed that the RAPAS was not flush with the back plate.

Do not over tighten the screws. If the RAPAS is properly seated in the back plate, all you have to do is snug the screws to hold it in place. Just barely finger tight is good enough.

I used to set up my scope in Park 3. It is impossible to use the RAPAS from this position with the scope attached, so I would polar align the mount before everything was attached. In a portable setup this is not always a good thing because a slight bump when attaching the scope can (and has) messed up the polar alignment. If you have a portable setup, do so with the mount in Park 2. This way you can get everything attached and positioned, and still be able to look through the RAPAS eyepiece to do the polar alignment. DO NOT forget to remove the RAPAS after you have polar aligned. If you have a short scope with a camera attached, you will likely collide with RAPAS the first time you slew the scope.

Mike 


Roland Christen
 

Of course you can take it off. That's the way it was designed, to be removed after use. It will keep its alignment.

Roland



-----Original Message-----
From: Emilio J. Robau, P.E. <ejr@...>
To: main@ap-gto.groups.io
Sent: Fri, Dec 2, 2022 7:23 pm
Subject: Re: [ap-gto] RAPAS Use

You are absolutely right Lynwood.   That is why I want to take it off.   I can set up the mobile unit both on my CBS Slab balcony and get a pretty nice view of the very southern skies.   However, if I go too far south the imaging train which hangs down below both reflectors the home brew 10" newt and the Tak.

Preliminary with the RAPAS and final with NINA.   I think that is the way to go for fairly precise alignment on the go.  The observatory is spot on, but it is permanent and the alignemnt has not changed in years.  Luckily I have a huge pier foundation deep deep into the sand.

--
Roland Christen
Astro-Physics


Scott
 

Just to give my experience with my mobile setup, it's no issue to turn the scope out of the way to look though the RAPAS as park 3 is at DEC. 90deg. and easy to put back. Also, the mount (in my case AP1200) only needs to be close. I once put Polaris in the spot for the southern hemisphere instead of North and had no effect on my guiding for the night from Calif.


Emilio J. Robau, P.E.
 

Last night I practiced setting up in preparation for the field and after the moon set, about four hours of data.   Anyways, first took the RAPAS off.  Moved the mount a bit.  Placed it back on.   Leveled the mount, sighted in Polaris to the correct location.  Did not bother to refine.  Went into NINA and refined it there.   My total error ended up being around 17 seconds.   The thing that took the longest was estimateing the deflection caused by tightening up the bolts that tighten the mount.  I now have a good feall for it.  I was nearly spot on.  Very easy and very effective.


Chris White
 

If you run a model in apcc or guide you probably don't even need to refine with Nina.  


Christopher M
 
Edited

I was wondering about this (RAPAS is removable and returnable w/o impact to accuracy).  My previous mounts from other mfrs had their polar 'scopes fixed, so I thought it would be the same.  Good to know that I won't loose Through the Mount Cabling when using a RAPAS now.  👍