VintageBigBlue.org

 

RE: [Losmandy_users] Pointing to that first star for initial alignment with Gemini


Oct 25, 2001

 


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#6572 Oct 25, 2001

Dear group and particularly Rene:



I am one of those who have great difficulty pointing the OTA to the firststar in order to do an initial alignment with the Gemini.�� This isbecause the R/A and Dec swings of the G-11 equatorial mount are notintuitive to me, and therefore, it takes too much time to figure out howto point using the Hand Controller.



I find that I have no trouble pointing to a star manually, if I loosenthe clutches, nudge the OTA toward its destination, and allow the mountaxes to swing as they will.�� The problem is, that one must not turnon the Gemini for goto operation in any other position than CWD(counterweight down) position, and one must not, thereafter, loosen theR/A clutch.



To make life easier for myself, I devised the following procedure whichseems to work, but I ask anyone who sees an error in it, to call it to myattention.



Preliminary Setup Procedure



I cut a triangular pointer from a yellow self-stick label, andaffixed the pointer to the stationary part of the G-11 frame at aconveniently visible location, pointing to the lower ring of the R/Asetting circle.



Pointing to a Star for Initial Alignment



1. After polar-aligning the mount, I turn the lower ring of the R/Asetting circle until the zero is opposite the yellow pointer.



2. I loosen both clutches, and hand-slew (push) the OTA until it pointsto the star of my choice.�� With the clutches loose, it finds its ownswing positions.



3. While pointing at the target star, I tighten both clutches, turn onthe Gemini, and slew the R/A to the CWD position.�� I do not move theDec.



4. While in the CWD position, I turn off the Gemini and then turn it backon for a cold start.�� I then slew the R/A until the zero of thelower R/A setting circle returns to be opposite the yellow pointer.



I am now back to the vicinity of my target star.�� I center the starwith the Hand Controller, and do an initial alignment.�� After that,I using the Gemini's goto abilty to point to subsequent stars foradditional alignments.



If this is a useful procedure, perhaps the G-11 should include a pointeron its frame pointing to the R/A setting circle as part of itsmanufacture.



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#6576 Oct 25, 2001

IMHO:You seem to be devising a complex means of dealing with a simple ,low

cost solution.Check out a Telrad.They are 30 dollars and last a

lifetime.Once mounted and aligned,from there on you can stand behind your

scope and see a laser-like bulls-eye and just slew in whatever direction to

get the star of your choice into the 20 ring.







Clear skies...good eyes



JImmy



www.frenchriverobservatory.com







----Original Message Follows----

From: Michael Rudolph mrudolph@...>

Reply-To: Losmandy_users@yahoogroups.com

To: Losmandy_users@yahoogroups.com

Subject: RE: [Losmandy_users] Pointing to that first star for initial

alignment with Gemini

Date: Thu, 25 Oct 2001 17:02:29 -0400



Dear group and particularly Rene:



I am one of those who have great difficulty pointing the OTA to the first

star in order to do an initial alignment with the Gemini. This is because

the R/A and Dec swings of the G-11 equatorial mount are not intuitive to

me, and therefore, it takes too much time to figure out how to point using

the Hand Controller.



I find that I have no trouble pointing to a star manually, if I loosen the

clutches, nudge the OTA toward its destination, and allow the mount axes to

swing as they will. The problem is, that one must not turn on the Gemini

for goto operation in any other position than CWD (counterweight down)

position, and one must not, thereafter, loosen the R/A clutch.



To make life easier for myself, I devised the following procedure which

seems to work, but I ask anyone who sees an error in it, to call it to my

attention.



Preliminary Setup Procedure



I cut a triangular pointer from a yellow self-stick label, and affixed the

pointer to the stationary part of the G-11 frame at a conveniently visible

location, pointing to the lower ring of the R/A setting circle.



Pointing to a Star for Initial Alignment



1. After polar-aligning the mount, I turn the lower ring of the R/A setting

circle until the zero is opposite the yellow pointer.



2. I loosen both clutches, and hand-slew (push) the OTA until it points to

the star of my choice. With the clutches loose, it finds its own swing

positions.



3. While pointing at the target star, I tighten both clutches, turn on the

Gemini, and slew the R/A to the CWD position. I do not move the Dec.



4. While in the CWD position, I turn off the Gemini and then turn it back

on for a cold start. I then slew the R/A until the zero of the lower R/A

setting circle returns to be opposite the yellow pointer.



I am now back to the vicinity of my target star. I center the star with

the Hand Controller, and do an initial alignment. After that, I using the

Gemini's goto abilty to point to subsequent stars for additional alignments.



If this is a useful procedure, perhaps the G-11 should include a pointer on

its frame pointing to the R/A setting circle as part of its manufacture.





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