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"Speed" to use when building a model

 

Took my relatively new GM811 out and tried my first attempts at building a model and doing GOTO's.


Have used the mount in the past, but never played with the GOTO capability or building a model.? All did not go well.


Had some issues, GOTO's were always out by a few degrees.? Familiar with GEM mounts, polar alignment and such, just new to GOTO's.? All the initial parameters; lat, long, time offset, date and time were all entered correctly.? And my CWD was set initially as best as I good visually set it.? A Polemaster was available, so we even used that for Polar alignment.


But, yes,?did not fully work my way through the Gemini-2.com website beforehand.


In hindsight, and working through the website, I found this comment ...


WARNING: ONLY USE THE CENTER OR GUIDE SPEED TO CENTER THE STAR. USING SLEWING SPEED WILL TAKE YOU OUT OF THE MODELING FUNCTION AND RETURN YOU TO NORMAL GOTO MODE.


To center the star to model I would use the "MOVE"? speed.? The comment above is explicit about NOT using SLEW because it takes you out of the modeling function, and explicitly says to use CENTER or GUIDE.? But what about "MOVE".? Would using "MOVE" not allow me to build a model?


Could this of been a source of my trouble?


Also to center a star, didn't use a cross-hair or anything like that, just did a visual "close enough to the center of the field of view" at about 80x magnification.? When you have to "center the star" how close is close enough?


Thanks in advance...


... Bill
 

Bill

the speed has nothing to do with building the model. you just need to accurately center the goto target. it's tricky to do with slew or move, but it can be done. the more accurately centered, the better your model

it's just easier to just center, it's a slower speed. that's the only difference



B
 

Thanks,?

This probably should be posted over in the Gemini-II forum.? So, just shut this down and I'll re-post over there.

Sorry....

... Bill
 

Somewhere in the Gemini1 manual it says something like...:

Align to 3 stars on one side (only) of the meridian? (go West of meridian and align to 3 stars).

Then, after those 3 on one side, align to 3 stars on the other side (say East of meridian).

Give that method a try and see if your pointing gets better.

Also be aware of the difference between the words "Align" and "Synch."? A "Synch" only adjusts the offsets of RA and DEC, but does not change the Model parameter values.? "Align" does not change the RA or DEC offsets, but instead adds new calculated Model parameter values.

On a cold boot, all Model parameters are 0.? After your first star Align/Synch, the values are still 0...only the offsets are adjusted.? Each "Align" after that Gemini actually does calculations of the Model.? You can watch the model values change after each step, if you use the Gemini.net applet for example.

I don't have the software source code, but the data fitting algorithm method must be why the 1st 3 "Align" stars must be on the same side of the Meridian....so the calculations come out right.

Other mounts do not have this requirement, or use triangulation rather than a sophisticated sky model.??

Anyway...see what your tests show.

Best,
Michael?



On Oct 24, 2017 11:18 AM, "bill.krosney@... [Losmandy_users]" <Losmandy_users@...> wrote:
?

Thanks,?


This probably should be posted over in the Gemini-II forum.? So, just shut this down and I'll re-post over there.

Sorry....

... Bill

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