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Start the alignment process with the center switch routine and time entry. Then select the first alignment star. When the scope stops slewing, rather than manually slewing to center the star, adjust the mount's knobs in azimuth and altitude until the star is centered.

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That is how I start my initial alignment procedure with the Paramount ME. The only reason this works is because the homing function of the ME is very accurate and repeatable (within an encoder tic or faction of an arcsecond). The scope always starts out in the exact same place.

I start by leveling the mount, and then home it by tapping the joy stick button twice. After that I just slew to a star (preferably near the celestial equator) and then adjust the mount’s Alt and Az knobs until the star is centered. (I have also done this during the day using the Sun).

This procedure also assumes the mount's time and date are accurately set since it goes to where it thinks the star should be. It also assumes you don’t have excessive backlash issues either.

With my current setup and a CCD camera attached to my OTA at 2500mm FL I can get and initial poler alignment within about 10 arcminutes (which is about 1/3 the size of the moon). Most of the error here is due to the mirror position in my SCT OTA and the non-perpendicularity alignment error of the OTA to the Dec Axis of the mount.

After this rough alignment I do a iterative polar alignment and end up with an alignment of less than 1 arcsecond error. (I don't do drift alignments).

Since my mount is permanent the iterative alignment is followed by a T-Point run which allows 10 minute unguided exposures with my 4” refractor. T-Point will also tell me how far off my polar alignment is and how many tics to turn the knobs on the Paramount to correct it.

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-Marcus

The problem with free speech is even the stupid have a voice.

http://jatobservatory.org


12" LX200R on a Paramount ME

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That is how I start my initial alignment procedure with the Paramount ME. The only reason this works is because the homing function of the ME is very accurate and repeatable (within an encoder tic or faction of an arcsecond). The scope always starts out in the exact same place.

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Below is a screen shot from TheSky of my horizons, centered on the zenith with the line from center top to bottom being the meridian - what I can see is in black. Hence my problem. I'm just trying to get close enough that the software can take over and lead me from there. Right now I think I'm so far off that the software is having trouble helping me.

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If what I was thinking doesn't work, then it doesn't work. But I really am just looking for a rough alignment - a starting point.

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How about a small modification to your idea... start with the mount in home (or park) position and do a 1 star alignment. Try to pick a star near the equator on the side of the sky you are thinking of working in.

However, instead of lining the mount directly up on the star, adjust the mount only 1/2 to 3/4 of the way towards the alignment star. Then home (or park) the mount and repeat this process until the star hits dead on in your one star alignment.

See if my reasoning for this makes sense to you - if you adjust *all* the error out then when you do the second iteration your mount absolutely *must* either travel past your star (if you had to move the mount toward your star to line it up), or fall short of the star (if the mount originally overshot the star) because the true "aligned" position of the mount is going to end up being somewhere in between the point you started at and where the mount is after your first adjustment (assuming that you centered the star the first time). Subsequent adjustments will go back and forth across the point where the mount would actually be "aligned", but it is not certain that you would eventually split the difference because it isn't certain that the actual point where the mount is in "alignment" is exactly centered between your starting point and that first adjustment point. Cutting the correction in half or by 3/4 should help minimize this and hopefully help you creep up on the actual "aligned" point without having to chase your star around with the mount all night.

You should know it is working okay because after the first adjustment your adjustments should continue in one direction for at least one or two iterations and then reverse as you go past the "aligned" point. If you find you are going back and forth then it should be by very small increments that decrease with each iteration. If you find you are swinging back and forth in big adjustments then correct less until it starts going in one direction again.


Charlie

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Weston CSC:

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Marcus,

So it sounds like it could work for me, providing the CGE's switch routine has sufficient accuracy.

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Chris,
It is worth a try. You would of course have to substitute drift alignment for the iterative alignment since you can't see Polaris.

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-Marcus

The problem with free speech is even the stupid have a voice.

http://jatobservatory.org


12" LX200R on a Paramount ME

Edited by JAT Observatory (10/23/06 06:33 PM)

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Charlie,

I've got to read that another time or two to let it sink in fully, but I think that makes a lot of sense, and in fact it may explain some of why I feel I've been chasing my tail with what I've been doing. Thanks for the suggestion.

Clouds tonight but should be clear the next couple of days so I will hopefully make some progress then. No Polaris and 50-60 degree E & W horizons sure don't make this easy!

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I imagine so... good luck!

Charlie

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Weston CSC:

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