Re: [APML] APML Gemini GoTo and Autoguiders???

["Jeff Crilly" <jlcapml@sbcglobal.net>]

----- Original Message ----- 
From: <KGKIRKLEY@aol.com>
> 
> The maximum Guide rate for DEC in the Gemini is 0.8x the Sideral rate and it 
> appears this is to slow to move the guide star an appropriate amount.
> 

(First, I dont use the Gemini+st-4/v, but I use a ST7E+CCDOps for autoguiding a G11-standard.)
(Second, I am no expert, but here is what it  seems to me....)

Hmm.  If 0.8x is "to slow to move the guide star", then I'm thinking
the guidescope is maybe too short.  

What size guidescope are you using?

Or the calibrate movement time is simply too short.  

With my 200mm f.l. guidescope I set the G11 to 0.5x and make the
autoguiding-calibrate-move-time 20 seconds.  

My ST7E chip is alot bigger than the ST4 , but not much bigger than a STV (237A).
So, I expect the ST4 would need maybe 10 seconds(?)

I have a heck of a time calibrating.  My main problem is that
CCDops gets confused with multiple stars in the FOV during calibration.

If there is _one_ bright star in the FOV, and its fairly centered
so it doesnt fall off the chip, then calibration works.

Occasionally I have a problem where guiding corrections are going in 
the "wrong" direction.  Usually this is if I calibrate in the east and then
later image in the west... I think.  Anyhow, I always calibrate just before 
an imaging run so I rarely see it.

As for the "calibrate in 0.8x and guide in 0.5x".. this effectively
sets the "aggressiveness" for the guider down a bit.  My understanding
is that the ST4 has no "agressiveness" like the CCDOps/CCDSoft/MaximCCD
software does... I beleive the STV has adjustable agressiveness, but dunno for sure.

jeff

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