In a message dated 10/25/04 1:41:23 AM, twade@bmi.net writes:
Wade:
Sorry for the previous absent post, but my browser was acting very strange and I also needed to turn on and check my STV for some of the settings I use.
Kent,
<<When doing your drift aligning, how long are you going before the selected stars move off the reference point?>>
What do you mean by reference point? I use the STV for polar alignment using the Drive Monitor Slow option (i.e. it mimics the drift alignment method).
By reference point I mean the the center of the crosshairs of a guiding eyepiece.
While I know there are other ways to drift align, I still polar align my AP1200GTO using first the polar alignment scope and then the 'tried and true' drift alignment method using a guiding eyepiece and drifting on two stars, first one just east of the meridian about 20 degrees higher that the celestial equator and second a star in the eastern sky. If I get no drift in the 15 minute range for each star, I am very well aligned. This insures no field rotation and low tracking errors.
I'm using an AP 900GTO mount so it should track accurately. I'll try the manual calibrate and track methods to see if I get better results. Do you have any parameter values you would recommend when using the manual methods?
First, in the AP hand controller, set-up, set the DEC backlash to '0'.
Set the guide speed to '1'.
In the STV, Manual Track menu, set to Full Menu
Relay Tone, on or off
Exposure, set shortest exposure that gives healthy brightness reading, ie. over 1000
Track Box, Large
Max. Corr., 0.50
Guide To, Select Star, the STV will pick a star but you can pick a different one
Aggressivness (X) (in my case RA), 1.0
Aggressivness (Y) (in my case DEC), set from 0.7 to 0.3, usually 0.5
(this is what controls DEC oscillations)
Exposure To Average, I usually always attempt to set higher than 1, this is where you can control
scintillation and chasing the seeing.
Relays, all relays selected and on
I often begin a session by allowing the STV to auto calibrate and auto track.
I'll let it do 'it's thing' for a few minutes and I'll watch the track graph and see which star and what exposure it has chosen. If the correction averages are under one arc second I may just track as it is.
If the averages are higher than one arc second or the exposure is long, like over 5 seconds, or the track graph is oscillating, I will stop the tracking and reset using the full menu and try tracking again.
Again I'll watch and see how it does, if I don't like what I see I'll change the exposure, DEC aggressiveness or exposure to average value and try again.
I really appreciate your comments and suggestions.
Wade
Kent Kirkley
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