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an Atlas guiding experiment

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#1 shams42

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Posted 13 March 2011 - 12:40 AM

I've been imaging with a Meade SN6 but have thinking about moving up to a 8" f/4 Newtonian. I wasn't sure how my Atlas would handle the load, so I borrowed a similar scope from a club member. I did a 45 minute guide test with each scope back to back and did some analysis using the PhD log and a statistics package. I computed distance from the target centroid using the good old Pythagorean theorem at each log entry (sqrt of dx^2 + dy^2) and did an analysis of guide performance using that metric. Results are attached.

I'm guiding with the SSAG and 50mm finder.

You can see that the guide performance was basically identical for the 13 lb SN6 versus the ~18-20 pound 8" Newt. I also had to add another counterweight for the Newtonian, so the mount had quite a lot more weight on it in that configuration.

Seeing was poor tonight (2/5 by CSC), so absolute guide performance wasn't great.

Attached Files



#2 AstroGabe

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Posted 13 March 2011 - 01:25 PM

Very cool analysis. What analysis package are you using? The plot looks like something R would give. I've been thinking of doing something similar, but haven't had time to do it. Would you mind making your analysis script available?

#3 Jeff in Austin

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Posted 13 March 2011 - 10:34 PM

Is Distance in pixels or arcseconds? Is the top one the SN6?

Very interesting analysis. I recently moved from a 29.5 lb guide scope setup to a 22 lb OAG setup and my guiding improved incredibly, mostly due to flexure elimination. Also on the Atlas. Are you using OAG?

#4 shams42

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Posted 15 March 2011 - 09:32 AM

The top chart is the 8" f/4 Newt, the bottom is the SN6. I'm guiding with a piggybacked 50mm converted finderscope and SSAG. The distance is measured in pixels @ 5.4" / pixel.

AstroGabe, the analysis was done in SAS but I could write a R script to do this if there was sufficient interest.

#5 Gregk

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Posted 17 March 2011 - 10:02 PM

Mind posting your PHD Brain configuration numbers

#6 shams42

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Posted 17 March 2011 - 10:30 PM

RA Aggr: 85
RA Hysteresis: 15
Dec guide mode: Auto
Dec algorithm: Resist switching
Max Dec duration: 1000
Calibration step: 3000
Min motion: 15

#7 Gregk

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Posted 18 March 2011 - 12:15 AM

Thanks Taking notes .

I use a 135mm lens and a Orion SS guider here are mine
But I now have a CG-5mount

RA Aggr: 95
RA Hysteresis: 10
Dec guide mode: Auto
Dec algorithm: Resist switching
Max Dec duration: 400
Calibration step: 1600
Min motion: 15

#8 AstroGabe

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Posted 18 March 2011 - 10:51 AM

Thanks shams42, never used SAS. Would it be easy to translate to R? If there's not enough interest, perhaps you could explain to me via PM how the data was retrieved and I could write something.

#9 kw6562

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Posted 18 March 2011 - 12:25 PM

Nice analysis shams42 - I use JMP at work sometimes which I guess is part of SAS. Re: AstroGabe - This can be done in Excel also - use the FREQUENCY function to bin the data and STDEV to find the standard deviation (assuming it is a normal distribution). What is R? I'm not familiar with it...Clear skies --Keith






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