Following my recent post about the error message ‘something terrible has happened’, there were several very useful posts and I have been able to study, understand and implement them. First clear evening for days so I had the SGP sequences set up in advance. After focusing and ‘centre here’ (which didn’t seem to work well for me) I went ahead and ran a sequence of four targets. Perfection. Each target centred to within 100 pixels (my test settting) and watched; usually two attempts were all that was needed to place the target within ~10 pixels, so all the images were excellent - except for me having to pause during a cloud break, and the pause worked 100% as well. I can therefore reduce the 100 pixels.
The next challenge will be to incorporate dither especially when using large number of images.
One or two minor puzzles arose; during centring the slews appeared to be too fast. I shall try to find a slower setting - but it did all work.
More success like this please
Lawrence Harris
PS any chance of peaking at the SGP 3 manual without commitment?
Lawrence, glad to hear you are getting good results. Do you happen to know what specific or combination of changes you made to get rid of the failure to centre? The reason I ask is that I have just upgraded from CGX to CGX-L and while the CGX would centre to within 20 pixels on the first or second attempt the CGX-L will always centre with an RA error of 100 to 105 pixels (DEC is fine <10 pixels). Even if I nudge the target to be spot-on, when I centre it pushes the RA to 100 off. All settings are, I think, the same as they were for the CGX.
The main parameter change was the number of attempts allowed for
centering was increased from 1 to 4. The log files show a fairly
consistent second attempt which gets very close anyway. In addition,
this should be irrelevant, I powered up the scope (Celestron) and
selected ‘simple align’ (someone’s suggestion) which uses logical data
(time, lat+long etc) instead of actually using the last good alignment.
Also, I don’t yet follow where the Julian date is set (noticing that
they are clearly not set for current epoch).
Thanks for that. However, I always have 4 attempts as my normal centring routine and now I’m finding that if the first pass shows RA of, say, 60 pixels (which shows Failed as I have the criteria set at <30 pixels), then the second, third and fourth attempts are something like 103, 105, 99. The DEC always comes in nicely on the second attempt and remains good for the third and fourth. This is happening whether I use ‘last alignment’ or ‘quick alignment’, with scope set to sync or none. I’m not expert on the logs but will have to try and read them. It’s as though there is a pre-set 100 pixel error being introduced. Ho hum.
