Good Evening,
I have a Celestron 9.25 SCT mounted on their GCEM II. I currently use ASTAP for Plate Solving. I use Sharp Cap to drive cameras and drive the Mount with the Celestron CPWI where my computer is linked through the Celestron hand controller. Everytime I think I have Plate Solving figured out I have a night or two where plate solving can be almost impossible. Tonight, I struggled and tried every combination of Exposure time vs gain and spent a good 3 hours working with various sequences in different parts of the sky with no luck. What I am finding is I can use Plate Solve only and always get a solve within 10 to 15 seconds , but when I go to Plate Solve and resync the plate solve will not happen even though plate solve only does work. I just cannot figure out what in my configuration would allow a successful PLate Solve but not a Plate Solve and resync. Generally on the Plate Solve and Resync the Plate Solve will always indicate too few stars even though I previously Plate Solved only with no problem. This continues to be the part of the evening that I never know if I will ever get a solve or not. Any thoughts??
Out of Ideas in Austin
Dale Emanuel
Plate Solving Issues
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Re: Plate Solving Issues
Hi Dale,
best to send me a log, ideally with one 'worked' plate solve only and one 'failed' plate solve and sync. I can then compare what is going on and see if I can work out the cause. It would be good to have a snapshot image taken at the same camera settings too, since that lets me set things up to exactly simulate what you are doing.
The only *real* difference in the plate solving part between 'plate solve only' and 'plate solve and sync' is that the 'and sync' version tells the plate solving engine to limit the search area to within 15 degrees of the current mount position. So, if your mount co-ordinates were out by more than 15 degrees, that would explain everything ... except how the mount co-ordinates were that far out in the first place!
cheers,
Robin
best to send me a log, ideally with one 'worked' plate solve only and one 'failed' plate solve and sync. I can then compare what is going on and see if I can work out the cause. It would be good to have a snapshot image taken at the same camera settings too, since that lets me set things up to exactly simulate what you are doing.
The only *real* difference in the plate solving part between 'plate solve only' and 'plate solve and sync' is that the 'and sync' version tells the plate solving engine to limit the search area to within 15 degrees of the current mount position. So, if your mount co-ordinates were out by more than 15 degrees, that would explain everything ... except how the mount co-ordinates were that far out in the first place!
cheers,
Robin
Re: Plate Solving Issues
Thanks Robin,
Not sure how I could be over 15 degrees off. I use Sharp Cap to Polar Align and it always works like a dream. So last night I Polar aligned to an Excellent position and had CWPI move the scope to Vega. Once again the Plate solve always works within 15 seconds but the plate solve and sync is just almost a non starter on most nights. How could I be over 15 degrees off? When I finish Polar alignment, I rotate the mount back to the starting point before I order the mount to move. There has to be something strange for it to work one night the first time and then some nights it just never works. Could it be the way I return the mount to starting position and CWPI assumes it is on Polaris instead of the actual North Polar Axis?? But that is less than 15 degrees difference. I keep thinking it is something the way CWPI is working with Sharp Cap during the sync.
I will try to send you logs and pictures.
Not sure how I could be over 15 degrees off. I use Sharp Cap to Polar Align and it always works like a dream. So last night I Polar aligned to an Excellent position and had CWPI move the scope to Vega. Once again the Plate solve always works within 15 seconds but the plate solve and sync is just almost a non starter on most nights. How could I be over 15 degrees off? When I finish Polar alignment, I rotate the mount back to the starting point before I order the mount to move. There has to be something strange for it to work one night the first time and then some nights it just never works. Could it be the way I return the mount to starting position and CWPI assumes it is on Polaris instead of the actual North Polar Axis?? But that is less than 15 degrees difference. I keep thinking it is something the way CWPI is working with Sharp Cap during the sync.
I will try to send you logs and pictures.
Re: Plate Solving Issues
Which version of CWPI are you using?
Could be relevant, in that ISTR a discussion on Team Celestron about how this is handled by CWPI...
Robin, sorry, but I can't immediately recall what Derik (Celestron Engineer) said WRT this, but thought it worth raising.
Could be relevant, in that ISTR a discussion on Team Celestron about how this is handled by CWPI...
Robin, sorry, but I can't immediately recall what Derik (Celestron Engineer) said WRT this, but thought it worth raising.
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Re: Plate Solving Issues
Hi,
thanks celkins on the CPWI head's up - not something I was aware of.
Another couple of things to check are if the RA in CPWI agrees with the real pointing of the telescope and if your time zone/time/longitude are set correctly. Either of those being out could mess up the RA co-ordinate by a big margin. I suppose the acid test is to do a 'Plate solve only' and look at the co-ordinates. If they are close to the ones shown in CPWI then all is good regarding co-ordinates. If they are a long way off (more than 1 hour RA or 15 degrees dec) then the wrong co-ordinates issue may be the problem.
Anyway, logs and a captured image or two will definitely help resolve the mystery.
cheers,
Robin
thanks celkins on the CPWI head's up - not something I was aware of.
Another couple of things to check are if the RA in CPWI agrees with the real pointing of the telescope and if your time zone/time/longitude are set correctly. Either of those being out could mess up the RA co-ordinate by a big margin. I suppose the acid test is to do a 'Plate solve only' and look at the co-ordinates. If they are close to the ones shown in CPWI then all is good regarding co-ordinates. If they are a long way off (more than 1 hour RA or 15 degrees dec) then the wrong co-ordinates issue may be the problem.
Anyway, logs and a captured image or two will definitely help resolve the mystery.
cheers,
Robin
Re: Plate Solving Issues
Hello Robin,
It looks like the version of CPWI I am using is 2.3.5? I am going to try one other thing and see what happens. After getting my Polar alignment completed and returning my mount to home I am going to use CPWI to complete a one star alignment to make sure I am within the 15 degrees. In the past I just started without any alignment assuming I was close. Maybe this is not the case. I am going to give it a try on my next outing and see what happens.
Thanks for all the ideas. Bouncing this around made me realize that I still may need to have an alignment at least on one star to get in a good position for Plate Solve and Sync.
Clear skies to everyone
Dale Emanuel
It looks like the version of CPWI I am using is 2.3.5? I am going to try one other thing and see what happens. After getting my Polar alignment completed and returning my mount to home I am going to use CPWI to complete a one star alignment to make sure I am within the 15 degrees. In the past I just started without any alignment assuming I was close. Maybe this is not the case. I am going to give it a try on my next outing and see what happens.
Thanks for all the ideas. Bouncing this around made me realize that I still may need to have an alignment at least on one star to get in a good position for Plate Solve and Sync.
Clear skies to everyone
Dale Emanuel