Re: Polar Alignment without Polaris (workflow)
Posted: Tue Mar 02, 2021 12:48 am
Hello Norman,
I test the script ... it works, but it is necessary that all the path are correct.
A long time, one of the "R" path was not correct ... 4.0.3 in place of 4.0.2 version. I correct it, and now it can calculate the PA errors.
Some points before ...
- it is nice that you modify the number of "dots" for the number of images during the capture. But, the plate solve takes all the images from the directory. Mean, if in the past you do 10 images, and now only 5, then the plate solve will take all. That is not good, because it could be in two different days (locations). If the new number is 5, then the plate solve has to take in account only this "new" 5 images.
- I test only in the east direction, without the air refraction selected.
- I notice during the telescope movement, that sometimes the DEC moves (it is simple to see curved line of the star during the continuous exposure)
I repeat the images capture sequence several time ... with Start Elev = 15, then the DEC moves each time. I change the Start Elev to 18, then it was OK. I think that the SynScan software commands sometimes the DEC to move a little back "v" and then in the position to finish with "^" direction.
Is it really not possible to command a RA movement alone ?
- The mount was already aligned before (the last days) first with the SkyWatcher hand controller 2-Star + Polar alignment, then with PHD2 drift method.
The results ... AZ = 0.0151° and ALT = 0.0064° ... also AZ = 0.9 arcmin and ALT = 0.4 arcmin
My initial alignment is not so bad.
I click on the "Bright Star S star sync" ... OK, it moves to a star (visible on the image), but the delta are small, the mount does not moves when I click on the "Move for ALT corr" or the other.
I remark that in SharpCap, when the plate solve result is small, the mount does not move to center the target. It is maybe a threshold in the SynScan software.
In addition I do not rely on the precision of the mount movement and/or the amount of the backlash in the axis.
A better way is to do it "on the image" after the movement and plate solve of the bright star (above step).
Like in PHD2 in the drift method ... It could be more precise in your script to have the information on the live image.
In your case, it will be not a circle ... you should calculate the position of the star depending on the camera rotation, pixel scale and pointing direction (also a lot of interesting thing to calculate )
Regards,
Jean-Francois
I test the script ... it works, but it is necessary that all the path are correct.
A long time, one of the "R" path was not correct ... 4.0.3 in place of 4.0.2 version. I correct it, and now it can calculate the PA errors.
Some points before ...
- it is nice that you modify the number of "dots" for the number of images during the capture. But, the plate solve takes all the images from the directory. Mean, if in the past you do 10 images, and now only 5, then the plate solve will take all. That is not good, because it could be in two different days (locations). If the new number is 5, then the plate solve has to take in account only this "new" 5 images.
- I test only in the east direction, without the air refraction selected.
- I notice during the telescope movement, that sometimes the DEC moves (it is simple to see curved line of the star during the continuous exposure)
I repeat the images capture sequence several time ... with Start Elev = 15, then the DEC moves each time. I change the Start Elev to 18, then it was OK. I think that the SynScan software commands sometimes the DEC to move a little back "v" and then in the position to finish with "^" direction.
Is it really not possible to command a RA movement alone ?
- The mount was already aligned before (the last days) first with the SkyWatcher hand controller 2-Star + Polar alignment, then with PHD2 drift method.
The results ... AZ = 0.0151° and ALT = 0.0064° ... also AZ = 0.9 arcmin and ALT = 0.4 arcmin
My initial alignment is not so bad.
I click on the "Bright Star S star sync" ... OK, it moves to a star (visible on the image), but the delta are small, the mount does not moves when I click on the "Move for ALT corr" or the other.
I remark that in SharpCap, when the plate solve result is small, the mount does not move to center the target. It is maybe a threshold in the SynScan software.
In addition I do not rely on the precision of the mount movement and/or the amount of the backlash in the axis.
A better way is to do it "on the image" after the movement and plate solve of the bright star (above step).
Like in PHD2 in the drift method ... It could be more precise in your script to have the information on the live image.
In your case, it will be not a circle ... you should calculate the position of the star depending on the camera rotation, pixel scale and pointing direction (also a lot of interesting thing to calculate )
Regards,
Jean-Francois