Hi
I have found some time to experiment more with my equipment and my problem with the elongated stars.
To remind you this is my equipment
- Vixen VC200L operating at f/6.4
- SBIG ST2000xm dual chip camera
- Skywatcher HEQ5 synscan pro mount
- Skywatcher 9x50 finderscope with focal length 180mm
I have performed the following tests
test1)
point the telescope to the East - target star Vega
- take 1 sec exposure without guiding; as you can see the stars are round so this excludes problem with collimation of the telescope optics.
- start autoguiding, guiding scope is 9x50 finderscope, PHD guiding software is used
take 1 min and 2 min exposures of Vega; as you can see the stars are elongated in both images.
Please find attached the PHD logs
Also have a look at image1.JPG, this is the PHD lab output after inserting the PHD logs
test2)
point the telescope to Zenith - target star Mizar
- take 1 sec exposure without guiding; as you can see the stars are round so this excludes problem with collimation of the telescope optics.
- start autoguiding, guiding scope is 9x50 finderscope, PHD guiding software is used
take 1 min, 5 min, 10 min exposure of Mizar; as you can see the stars are almost round in all images.
Please find attached the PHD logs
Also have a look at image2.JPG, this is the PHD lab output after inserting the PHD logs
test3)
point the telescope to the East - target star Vega
- start autoguiding, guiding scope is VC200L, guiding camera is SBIG ST2000XM with dual chip ST237, MaximDL is used as a guiding software
take 2 min, 5 min, 15 min exposure of Vega; as you can see the stars are elongated in all images.
Please find attached the MaximDL logs
Also have a look at image3.JPG, this is the MaximDL graph output
test4)
point the telescope to Zenith - target star Alkaid
- start autoguiding, guiding scope is VC200L, guiding camera is SBIG ST2000XM with dual chip ST237, MaximDL is used as a guiding software
take 2 min, 15 min exposure of Alkaid; as you can see the stars are almost round in all images.
Please find attached the MaximDL logs
Also have a look at image4.JPG, this is the MaximDL graph output
You can download all the files here
http://www.albireo.gr/tmp/all.rar
So judging from these test results I have come to the conclusion that my problem can be caused by
(a) flexure by the VC200L focuser since a heavy camera SBIG ST2000xm is connected to this focuser
(b) HEQ5 mount has problem with RA motor; backlash present in RA; mount needs adjustment
I would like to hear your opinion also about my conclusion.
Thank you
Konstantinos
www.albireo.gr
Greece