A few weeks ago I started using my C9.25 SCT telescope for solar observing. Of course I need a filter to protect eyes and gear from the enormous amount of energy this telescope is gathering (about 1200x). This filter is a Baader solar filter foil and lets about 1/1000 of the light pass through. Solar spots and granulation become visible. I posted first results with this filter earlier this month. One big disadvantage for the C9.25 though: this telescope is one big black closed tube, soaking up all the sunshine, creating thermal currents inside the tube. This air vibration ruins the quality of the image. That’s why I decided to fix the problem a few days ago. I purchased some radiator reflecting foil at the local DIY and wrapped my C9.25 with it. The difference is clearly visible (telescope and sunspots).
before…
… and after
And here you can see the first results after the modification. This picture shows Active Region AR1756 and its major sunspot. I think the difference is clearly visible (compared to my earlier post on May 3rd). I also added a picture of the Earth, relative in size. This gives you an idea of how big these sunspots really are!
Setup:
Telescope: Celestron C9.25 SCT @ f= 5900mm and Baader filter
Camera: DMK21
Mount: Mesumount 2
Guiding: none
Exposure: 256/3000 frames @ 1/312s
Date: May 25th, 2013, 10h00 UT
Location: Overijse, Belgium
Setup:
Telescope: Celestron C9.25 SCT @ f= 2350mm and Baader filter
Camera: DMK41
Mount: Mesumount 2
Guiding: none
Exposure: 128/1000 frames @ 1/1200s
Date: May 25th, 2013, 10h00 UT
Location: Overijse, Belgium
Bart Delsaert - Astrophotography 