Double Stacked CaK Disk - 29th September

My newly constructed double stacked CaK filter is showing itself as a keeper.  Compared to a single stack CaK unit the plage is much brighter compared to the background disk and super granulation is much more evident and apparent over the entire disk.  More interestingly is that proms are much more apparent than in the single stack filter.  Today a surge prom in the 2 o'clock position was easily see, even in this image taken with the 40mm at f20.  There are tantalising hints of the spicule layer also being visible.  Given that this shot  was taken in poor seeing conditions with a low altitude sun, it does bode for even better results when conditions are ideal.  There is still work to do; a 'ghost' is visible superimposed on the right hand side of the disk, but this should be relatively easy to either remove or throw out of the field of view.  In short, i'm really pleased with this filter, I just wish I had got it 6 months earlier this year!

ar11850 & Surge Prom - DS CaK 29th September

ar11850 CaK, a photo by Mark Townley on Flickr.

There was a lovely surge prom visible today using the double stacked CaK filter. The faint CaK spicule line can also just about be seen on the limb. It seems that double stacking in CaK makes the prominences much easier to see compared to the single stack images. I was pushing things today with the low altitude sun, with this shot being taken with the 100mm at 2000mm focal length with the DMK31 camera, but this image is just about usable... It definitely has much promise for when the sun is higher in the sky.

ar11850 & ar11846 DS CaK 29th september

ar11850 ar11846 caK, a photo by Mark Townley on Flickr.

A medium scale shot of the departing active regions visible on the suns disk today taken with the 100mm at 1000mm focal length with the DMk31 camera.

Ha Full Disk - 29th September

The sun may not have many large active regions at the moment, but the disk is far from being bland.  Lots of filaments are visible in this image taken with the Coronado DS40 at f20 with the DMK31 camera.

CaK Full Disk 22nd September

ds cak full disk colour, a photo by Mark Townley on Flickr.

Even on a relatively quiet day on the Sun as it was as we passed into autumn there is still plenty to see in CaK wavelengths. This was another outing for the double stack CaK filter, which had been redesigned in its configuration to remove the reflections and ghost images that were present when i first set it up. It is performing very well now with only minimal ghosting at the bottom of the disk which should be fairly easy to remove with a bit of tilting. This was taken with the 40mm @ f20 with the DMK31 camera.

Ha Full Disk - 22nd September

DS Ha full disk bw, a photo by Mark Townley on Flickr.

Some intermittent september sunshine allowed me to shoot this full disk using the DS40 at f20 with the DMK31 camera.

DS CaK Full Disk 'vs' Solar Dynamics Observatory AIA1700 - 21st September

The above shot was taken with my very recently constructed 'double stacked' filter; this is a concept i've been wanting to realise for sometime now.  Commercial CaK filters have a bandpass of >2.2a, however by stacking 2 of these together in series it should be possible to reduce the bandpass down to 1.5a.  This is well within the performance of many professional observatories world wide and with it should bring advantages over the commercial units.  Yes, there will be a reduction in the through pass of light but this is easy to address with an alternative choice of ERF, however the pluses out weigh this; reduced bandpass means an improved signal to noise ratio for the image, and with it super granulation cells are much easier to see, while still faint prominences and filaments are also easier to see than in commercial form.  Plage areas appear much brighter than usual, and the non active disk is much darker.  

When I looked at the monochrome version of this image I was struck at how much it resembled the images the Solar Dynamics Observatory Atmospheric Imaging Assembly (AIA)1700 camera.  So much so I decided to colour the above image with their palate and do a direct comparison; the image below was taken by the SDO at the same time I took the image above.

Comparing the 2 images directly I don't think the double stack CaK filter is performing too bad, especially when you compare the 2 imaging systems:

The Solar Dynamics Observatory is a NASA mission that was developed by the Goddard Space Flight Institute that sits in orbit above Earth taking photographs of our star at an estimated cost of 817 million USD. 

The double stacked CaK system was developed by me and sits on Earth looking through 300 miles of atmosphere and the optical system for this cost less than 1000 GBP.

When taken in comparison like this, I think the double stack CaK system has a lot to offer and will offer great images for a lot longer than the estimated 5 year life time of the Solar Dynamics Observatory.

Below is my monochrome version of the image which is also very comparable in detail to that of the Paris Meudon Observatory seen below it.