Solar Full Disk 21st Feb Baader K-Line Filter

Earls Cak Full Disk Baader Filter big file, originally uploaded by Mark Townley.

My friend in the USA, Earl Foster, was kind enough to send me the raw data for an image of the sun he took using an Meade 80mm APO refractor, Baader K-Line Filter and DMK41 camera. I am particulary interested in this filter which images with a 8nm passband in the near ultra violet. It is a cheaper alternative to the Lunt range of CaK filters, however has a much wider bandpass and hence less contrast in the image. The raw image was post processed for wavelets in Registax 5 and then final processing done in Photoshop CS4. I'm pretty pleased with the outcome, especially as the sky conditions were rather hazy when this image was taken. I hope when Earl gets some better sky conditions he will forward me somemore data for me to play around with. Thanks Earl!

Solar Full Disk 24th February 2011

Well it has been over a week since i've been able to observe the sun given the grey skies that have predominated of late.  However thursday 24th proved to be the best day for a while.  The skies were milky with some high level haze that was apparent drifting over the solar disk when looking in the eyepiece.  Over the last 10 days there have been 2 monster active regions on the sun, one of which blasted off the largest X-class flare since december 2006.  This blast was directed squarely at earth and resulted in some beautiful auroras, seen in Northern Ireland and Scotland, given their altitude in the sky, if it had been clear down here in the Midlands, there was a decent chance that from dark skies they would have been visible.

I took a number of images yesterday, including some with my new Lunt solar wedge, however the sky was very turbulent and it was only the low power full disk view that came out well.  The image below was taken with my DS40 @420mm fl with the DMK31.  This is my first mosaic image, 2 panes that were assembled in CS4.  This took some time as the poor sky transparency meant the 2 panes had differing brightnesses, however in the end I got there and now have developed a 'method' that works for me joining images in photoshop.  Ultimately I want to get the larger chipped DMK41 camera, as at this native focal length I will be able to get the full disk in one shot - much less hassle in the post processing department!



Hope you like this image anyway, the full size hi-res file can be found here - I think it does it much more justice!  Let's hope for more clear skies soon! 

Sun 11th February 2011 - Start of This Years Solar Season!

Well folks, as you can see it's been a while since I last made a post here. Infact I only managed a couple of solar observations in october, then it's been all the way through to february before I was able to view / image the sun - an unfortunate side effect of living in a built up area, my southern horizon is populated by rooftops and trees, hiding the sun from my garden in the winter months. Fortunately the sun is climbing higher and higher in the sky now as spring approaches, and as such I should be able to get more solar observing in. Certainly for now, imaging is restricted to weekends, however if I can get home from work quickly I have a opportunity for visual observation just before sunset as my western horizon is quite low.


Since last year I have had some equipment changes and additions. You can see from my previous posts the objective lens in my Coronado SM40 scope was suffering from astigmatism, which manifested itself in my images in a diagonal cross hatching pattern. This is very annoying given that the coronado scope was bought for ~£1400, I don't think i'm being unreasonable in expecting better quality given the price. However reading around it seems this is something that has been seen in other Coronado scopes. Anyway, I decided the way forward with this dilemma was to mount the etalons on another OTA. After much deliberation I finally settled on a 70mm f6 refractor, as with the cameras I had would still allow full disk imaging. I machined an adapter to fix the etalons to the tube and was ready for the sun! In addition I also purchased a Lunt Solar Wedge for whitelight observations, using my 5" refractor I am optimistic of being able to do some high resolution close up images of sunspots as we get nearer to solar maximum. I plan to write an article in the equipment section of this blog detailing all of this more.

Fast forward to today... I was only able to get a few images today due to various reasons; we had a plumber coming round to do some work, neighbours stopping by to chat as I tried to image and also intermittent fast moving cumulus cloud scudding along my southern horizon. Regardless though I persevered on and imaged away.


I attempted a 'near full disk' shot using the DS40 and DMK31 camera at f10.5, I intially thought there wasn't a huge amount to see, but after processing the image there's actually alot going on! This can be seen below...




There's something rounding the limb that was 'spitting out' plasma in the image above, so decided to zoom in to see what was goin g on. However by the time I did the activity had died down considerably, despite the images not being many minutes apart. This was taken at f19 with DS40 and DMK31...




Next I was keen to try out my new Lunt Solar Wedge. I had always struggled to image granulation with Baader film, however visually with the wedge it was really easy to see. Concentrating on Active Region 1158 I used a solar continuum filter in conjunction with the wedge and imaged at f19 using the DMK31. I was pretty pleased with the results given this is my first go with this setup, the poor seeing conditions and also the low altitude of the sun...



I'm pleased with todays results - it marks the start of the solar season for me! 9 months of observations and imaging ahead of me. With solar activity starting to ramp up this year promised to be an exciting year. Hopefully i'll be buying somemore solar equipment in the months ahead aswell.


Thanks for reading and hope you like the pics!