Sunday 29 January 2012

Ha Full Disk - 28th January (Flats and Smart Sharpen)

full disk colour 2 by Mark Townley
full disk colour 2, a photo by Mark Townley on Flickr.

There are days when what you see through the eyepeice and what is seen on the camera preview screen just doesn't equate with what comes out of the software at the end, and saturday was one of those days! The suns limb could be seen to have rolling waves sloshing around it's limb, and I nearly didn't bother to image for this reason, i'm glad I did because this is one of the best image i've got in weeks!

I've been using the unfocussed flat for some time now on my solar images, sometimes with good results, sometimes not so good. Something I now believe is fundamentally crucial to their effectiveness is that the flat needs to be taken exactly mid disk to avoid any gradients or banding in the resultant images. When making a mosaic such as this image which is composed of 6 panes, gradients can wreak havoc in uneven illumination of the final composition. So, if you're using flats with your solar images make sure they're taken dead centre of the disk!

This is my very first image made using the smart sharpen technique instead of wavelets. Recently on Stephen Ramsdens excellent forum (link opposite) professional astrophotographers Chris Schur and Ken Crawford have been advocating the use of an iterative approach with the unsharp mask and smart sharpen functions in Photoshop as opposed to using wavelets in registax. As you are probably aware wavelets are a invaluable tool used by many in numerous forms of astronomical imaging, however they do have a nasty side effect if used over zealouslly; they often produce a halo effect around features such as prominences. It has taken me some considerable time to find a setting I am happy with in terms of results - this seems to be dependant on a number of factors including the focal length the system is working at, pixel size of the sensor, and to a certain extent how the luminosity is spread out through the 'curve' of the image. However the results are very positive - the finer detail on the sun seems much easier to see, giving it a hairy or fluffy like appearance.

Hopefully the high pressure that is over the UK at the moment will hold and I will be able to image again next weekend. The sun is slowly but surely getting higher in the sky now and shouldn't be too much longer when my viewing window extends enough to allow me to image at a variety of wavelengths and a range of image scales!

Tuesday 17 January 2012

Fiery Solar Start to 2012

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

Chilly and clear winter days have given a great start in terms of solar observation for 2012. The sun has certainly not failed in delivering plenty for us to see - sunspots, active regions, filaments, flares and filaproms. The start of a good year for solar!

Sunday 15 January 2012

WL Spots - 15th January

WL Spots by Mark Townley
WL Spots, a photo by Mark Townley on Flickr.

Ok, these are never going to win any competitions but had just enough time today to grab some white light shots. This was taken with the baader solar continuum filter in conjunction with an IR cut filter. The initial gamma on the DMK was set rather higher than I liked on reflection, but this gives a reasonable view of the smittering of small spots the cover the northern hemisphere of the sun at the moment.

Taken with 70mm frac @ f12 DMK31

CaK Full Disk - 15th January

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

I was able to utilise every minute of todays short viewing window, and after running off the Ha shots I decided to have a go at CaK wavelengths; poor seeing left me none too optimistic about what would come out, but with this in mind i'm really pleased with this result. The boiling limb caused by poor seeing shows itself on the final image as a rough edge, and can be seen easier when viewing the full size image. I did have a go at some white light shots, but the fine granulation was destroyed by the turbulent seeing.

Either way, i'm really happy with the amount of solar imaging i've been able to get in so far in 2012. Let's just hope the weather carries on obliging and lets me get many more sessions in!

Ha Full Disk - 15th January

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

Another clear day again this sunday, albeit with a bit of high cloud that made for interesting results when I applied the flat to the image giving an uneven frame. However this has been removed as much as possible in post processing... Lots of lovely detail visible today - great filaments! These seem aplenty on the solar disk of late...

Ha Full Disk - 14th January

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

Wintertime high pressure is sat squarely over the UK at the moment, and with it comes deep blue skies and cold temperatures. This is great for solar observing, however on my local horizon the sun only gets about 6 or 7 degrees altitude above it - the downside of this is poor seeing, this is most notable in solar images on the limb. which appears to dance and wave in the atmospheric instability. From an imaging point of view this renders (at this resolution!) the spicules and proms on the limb invisible when doing a one shot. However I really took my time in getting a good flat and this has paid dividends in eeking out as much disk detail as possible. Taken with the DS40 @ f21, DMK31.

Saturday 7 January 2012

Proms! 7th January 2012

proms by Mark Townley
proms, a photo by Mark Townley on Flickr.

Some of the best proms i've seen for a while were visible this morning. This was taken with the DS40 @ f26, DMK31. Actually very good seeing for such a low altitude sun...

Filaprom - 7th January 2012

filaprom by Mark Townley
filaprom, a photo by Mark Townley on Flickr.

One of the best filaproms i've seen for a while! Taken with DS40, 2.5x powermate - f26 DMK31.

Hydrogen Alpha Full Disk - 7th Janury 2012

full disk by Mark Townley
full disk, a photo by Mark Townley on Flickr.

An unexpected blue sky this morning allowed me to get some imaging in: absolutely loads going on! Filaproms, proms, filaments and flares! Slightly overexposed on the flaring regions but atleast this shows up the proms a bit better! Taken with the DS40 @ f21, DMK31.

Tuesday 3 January 2012

First Sun of the New Year!

full disk1 by Mark Townley
full disk1, a photo by Mark Townley on Flickr.

I've really lucky this year to get as many images in as I have, though this has been helped by a neighbour who considerably cut down a tree that had been a blot on my southern horizon. This has given me a daily hour long window in the winter months to observe and image the sun.

As we start in 2012 the sun is showing plenty of activity as we approach solar max (even if it is a weak solar max!). There are filaments galore on todays disk, with the southern hemisphere being dominated by behemoth AR1389.

This is the first shot taken with my recently modded DS40 scope, more details can be found about this on Stephen Ramsdens excellent solar forum...

Late December Sunshine!

full disk by Mark Townley
full disk, a photo by Mark Townley on Flickr.

With only a few days to go until the solstice I was really surprised to get my last image of 2011 in!