The sun at Kelling Heath (Sat 29 Mar 2014)

[MarkS]

The sun taken on Saturday afternoon at Kelling Heath.

Taken through a Lunt LS60T Ha B1200 with DMK 31AU03.AS.  A mosaic of 7 panels to get around the issue of the "sweet spot".  Each panel was 1500 frames at 1/30sec.  Stacked in AutoStakkert and post processed in Registax.  Photoshop used to assemble the mosaic and false colour added.



Larger version here:  
http://www.markshelley.co.uk/Astronomy/2014/sun29032014v3.jpg

Mark

[Marek]

Well deserved "WOW",so much detail in it! It is alive:)

[Carole]

Very nice Mark.

What method do you use to mosaic the disc onto the prominences, not had much success with that. 

Carole

[MarkS]

What method do you use to mosaic the disc onto the prominences, not had much success with that. 

I didn't do that bit in Photoshop! I did it using an image arithmetic in IRIS.

Start with the initial image showing both the solar disc with its faint prominences.
Paste a black disc to totally obscure the sun but not the outer chromosphere.  This gives the prominence image:
   
   prominence_image = initial_image with black disc

Then the solar disc image can be created by subtracting the two as follows:
   
   solar_disc_image = full_image - prominence_image

Then create a final image by adding the solar disc to a scaled up prominence image (I used a factor of 3):
   
   final_image = solar_disc_image + 3.0*prominence_image

I'm sure you could work out how to do it in PS

Mark

[Fay]

that is very good Mark!!!!!!

[JohnP]

large mage is superb Mark - can't fault it. Out of interest what was total time worked on image i.e. acquisition time and process time.. just curious how it compares with DSO's... John

[MarkS]

Hi John,

Thanks for your comment.

The acquisition time was very small: 7 panes with 90 secs of video each.
Approx 15 minutes in total, allowing for reframing between panes.

Each video clip took approx 10-12 min to stack in AutoStakkert (my desktop PC is old and slow) so that's over an hour to produce 7 TIF tiles. I did that earlier in the week.

Then last night I was solidly tinkering from 8pm until well after midnight for balancing the brightness in each pane, applying wavelet sharpening, assembling the mosaic, enhancing the prominences, remving background gradients and finally giving it false colour.  I invented techniques for each stage.  Assembling the mosiac in Photoshop was quite time consuming because I carefully selected the sharpest data in each region of overlap using layers etc.  So I would say roughly 6 hours of processing time in total.

I documented the steps as I went so next time it will be faster (maybe!).

Mark

[julian]

Very nice image Mark.