M51 an M100 Luminance

[Rodd]

Finally, a night of good seeing.  I forgot what it was like.  I managed to capture 40 subs of M100 before it hit the treeline, then switch to M51 for 24 subs before dawn came around.  These are only luminance ayers--processed as stand alone images as strange as that sounds.  II am glad I made the decision to capture Lum instead of red, which I often start with.  Having good seeing for Lum is nice for a change.  For the M51 session, 50% of the raw subs had FWHM <2.0...1.6-1.8, which is very unusual for me, especially with 300 sec luminance subs.  I am really looking forward to continuing these projects.

I may have pushed things a bit for these images...just trying to see how much the data would give me.  I know I need more data, but for 3 hours and 2 hours, I am encouraged.

TOA 130 and ASI 1600

M51: 24 300 sec subs-Probably a bit bright.  I m always harping on reducing brightness with M51 and it seems I still have a way to go.

M100: 40 300 sec subs

 

Edited April 21, 2020 by Rodd

[Rodd]

Hers a center crop of M51--cropped and gradient removal--no other procssing except noise removal in background to allow me to drop the black point.  My sky is pretty bad even at the best of times and the background space is typically more gray than black with luminance--foring me to work a bit to achieve a respectable background.  The galaxy has not been touched.  Note the bright, core with no detail--brightness steals structure, which is apparent in my more heavilly processed image above.  That is why maintaining a wide dynamic range in M51 requires a leash be put on brightness.  I know most people are wondering why I would bother poting a couple hours of luminance.  Becuase for me, I typically need 8-10 hours of luminance to achieve similar results.  The fWHM of the unprocessed stack is 1.9 arcsec/pix.  The FWHM of the cropped image is 2.7 arcsec/pix.  I have to enjoy this while I can.

 

Edited April 21, 2020 by Rodd

[peter shah]

Wow what a lovely set of images.....beautiful detail

[Rodd]

6 minutes ago, peter shah said:

Wow what a lovely set of images.....beautiful detail

Thanks Peter.  And the degradation begins.  I added data last night but conditions were not as good as the first night (and they probably wont be again for untold months).  In the end I am afraid it will be one long, downhill ride!  At least now I can really appreciate good seeing (and this was only 3/5 supposedly).  I can only imagine what 5/5 at a dark site would be like.

[peter shah]

35 minutes ago, Rodd said:

Thanks Peter.  And the degradation begins.  I added data last night but conditions were not as good as the first night (and they probably wont be again for untold months).  In the end I am afraid it will be one long, downhill ride!  At least now I can really appreciate good seeing (and this was only 3/5 supposedly).  I can only imagine what 5/5 at a dark site would be like.

I havent done much over the past months .....but I did do some visual over these clear spells the views of M51 were just spectacular.

[alan potts]

Stunning detail in those two Rodd, are you going to add colour, two great captures,

Alan

[Rodd]

2 minutes ago, alan potts said:

Stunning detail in those two Rodd, are you going to add colour, two great captures,

Alan

Thanks Alan--yes I plan to.  I am still collecting Lum.  I added a couple hours each last night and if all goes well will add a few more hours tonight.  Ideally I would like 10 hours of lum per image--but will probably have to accept about 8...otherwise its noisy with a difficult background.  Until I figure out what it is that I am missing (probably in processing--but you never know, could be acquisition) I have to collect a lot of data.  I just hope the seeing stays good throughout these two shoots

[Rodd]

2 hours ago, peter shah said:

I havent done much over the past months .....but I did do some visual over these clear spells the views of M51 were just spectacular.

Always enjoy your masterpieces

[Rodd]

I think I am done with the lum for M100.  In total I am using 96 300 sec subs for an 8 hour stack.  Noy the 10 hours I wanted, but conditions get a little worse every night.   The FWHM of the stack has gone from 2.0 to 2.15 to 2.3.  Not too bad an increase for the addition of more than double the data.  But I don't want to degrade it any more.  The extensions are now portrayed fairly well--at least for an insertion as a lum

So this is basically the Lum I will insert into the HaRGB image--though I will probably deconvolve the piral arms for fine scale sharpening.  I did not deconvolve here, yet.   I am also thinking of capturing a coup,e of hours worth of 20 sec subs to try and decrease the brightness of the core.  Its not overexposed--well, its right at teh edge.  Reducing the brightness using curves of other tools is not the most effective.  I figure maye 1 hour of 20 sec subs migt do the trick.   We'll see how the RG B image comes out--it may be that this version is too bright.  For now its a stand alone.....off to try deconvolution on the spiral arms.

 

[Rodd]

Here is 96 300 sec subs with deconvolution inlinear state to sharpen core details--and spiral arms.  This is the lum for insertion

 

Edited April 23, 2020 by Rodd

[Rodd]

nope--my linear stack looks great--i botch the stand alone images.  I'll wait for a full data set to tinker any more.  maybe I need even more data