NGC2403, Caldwell 7 - collaboration with Gnomus

[Barry-Wilson]

This image is a fresh look at NGC2403, Caldwell 7, for me after first tackling this target 2 years ago.  This time with data gathered in collaboration with Gnomus, Steve Milne, as posted earlier this week here with his very serene rendition of this colourful galaxy floating in the void. Both of used our scopes at native FL, Steve used his Esprit 120/QSI690/Mesu200 combination to gather the luminance and I my WOFLT132/QSI683/GM1000HPS for the RGB. We set out to gather more data but were thwarted by the lousy cloudy weather the UK has had this winter.  Steve's instrument delivering a sharp and detailed luminance.

When combining the data, I also included the luminance data I shot 2 years ago using my Atik 460 on my WOFLT132 at F7 mounted on an Avalon Linear Fast Reverse. This added 3.6 hours more luminance and has helped with the detail in the core I think. I processed entirely in PixInsight, Steve using a combination of PixInsight and Photoshop.  Total data therefore for me was 12.5 hours, all in 600s subs except one of luminance from my old data (which was a mixture of 600s and 300s).  My image is a slightly different scale to Steve's having used the Atik 460 data as the master to align and rescale the subs.

Thanks Steve for the good humour and encouragement.

To help me calibrate my image I referred to a couple of the masters, Adam Block and Rob Gendler as references - http://www.caelumobservatory.com/gallery/n2403.shtml and http://www.robgendlerastropics.com/NGC2403NM.html both having quite strong blue outer spirals.

Thanks for looking.

Barry

[swag72]

Interesting to compare images taken with the same data and processed by different people...... Normally I think that your processing is really soft and subtle Barry, but here when compared to Steve's it's surprisingly 'crunchy'...... I think if I viewed this on it's own I'd have a slightly different take on it if that makes sense. I don't want to be hyper critical on such a pleasant image...... I think that for whatever reason (known to the 'processor') this has ended up as a bit of a departure from your usual style  

I hope that doesn't offend Barry - It's hard to be critical 

[ollypenrice]

I like both renditions and think they are surprisingly similar. Barry's gone for a slightly 'harder' core. (The French like to use the English workd 'hard' when discussing processing. I'm sometimes accused of beig too hard over here.) Both of you have found the blues to be on the chilly cyan side. I don't know the galaxy at all so can't comment.

But, again, the stars and background are also great and this does matter such a lot.

Olly

[Barry-Wilson]

34 minutes ago, swag72 said:

Interesting to compare images taken with the same data and processed by different people...... Normally I think that your processing is really soft and subtle Barry, but here when compared to Steve's it's surprisingly 'crunchy'...... I think if I viewed this on it's own I'd have a slightly different take on it if that makes sense. I don't want to be hyper critical on such a pleasant image...... I think that for whatever reason (known to the 'processor') this has ended up as a bit of a departure from your usual style  

I hope that doesn't offend Barry - It's hard to be critical 

I agree Sara, this galaxy has turned out more 'crunchy' than my norm.  It's good to be objective and frank - it's what we seek to help improve, deepen our knowledge etc.  So thank you.

My image has slightly more data than Steve's having added in a further 3.6 hours of luminance (and with a different ccd), so it isn't directly comparable in that sense.  In terms of processing I didn't conscioulsy push any harder, carried out more deconvolution or PI's other tools and the crunchy nature just emerged from the data.  As far as I know, Steve didn't carry out a deconvolution process - maybe that makes a difference.  It certainly helped reveal more structure within the core, one of my objectives.  I found from reading on Gendler's site NGC2403 appears to be a prominant example of a galaxy with large and extensive star forming regions, but whether this makes a difference, I'm not sure.

This image also compares to my previous version here.  As far as I can be objective about my treatment and processing of the data (not an easy task), I think the 'starker/crunchier' nature of this galaxy is in the data.

30 minutes ago, ollypenrice said:

I like both renditions and think they are surprisingly similar. Barry's gone for a slightly 'harder' core. (The French like to use the English workd 'hard' when discussing processing. I'm sometimes accused of beig too hard over here.) Both of you have found the blues to be on the chilly cyan side. I don't know the galaxy at all so can't comment.

But, again, the stars and background are also great and this does matter such a lot.

Olly

Thank you Olly.  I was certainly after detail within the core area - just wish I had a bigger scope and/or smaller pixels!

[Barry-Wilson]

Interestingly, I rotated the image to more resemble this one from Martin Pugh, APOD here, and I wonder if this alters the 'feel' of the image to which Sara was alluding?

This of course brings us to the interesting topic of presentation and its effects on the viewer . . .

[Rodd]

Nice one Barry.  Reminds me of M33.  You did not indicate whether you included Ha data--which I initially thought that you must have.  If not, you did a great job of making it look like you did.  How do you get the beautifully colored stars?.  No matter how much data I collect, my RGB stars end up being white cores with colored fringes.  

Rodd

[Barry-Wilson]

On 09/03/2017 at 12:00, Rodd said:

Nice one Barry.  Reminds me of M33.  You did not indicate whether you included Ha data--which I initially thought that you must have.  If not, you did a great job of making it look like you did.  How do you get the beautifully colored stars?.  No matter how much data I collect, my RGB stars end up being white cores with colored fringes.  

Rodd

Hi Rodd

Steve and I wanted to capture Ha but we have had a lot of very cloudy weather here in the UK, so we've found ourselves quite frustrated.

In PI I use the Repaired HSV Separation script to help repair the colour data within star cores.  You have to experiment with the settings and then apply this to the linear RGB after crop, DBE, BN and CC.  You then recombine the resultant images using the HSV option in Channel Combination - I use the 'unrepaired V' image in the last channel choice.

Barry

[Rodd]

4 minutes ago, Barry-Wilson said:

Hi Rodd

Steve and I wanted to capture Ha but we have had a lot of very cloudy weather here in the UK, so we've found ourselves quite frustrated.

In PI I use the Repaired HSV Separation script to help repair the colour data within star cores.  You have to experiment with the settings and then apply this to the linear RGB after crop, DBE, BN and CC.  You then recombine the resultant images using the HSV option in Channel Combination - I use the 'unrepaired V' image in the last channel choice.

Barry

Thanks Barry--where is that HSV script?  I don't have it under scripts. I don't think my updates and script adding features have ever worked properly. 

Rodd

[Shibby]

On 08/03/2017 at 19:42, Barry-Wilson said:

Interestingly, I rotated the image to more resemble this one from Martin Pugh, APOD here, and I wonder if this alters the 'feel' of the image to which Sara was alluding?

This of course brings us to the interesting topic of presentation and its effects on the viewer . . .

I don't know why, but my brain sees the galaxy much more as a disk this way round. I think it may be because it's more horizontal.

Nice image, by the way. The colour is so rich.

[PatrickGilliland]

Nice work Barry, the rotated version provides more depth I find.  Processing style seems purposeful but has worked.  

Paddy

[morimarty]

Thats a stunning image Barry, both you & gnomus should be very proud!

[Barry-Wilson]

Thanks Paddy, Lewis and Martyn.

18 hours ago, PatrickGilliland said:

Nice work Barry, the rotated version provides more depth I find.  Processing style seems purposeful but has worked.  

Paddy

The presentation has grown on me too.

[steppenwolf]

I think the presentation aspect of galaxies is significant for the 'viewer' - for example, to me, any rendition of M31 (Andromeda Galaxy) that doesn't look like peering into a 'bowl' just looks wrong! However, there is no right or wrong method which gives us imagers a free choice in the matter.

Either way, this is a nice image with plenty of detail and nicely processed stars.

[Barry-Wilson]

Thanks Steve.