Strange Bedfellows - IC 4628 & NGC 6231 in Ha

[Andy01 (Andy)]

Strange bedfellows indeed.

This pair of objects are linked by clouds of Ha, but appear as wildly differing shapes with a cometary globule at the top and the famous Prawn below.

Two panel mosaic with the bottom data captured almost exactly a year ago and the top captured last night under (and almost next to) a full moon resulting in another trip to gradient city.

Average seeing & some thin cloud meant the two data sets are a challenge to process as one.

I plan to eventually add RGB to this but not until under a dark sky again!
Also tempted to add another panel or two to the right to include the infamous WOLF'S HEAD nebula.

Approx 6 hrs per panel, 30min subs Astrodon 3nm Ha
Captured from suburban Melbourne.

Big one HERE

[multiweb (Marc)]

Hi Andy, pretty deep stuff.Love the depth and neb you've got. If possibe I'd watch out for the stellar profiles. Easy to burn in Ha with long subs and you get sequins but unfortunately you can't do much about it if you're already over the well in your data, otherwise you can fix it during processing.

If you plan on the wolf head be ready for another two panels at least. One won't cut it.

[LewisM]

Loving it.

[Placidus (Mike and Trish)]

Beautifully moody, evocative composition Andy. The two images have combined very well despite the very difficult moonlit thin cloud.

Reckon it would be worth tracking down what went wrong with the star profiles and reprocessing from that point. One guess would be wrapping beyond 65535 (white wraps to black), when sharpening perhaps. Should be easy to spot exactly when it happened.

The dark tower looks like a lighthouse with a collimated beam of light. Perhaps it is something more sinister and dangerous.

Ripper photo.

[RickS (Rick)]

A cool field, Andy. I have a Ha framework for a mosaic of this area including the Wolf's Head as well from last year and hope to complete it in 2017, but it will depend on the weather and work commitments...

[Andy01 (Andy)]

Originally Posted by multiweb

Hi Andy, pretty deep stuff.Love the depth and neb you've got. If possibe I'd watch out for the stellar profiles. Easy to burn in Ha with long subs and you get sequins but unfotunately you can't do much about it if you're already over the well in your data, otherwise you can fix it during processing.

If you plan on the wolf head be ready for another two panels at least. One won't cut it.

Merci Marc yes 4 panels are required, might wait until the moon disappears though, these gradients are a pain to process for mosaics!

Originally Posted by LewisM

Loving it.

Onya Lewis, cheers

Originally Posted by Placidus

Beautifully moody, evocative composition Andy. The two images have combined very well despite the very difficult moonlit thin cloud.

Reckon it would be worth tracking down what went wrong with the star profiles and reprocessing from that point. One guess would be wrapping beyond 65535 (white wraps to black), when sharpening perhaps. Should be easy to spot exactly when it happened.

The dark tower looks like a lighthouse with a collimated beam of light. Perhaps it is something more sinister and dangerous.

Ripper photo.

Cheers M&T
It's wierd this pair, almost like Jeckyl & Hyde- on reflection last years data was shot under a newish moon, with a 5nm Ha filter. This set was with a 3nm filter under a Hunter's moon.
Madness to try to balance the data, which is why I think they are quite different in appearance. I tried very hard to balance them but obviously lost the star details in the process.
It's not a deal breaker as I'll likely remove/minimise them when I add the RGB, and the constructive critique from you & Marc is noted & appreciated!
Might try something different tonight if it stays clear

[multiweb (Marc)]

Originally Posted by Andy01

Madness to try to balance the data, which is why I think they are quite different in appearance. I tried very hard to balance them but obviously lost the star details in the process.

When doing mosaics in moonlight flatfielding and calibration become critical. Make a star mask to leave the stars alone when doing deconvolution or use a program that does that well such as startools. Save your starmask as a 16bit TIFF so you can reuse it in PS or PI. In PS gradient xterminator does a good job at flattening remaining gradients. But if you start with well calibrated panels close enough to each others in term of illumination then PS won't have any problem blending in the seams. Just before blending you can also tweak contrast/brightness between panels to match them closely, then collapse and blend.

[topheart]

Very interesting composition Andy......Great potential when other data added in!!
Cheers,
Tim

[Atmos (Colin)]

Looks great Andy! As has been mentioned, some of the larger stars have gone a bit askew. I am assuming that you did some contrast enhancement? If so, it may be a star mask issue.

For people more in the know (or you release some RGB tonight!!!!), a lot of the nebulosity on the top looks like millions of partially resolved stars. Is this an artefact (NR) or just LOTS of stars?

[SimmoW (SIMON)]

Nice and different Andy. Will be good to see the other filters if they work out.

Mike might chime in, but the Decon detector app on my phone (only available for Android) has just maxed out .

[marc4darkskies (Marcus)]

Originally Posted by Andy01

Strange bedfellows indeed.

This pair of objects are linked by clouds of Ha, but appear as wildly differing shapes with a cometary globule at the top and the famous Prawn below. ...

Looking really good so far Andy!

Originally Posted by Andy01

...
Also tempted to add another panel or two to the right to include the infamous WOLF'S HEAD nebula.

That's not what that nebula is called Andy!

Look forward to seeing your rendition though!

[gregbradley]

Originally Posted by Andy01

Strange bedfellows indeed.

This pair of objects are linked by clouds of Ha, but appear as wildly differing shapes with a cometary globule at the top and the famous Prawn below.

Two panel mosaic with the bottom data captured almost exactly a year ago and the top captured last night under (and almost next to) a full moon resulting in another trip to gradient city.

Average seeing & some thin cloud meant the two data sets are a challenge to process as one.

I plan to eventually add RGB to this but not until under a dark sky again!
Also tempted to add another panel or two to the right to include the infamous WOLF'S HEAD nebula.

Approx 6 hrs per panel, 30min subs Astrodon 3nm Ha
Captured from suburban Melbourne.

Big one HERE

Nice one Andy. I also have some widefield data for the Dark Tower. You've caught that wider area of Ha around it nicely. I hadn't seen that before. My data is not as wide field as yours.

Greg.

[strongmanmike (Michael)]

As you seem to be aware of, some relatively minor technical issues to sort to make it really shine, sure, but overall and viewed at the standard size when opening in Astro Bin, t'is a really great vista of two objects rarely imaged as a pair, well done. The final product should really look rather nice, especially if you try keeping to the more natural processing/colour approach you showed in your SH2-12 piece

Mike

[Andy01 (Andy)]

Originally Posted by multiweb

When doing mosaics in moonlight flatfielding and calibration become critical. Make a star mask to leave the stars alone when doing deconvolution or use a program that does that well such as startools. Save your starmask as a 16bit TIFF so you can reuse it in PS or PI. In PS gradient xterminator does a good job at flattening remaining gradients. But if you start with well calibrated panels close enough to each others in term of illumination then PS won't have any problem blending in the seams. Just before blending you can also tweak contrast/brightness between panels to match them closely, then collapse and blend.

That's good advice thanks Marc!

I like the idea of making a mask in Startools and saving it for use in PS - I'm going to try that one out as I've not yet found a really nice starmask technique for PS.

As to successfully blending these two - well, for a more consistent result, I think it's a reshoot of the top half under a new moon

Thanks for all the tips too

Originally Posted by topheart

Very interesting composition Andy......Great potential when other data added in!!
Cheers,
Tim

Cheers Tim, I'll try not to dissappoint you lol

Originally Posted by Atmos

Looks great Andy! As has been mentioned, some of the larger stars have gone a bit askew. I am assuming that you did some contrast enhancement? If so, it may be a star mask issue.

For people more in the know (or you release some RGB tonight!!!!), a lot of the nebulosity on the top looks like millions of partially resolved stars. Is this an artefact (NR) or just LOTS of stars?

Hey Colin, I probably punished the data too much getting the moonlight gradients out - maybe I need to go back & revisit the basics of stretching mosaics under mixed conditions.

As to the nebulosity - here is a great image by Paul Haese that may better answer your question.

Originally Posted by SimmoW

Nice and different Andy. Will be good to see the other filters if they work out.

Mike might chime in, but the Decon detector app on my phone (only available for Android) has just maxed out .

Cheers Simmo, RGB will have to wait until the planets align again - ie: new moon, clear skies, leave pass + free weekend.

Don't think I used decon as such, but probably overdid one of the other techniques used.

Originally Posted by marc4darkskies

Looking really good so far Andy!
That's not what that nebula is called Andy!
Look forward to seeing your rendition though!

Cheers Marcus, Not sure of it's exact name but Wolf's Head has a nice ring to it - Think it may have been christened that by Paul Haese

Originally Posted by gregbradley

Nice one Andy. I also have some widefield data for the Dark Tower. You've caught that wider area of Ha around it nicely. I hadn't seen that before. My data is not as wide field as yours.

Greg.

Cheers Greg, yes I agree it's a very interesting region with lots going on - looks quite stormy in fact - I couldn't find many similar compositions on the web for reference but there is one here fyi

Originally Posted by strongmanmike

As you seem to be aware of, some relatively minor technical issues to sort to make it really shine, sure, but overall and viewed at the standard size when opening in Astro Bin, t'is a really great vista of two objects rarely imaged as a pair, well done. The final product should really look rather nice, especially if you try keeping to the more natural processing/colour approach you showed in your SH2-12 piece

Mike

Thanks Mike, I appreciate the positive feedback
I'll try to keep the Andyfication low and the natural look high!

As mentioned above, it might take a while for the opportunity to present itself again to go full HaRGB mosaic, but fortunately these objects arn't going anywhere anytime soon! - (and I've since found another rarely imaged gem that I want to attempt)