Another look at M45

[ollypenrice]

Gorann's excellent RASA M45 image reminded me that my own M45 was processed before I'd thought to use the Ps Equalize function for enhancing faint contrasts, so I went back to the data for another play. This was always a somewhat head-banging image but I wanted to show how the cluster is leaving a 'wake' as it ploughs through the gas and dust of space.

(The technique involves pasting an 'equalized' copy of the image onto a layer mask, blurring it and increasing its contrasts, and then stretching through that.)

I've gone for an unconventional orientation partly to refresh my own eyes on the target, partly to put the visually 'heavier' dust at the bottom and partly to exploit two nice stellar arcs, the smaller one upper left and the larger one lower right, which trace an S shape through the picture.

LRGB from Tak 106N/Atik 11000/Mesu 200. Barking mad integration of over 25 hours.

Olly

[tomato]

Superb M45, and a great write up. How much thought do folks put into orientating their images given that we have the freedom to do this?
I think we should, it certainly works on this image, for all the reasons you have given.

[ollypenrice]

1 minute ago, tomato said:

Superb M45, and a great write up. How much thought do folks put into orientating their images given that we have the freedom to do this?
I think we should, it certainly works on this image, for all the reasons you have given.

Target-specific, I think. I do skim round the edges of any image to look at the possibilities for stellar framing. Sometimes there's something you can exploit, sometimes not. I avoid like the plague the rotating of my cameras away from orthogonality with RA and Dec, however.

Olly

[andrew s]

Fine image @ollypenrice. Is it me or has "brown" dust suddenly appeared? I don't recall seeing it until relatively recently. 

Regards Andrew 

[gorann]

Great, deep and dusty image Olly! The 25+ hours show. Did the equalize treatment make a big difference?

[ollypenrice]

9 minutes ago, andrew s said:

Fine image @ollypenrice. Is it me or has "brown" dust suddenly appeared? I don't recall seeing it until relatively recently. 

Regards Andrew 

I wonder about this. I've given the reds no preferential stretching here. Even in the shallower data sets which eventually found their way into this one I was seeing reds/browns just to the left of the cluster in this orientation, and they appear as a brownish yellow in plenty of other images. I don't think the dust is all that brown further out, though my habit of lowering the cyan components in red my tilt them that way.

After the discovery of the IFN we all started wondering about its colour so Tom and I went as deep as we could at a time when it was usually just showing as grey. We processed the data independently as a deliberate policy but both ended up with this: 

 

 

I looked for a piece on this by Rogelio Bernal Andreo, who concludes that the IFN should indeed be brown, but couldn't find it. 

And then there's the phenomenon of ERE, extended red emission, which is still unsettled amongst the professionals as I understand it.

Conclusion: I have no idea!

Olly

 

[ollypenrice]

7 minutes ago, gorann said:

Great, deep and dusty image Olly! The 25+ hours show. Did the equalize treatment make a big difference?

On the fainter stuff and its contrasts, yes.* I had been quite disappointed by these regions in the original. On the main cluster, in search of the evidence of the 'wake' through the interstellar medium, I had more success with Unsharp Masking, with the Threshold value kept high to prevent over-sharpening of small details.

Olly

* Edit. Once I had the equalized mask in place I did a further stretch in Curves but only one which lifted the lower values since these were to regions which benefitted. So a lift low down restored early to a straight line.

Edited October 19, 2020 by ollypenrice

[gorann]

Regarding the colour of the dust, it often come out as brown. There is an APOD image of M45 that is really brown, not that APODs necessarily have the "correct" colour:

https://apod.nasa.gov/apod/ap130918.html

By the way I just posted some really brownish structures nearby M45 in Taurus:

 

 

[andrew s]

Just to be clear, I was not questioning the colour balance, rather that it is now being brought to prominence.  Regards Andrew 

[Erling G-P]

Truly striking and intriguing M45 images by you and Görann Olly!

Only problem is they pretty much put one off making an attempt, as it can only end up disappointing after seeing these..