Thor's Helmet HaOIIIRGB

[Petergoodhew]

My first attempt at this a year ago was pretty awful, so I've captured more data and reprocessed from scratch. All capture on the TMB in Spain.

[ollypenrice]

That's a feisty rendition of the nebula but the stars seem to be struggling. Are you rock solid on focus? Mind you, the recent and strange weather has sent us diabolical seeing here in SE France. My robotic Italians working at long FL are temporarily stymied. Could that be affecting you as well? The red channel seems to be particularly hit.

What filters/channels combination do you show us here, Peter?

Olly

[Petergoodhew]

14 minutes ago, ollypenrice said:

That's a feisty rendition of the nebula but the stars seem to be struggling. Are you rock solid on focus? Mind you, the recent and strange weather has sent us diabolical seeing here in SE France. My robotic Italians working at long FL are temporarily stymied. Could that be affecting you as well? The red channel seems to be particularly hit.

What filters/channels combination do you show us here, Peter?

Olly

Thanks Olly. Yes the focus was rock solid, the problem is a result of my clumsy processing - a combination of attempting to combine RGB stars with Ha and OIII stars, not helped by some of the frames coming from a year ago being about 40% out of alignment with the other frames. I'll take a relook at this.

Ha was combined with Red, OIII combined with both Green and Blue.  Astrodon filters.  5nm Ha and 3nm OIII.

Off to redo this homework!

[ollypenrice]

51 minutes ago, Petergoodhew said:

Thanks Olly. Yes the focus was rock solid, the problem is a result of my clumsy processing - a combination of attempting to combine RGB stars with Ha and OIII stars, not helped by some of the frames coming from a year ago being about 40% out of alignment with the other frames. I'll take a relook at this.

Ha was combined with Red, OIII combined with both Green and Blue.  Astrodon filters.  5nm Ha and 3nm OIII.

Off to redo this homework!

Hmmm, the Astrodons shouldn't really affect the RGB stars at all, being so much smaller. What do the red stars look like?

Olly

[Petergoodhew]

22 minutes ago, ollypenrice said:

What do the red stars look like?

This was the initial rgb data before any processing. i can see now that I failed to protect the stars when stretching, and this has resulted in them getting fatter.

[ollypenrice]

What's odd is that the Ha is affecting them when combined. Really it shouldn't do so, especially with tiny Astrodon stars. Not sure what to suggest.

Olly

[Petergoodhew]

15 minutes ago, ollypenrice said:

Not sure what to suggest.

Thanks Olly.  I'm pretty sure the Ha is innocent, and it's a result of processing errors.  I'm going back through the processing step by step to see what caused the stars to get bigger. I have this dreadful tendency to concentrate on processing the nebula or galaxy and neglect what happens to the stars. I'm pretty sure that I will get it sorted. Will resubmit my homework for marking.

[Hallingskies]

I think the first image is just great.  I'd be well pleased to get a result like that! 

[Petergoodhew]

On 2/26/2018 at 11:04, ollypenrice said:

Not sure what to suggest.

The mystery is solved Olly.  As suspected it was me, and not Astrodon at fault. The cause was a star mask that wasn't fully covering the larger stars, resulting in their outer regions getting stretched.  I do struggle a lot with getting the right mask, especially with significant variance in star sizes (something to cover on my visit to Les Granges in a few weeks perhaps).  I have to confess that there was also one stretch where I forgot to apply a star mask, which obviously didn't help at all.  Furthermore I had used the wrong luminance frame too, which is now corrected as has brought out much more nebulosity. Anyway, here's my reworked homework for marking!

[Petergoodhew]

17 hours ago, Hallingskies said:

I think the first image is just great.  I'd be well pleased to get a result like that! 

Thanks. It's one of my favourite targets - very attractive and very unusual.  Adding narrowband to the channels makes a huge difference.

[ollypenrice]

Oh wow, now you're talking. That's a very exciting rendition with both nebula and stars vastly improved.

Olly

 

[carastro]

Love it.

Carole

[gorann]

Beatiful!

Very nice detail on the helmet and a 3D feeling to the whole creature (or whatever it is). I think that is what earth bound photographers call bouquet with some parts being sharp and others appear to be in front or behind the focal plane, but in this case it must be an illusion of course.

[Petergoodhew]

17 minutes ago, gorann said:

Beatiful!

Very nice detail on the helmet and a 3D feeling to the whole creature (or whatever it is). I think that is what earth bound photographers call bouquet with some parts being sharp and others appear to be in front or behind the focal plane, but in this case it must be an illusion of course.

Thanks Göran.  Some people deliberately make some areas sharper than others to create a 3-dimensional feel. I didn't - it's the target itself that has this amazing contrast between sharp detail and fuzzy nebulosity. It's a very intriguing target. It's obviously well known for its resemblance to Thor's Helmet, but if you rotate it 180 degrees it looks to me more like a menacing giant one-eyed alien bug!

[ampleamp]

That second version is very good Pete; excellent! Your holiday has done you good 

[peter shah]

It just gets better and better as you go along nice to see it progress

[Demonperformer]

14 hours ago, Petergoodhew said:

if you rotate it 180 degrees it looks to me more like a menacing giant one-eyed alien bug

I see what you mean. But my first impression on seeing the image at the top was of a ballet dancer from above, facing towards the top of the picture. Her left foot is on the ground, her right leg is horizontal, behind and she is swinging it round to the right, and her arms are stretched upwards. Although she does have funny, rather teddy bear like, ears! So I don't see the name 'ballet dancer nebula' catching on ...