SH2-240: Spaghetti nebula mosaic WIP

[Pompey Monkey]

I had this daft idea while I was at Olly's a few weeks back - A mosaic of the stupidly faint SH2-240 from the murky sea-side near Portsmouth.

I did attempt to fit a 0.79 reducer to my Esprit, but by the time the spacing was sufficient to get round stars, I couldn't reach focus! This reducer would have enabled me to do a four panel image. Alas, now it will be six

I'm starting in Ha and plan to add OIII and RGB stars at some point. I think this is going to be an all winter project, even with my newly acquired 3 nm NB filters by Chroma.

I managed five hours last night before my PC inexplicably, but gracefully, shut itself down at 4 am. The result is 20 mins on one panel, 40 on another and 1 hour each for the other four. 

This is also the first time I've tried a big mosaic and I'm using MosaicByCoordinates and GradientMergeMosaic in PI. Given the paucity of my data, I think that the merge has gone quite well, although there are some funny artefacts around some bright stars on the joins.

At least it's a start, and I attach a full-size (albeit JPG) of my progress. At least it's visible!

[ollypenrice]

Good going, Paul. This is a Royal (nay Imperial!) devil of a target, being too big and too faint to qualify as even slightly reasonable. At only 500mm with a full frame you can't do it justice in two panels yet, when it's done, it looks as if it ought to be quite small. Not fair! I've only done it in a camera lens.

Please keep going. There is a reason why we don't see many renditions.

Olly

[Pompey Monkey]

36 minutes ago, ollypenrice said:

Good going, Paul. This is a Royal (nay Imperial!) devil of a target, being too big and too faint to qualify as even slightly reasonable. At only 500mm with a full frame you can't do it justice in two panels yet, when it's done, it looks as if it ought to be quite small. Not fair! I've only done it in a camera lens.

Please keep going. There is a reason why we don't see many renditions.

Olly

Thanks Olly,

It's not often done at a resolution to do it justice*, again, because of its angular size. I think (hope) that there is some really delicate lacework going on in there to justify the effort. I have to say that my new Ha filter is really doing the job even with the moon laughing at me, seemingly every time that the clouds part....  

*This is my rationalisation**, and I'm sticking to it

**That is, I cannot possibly afford to buy a Tak and large format CCD....lol

 

[Barry-Wilson]

Like Olly, I encourage you to persevere.  It is a spectacular target and you will be rightly rewarded if weather allows you to collect the data.

You have a super start Paul and fingers crossed for the weather.

[wimvb]

That's a great start. Looking forward to the final image. Let's hope the weather plays nice.

The edge artefacts can be cleaned up if you adjust the feather radius of GradientMergeMosaic.

[don4l]

That is a good start.  It is a very rewarding target.

 

Have you noticed the very faint patch just right of centre at the very top?  Does anyone know what this is?

 

 

[Pompey Monkey]

20 minutes ago, don4l said:

That is a good start.  It is a very rewarding target.

 

Have you noticed the very faint patch just right of centre at the very top?  Does anyone know what this is?

 

 

This one?

Good question!

[don4l]

That's the one.  I've noticed it in my data and was wondering if it was an artifact.  I haven't been able to identify it - although I haven't looked too hard.

 

 

[wxsatuser]

Looking good and worth a go but lots of exposure needed.

Attempted here with the Samyang 135mm @ f/2, with the near full moon and was surprised at what popped out with all the LP.

There is a lot of even fainter stuff nearby which most images do not show, it's a rich region that loves very long subs.

[Pompey Monkey]

1 hour ago, wxsatuser said:

Looking good and worth a go but lots of exposure needed.

Attempted here with the Samyang 135mm @ f/2, with the near full moon and was surprised at what popped out with all the LP.

There is a lot of even fainter stuff nearby which most images do not show, it's a rich region that loves very long subs.

I want to go deep, and I know there's a lot of dusty stuff in the region too but:

1. Light pollution almost rules out luminance;
2. 6 panels is quite enough for the time being.

[wimvb]

12 hours ago, Pompey Monkey said:

I want to go deep, and I know there's a lot of dusty stuff in the region too but:

1. Light pollution almost rules out luminance;

RGB is more forgiving regarding light pollution than luminance. RGB filters are usually designed to block the most common light polluters, sodium and nercury. You could try shooting more RGB, and process that with Ha. Or create a synthetic luminance.

Another long term sollution is to install a light pollution filter in the L slot of your filter wheel.

[Pompey Monkey]

39 minutes ago, wimvb said:

Another long term sollution is to install a light pollution filter in the L slot of your filter wheel.

I have considered this. However, the local LP is becoming increasingly broadband... :(

On the bright side (excuse the pun), the county council is moving towards dimming, or even turning off completely, the street lights for environmental reasons!