IC-1871 - Poll

[Rodd]

I have been working on getting good Ha data for this image with the C11Edge for a while.  Currently I am working with an 8.5 hour stack that has a FWHM of about 2.65.  Not what I wanted, but there are just so many nights I can use up recollecting Ha data.   I thought my only decision was whether to  keep shooting Ha to get the resolution higher, or live with what I have and collect OIII and SII.  However, I am now presented with another option--calling it quits altogether.  I was able to combine previously captured OIII and SII that I collected with a 4" refractor (np101is).  ) I extracted the OIII and SII channels (Blue and Red), and registered the C11Edge data to the refractor data.  I used the C11 Edge Ha as the green channel in the SHO image as well as for a luminance--so the details are all in the Ha channel.  I then up-sampled to return the image to the C11Edge scale.

Poll -1- Do you think much benefit will be realized by collecting OIII and SII data with the C11Edge, given most visible detail is contained in the luminance.  

        2- Regardless of answer #1, do you think it worthwhile to keep collecting Ha until I get some really good data from nights of good seeing ?

 

 

Edited September 26, 2022 by Rodd

[simmo39]

Cant answer your questions, Im no expert but I luv what you have already.

[Rodd]

1 hour ago, simmo39 said:

Cant answer your questions, Im no expert but I luv what you have already.

You are an expert, my friend!

[vlaiv]

1) not much, but possibly some

2) probably not, or rather - that depends how much you want to spend.

You can always improve on your image by collecting more data and then being selective of what subs you want to include in final stack (like lucky imaging approach - discard subs that are not best) - but thing is, with such approach - time will grow "exponentially" (I'm using quotes because I don't think it is actually exponential growth in math sense - rather it will get progressively slower to get better and better results).

Think about it - there are only couple of exceptional nights per year - and if you don't manage to image on those - you'll have to wait for next year (not literally - but you get what I mean) to accumulate some more good subs.

[Rodd]

1 hour ago, vlaiv said:

Think about it - there are only couple of exceptional nights per year - and if you don't manage to image on those - you'll have to wait for next year (not literally - but you get what I mean) to accumulate some more good subs.

Thanks Vlad.  Its exactly right.  Unfortunately (or fortunately from the image's point of view)  I had excellent seeing the first night, so I got a taste of it.  I collected 26 subs that night--but the transparency was poor to start, then opaque (the reason I only got 26 subs).  I was concerned that when combined the stack would be like the subs, pale and dim.  But that was not the case.  This brings up an ancillary question: How bad must a sub be to be too bad to use? 

This sort of begs the question that I have postulated previously--am I wasting my time with the C11Edge.  Recently I compared a Bubble Nebula Ha stack from the TOA 130 and the C11Edge.  The difference was negligible.  I know in those cases the extra aperture equates to speed, but it is sure nice to have 5x the real estate to work with

[vlaiv]

5 minutes ago, Rodd said:

This brings up an ancillary question: How bad must a sub be to be too bad to use?

That is a tough one

In my view - no sub is bad enough to use - if you use it right

They all contain some sort of information - it is only the issue of using that useful information without taking too much garbage with it.

Ultimately - that is something people should not concern themselves about, after all - computer is much better at that sort of thing, so computer should decide how to best utilize such sub. I don't think we are quite there yet in terms of software though.

[Rodd]

5 hours ago, vlaiv said:

That is a tough one

In my view - no sub is bad enough to use - if you use it right

They all contain some sort of information - it is only the issue of using that useful information without taking too much garbage with it.

Ultimately - that is something people should not concern themselves about, after all - computer is much better at that sort of thing, so computer should decide how to best utilize such sub. I don't think we are quite there yet in terms of software though.

That does explain why when I removed subs of low SNR (target was barely visible due to poor transparency) the resulting stack was no better than when I integrated all subs. I guess each sub contributes to the whole, some more than others (well, all exactly the same % but some have higher values so they end up contributing more).  That was surprising. 

[Rodd]

I decided to complete the image using the C11Edge.  Here is a rudimentary HOO bicolor version made with 103 300 sec Ha subs and 41 300 sec OIII subs.  Seeing for the OIII was poor, but I figured there is not much detail in the OIII channel (so much so I abandoned an attempt at collecting more red subs for Stephan's Quintet).  I think after collecting these OIII subs that the final image will definitely be better that the original created with OIII and SII data from a 4" refractor.  I need about 3x more OIII, and an equal amount of SII.  The palette is a bit funky due to the weakness of the OIII channel, but I think the details are a smidgeon sharper and the noise is a tad less (on this screen, anyway--I haven't done my usual round of screens, which is probably a huge mistake).  Balance is better on a whole.  I am looking forward to continuing