NGC 6888

[Rodd]

Bicolor images usually give me a bit of trouble--and the Crescent is no different--not the target, the background.  I suppose it doesn't help that I only used 20 OIII subs.  Quite a bit of noise.  Hopefully the addition of more OIII will smooth out the background and reduce noise in both the background and the target.  The problem is there seems to be significant OIII emissions in some of the background Ha regions--giving them a greenish blue cast that resembles noise due to its thin distribution.  Maybe this is noise and will disappear as data is added.

Conditions for all data acquisition were pretty bad--Ha included.  having almost 10 hours of Ha helped make that channel respectable--though I did bin 2x2 in software due to a general softness (FWHM was 4x the resolution so it was definitely the right move).  But, I did not bin until I finished processing the image-which is not the best way to do it I have been told. I am sure I will fiddle and re-fiddle with this data set until I can add more subs (heaven only knows when that will be).  If I notice a significant improvement by binning right after channel combination as opposed to as the last step I will add it to the post for comparison and as an example to others.

TOA 130 with ASI 1600 Astrodon 3nm Filters

Ha: 110 300 sec

OIII: 20 300 sec  (collected 34 but eliminated 14)

Very little processing done on the Crescent--the background is another story.

 

[Gina]

I think it's good.  You've got more OIII in your image than I had in my last one.

[Rodd]

2 minutes ago, Gina said:

I think it's good.  You've got more OIII in your image than I had in my last one.

Thanks Gina.  I did shoot the OIII with no Moon (a bit unusual for me in that I usually wait to shoot NB when BB is not possible due to the Moon)--maybe that helped a bit

Rodd

[carastro]

Can't seem to view a larger version of the image to check the noise that you complain of.

It seems to have come out quite well to me,   I find even narrowband works better in a dark location, so maybe having no Moon around helps as well.

Carole 

[Rodd]

5 minutes ago, carastro said:

Can't seem to view a larger version of the image to check the noise that you complain of.

That's what binning does--limits the size of the image for full resolution viewing.  You do it when the image cant hold up to full resolution.  I usually don't do this, but sometimes it is nevessary

Rodd

Edit:  On my screen full resolution does make the image bigger--just not as big as an unbinned image.

[Rodd]

Here is an attempt binning early in the processing (directly after channel combination).  That's not the only difference though--I processed it a bit differently.  But the brightness may be due to the early binning--binning helps with SNR.  This is it for me until I get more data.

 

 

 

 

[Rodd]

Well--I could not resist--not sure which is more correct.  Which one is better?

Vlaiv would be proud of me--this one is actually binned 4x4!  Hey if that's what the data can handle.....

 

 

 

[Rodd]

Carole pointed out that the envelope was getting a bit green.  Here is the final image with some of the green removed..  Thanks Carole!

[Gina]

The OIII wavelength is between green and blue.  Anyway, that last image looks great.

[Rodd]

9 minutes ago, Gina said:

The OIII wavelength is between green and blue.  Anyway, that last image looks great.

Thanks Gina--I didn't remove all green.  Not really sure how much is correct.  

Rodd