SharpCap Forums

NGC 7129 in NIRGB, NIR and RGB

Ever since I started using this telescope and form of photography in 2020, NGC 7129 has been on my list.
But every time I was put off by the fact that so little of it is visible (except the core), especially here from the city with Bortle 6/7.
But this year: no more excuses! I also had read about the strong Near IR (NIR) in this object, so I shot data from that too.

In the end, just under 19 hours of data (12:07 hours of RGB and 7:50 hours of NIR) and hours of editing (read: experimenting )
After testing, I decided to stack the RGB data in SiriL (using SiriLic) and save it as Ha (G) and OIII (B).
The NIR data normally stacked and used as R data.
In Photoshop I placed these in the respective RGB channels
This method turned out to be the easiest and gave the best results compared to separate stacks of RGB and NIR and then splitting, mixing, etc., etc. the channels in Photoshop.

The links to the original shots (2400 x 2700 px) are in the text here.

NIRGB: https://i.ibb.co/WkcLQc9/NGC-7129-NIRGB.jpg
There are two things that immediately stand out: the bright green parts that contain no NIR data at all. These are the HH (Herbig Haro) objects.
And just below the center the clear tuft. This is RNO 138, a bipolar reflection nebula which is stronger in NIR than in RGB.
Everything that is green(ish) is therefore (very) weak in NIR. Everything that is red(ish) is (very) strong in NIR.
And it just gives a very nice overall picture in a combination that I have never seen before

NIR: https://i.ibb.co/4FBXnYW/NGC-7129-NIR.jpg
A surprising amount of NIR data visible. The core is a lot less "outshined", making the stars more visible. Disadvantage: with the IR Pass filter, halos appear on the bright stars. Partly that is why the crop.

RGB: https://i.ibb.co/ZS74jCc/NGC-7129-RGB.jpg
I honestly expected more from this. But I think I got the most out of it and that only a darker spot would help.
And a larger scope

Menno


NGC 7129 NIRGB
NGC 7129 NIR
NGC 7129 RGB
Bortle 6/7
Meade LX200 8" f/10 ACF OTA
Ioptron CEM25EC mount (no guiding)
Optolong L-Pro filter
Astronomik ProPlanet 742 IR-pass filter
Zwo ASI071MC Pro camera

Captured with SharpCap Pro @ -10 Celsius / White balance R50 B50
L-Pro: 44 x 180 sec / Gain 90 / Offset 4 + 107 x 300sec / Gain 90 / Offset 4
IR-Pass: 94 x 300sec / Gain 90 / Offset 4
Darks + (dark)flats

Stacked with SiriL (m.b.v. SiriLic)

Processed in SiriL and Photoshop

Hi Menno,

nice image - I always admire those who put tens of hours into a target!

You have also hit a signficant milestone in the post count (1024 - us programmer types like powers of 2). Thanks for your contributions to the forum

cheers,

Robin

Thanks Robin
Sometimes long(er) integration time is both fun and necessary. I'm not really a fan of it since my set-up is not automated and I have to keep an eye on the tracking all the time. But on the other hand that's my way of doing it, which I like , so in the end it's a win/win.

And your so welcome.
1024 has not really a meaning for me ... other than that if you mix the digits, you get 2014 and that was an important year for me

Menno

Very nice Menno! Interesting to see the data in NIR as well . Tim

Thanks Tim
The NIR data indeed is interesting. For me really the most interesting part is the almost total absence of the HH objects.

Menno

Hi Menno. A very late additional comment. Just thinking about the significance of the lack of (~ 800-900 nm ?) NIR from these HH objects and reflecting that it probably particularly makes sense for an HH object ? Well at least if I understand the attached publication correctly - which I may not of course. The 'shock'- stimulated IR line for molecular hydrogen appears to be at a wavelength ~ 2200 nm - so probably not 'near' enough? Tim

https://www.aanda.org/articles/aa/full_ ... 61-09.html

Hi Tim

As I understand it, these MHO objects mentioned in that article are only (or mostly) showing in NIR. They knew about HH objects in visual and Ha but they discovered HH objects in NIR that were surrounded by dust. That is at least what I understand from https://en.wikipedia.org/wiki/Herbig%E2 ... unterparts
So it's the opposite of what I captured where the HH are not showing in NIR.
Posted a question about it just now on CN, maybe they have an answer there

Menno