vdb 152

[Stefan B]

Hi everyone,

since dark dusty nebulae are just awesome I tried one again although they are pretty hard to process. You have to push the signal a lot and all the little faults of your data become visible...

I pointed the scope at vdb 152 in Cepheus. vdb 152 is the bright reflection nebula to the right of the dust but not the dust itself. It is one of my deeper exposures and during processing of the broadband stuff I noticed some faint emissions from Ha and probably OIII. So I gave that another night with a duo NB which resulted in a nice addition of color in the lower half of the image.

Does anyone know what that nebula with the Ha/OIII signal is? PN? Or is there an easy way to find out? Astrobin's basic plate solve doesn't find anything except for some stars...

See https://www.astrobin.com/zgf136/ for details.

Regards
Stefan

[decay]

Hi Stefan,

you are doing really crazy things But I agree, these are very interesting objects and the result you got is quite impressive.

Maybe I found some information about the nebula you asked for:

https://www.spaceimages.de/astrofotos/nebel/vdb-152

(I'm sorry, it's in German. But today it's easy to use Google translate or something similar.)

If I understand correctly, it must be LBN 538.

Best regards, Dietmar.

[Stefan B]

Hi Dietmar,

Thanks for your kind words and your research!

(I'm sorry, it's in German. But today it's easy to use Google translate or something similar.)

For me, German is fine

If I understand correctly, it must be LBN 538.

Thanks, obviously you're right! LBN...Lynds' BRIGHT nebula...Lynd must have been a real joker. Almost five hours with a duo NB filter and a 571 sensor and almost nothing of that bright nebula is showing up. To show it like in my image I had to stretch like hell and blur heavily. And bring it into the image with selective masking...actually nothing I like to do, but otherwise the five hours would have been wasted. LBN...bright my ***

Anyway, I found that it has been thought that LBN 538 was a PN but it is now considered to be part of the interstellar medium ionised by a white dwarf (https://www.imagingdeepspace.com/deht5.html).

Thanks again, Dietmar!

Regards
Stefan

[Mike in Rancho]

Interesting, Stefan!

Nice crisp and colorful stars. Stars and Spikes Forever. That should be a song.

Dust is hard. I like the color of the dark nebula, that's my favorite when it shows a bit of orange-brown tint. The red and blue looks a bit too strong maybe?

[Stefan B]

Hi Mike!

yes, I agree, dust is hard

The red and blue looks a bit too strong maybe?

Can you be more specific? Too strong in terms of color balance or saturation? In the stars, the reflection or the emission stuff? Or all of it?

Color balance seems okay, judging from the histogram. Maybe the balance is already too much shifted towards the blue since there are barely red stars visible but rather orange/yellow ones. But with the balance shifted a bit more red the dust looked strange.

Saturation is of course always a matter of taste and my images are rather saturated. That's fine

But maybe the blending of the emission nebulae could have been more subtle. I wanted the duo NB night to not be wasted. Maybe I wanted it too much?

Regards
Stefan

[Mike in Rancho]

No Stefan I thought the stars were great.

It's more the red and the purple of that...blob. It just seemed out of place, perhaps? Stellarium shows little of this object, and perhaps even less when the digital survey is turned on. But I searched for images and no small number of them are in fact pretty saturated to show this region.

Quite interesting! This seems to be a pretty tight field of view you have? It's kind of hard for me to size up, even when I have my FOV rectangle turned on in Stellarium.

That said, some of the images I found were wider FOV of the area, and looked quite amazing. I think that helps put the red curves and blobs in context, with the dark nebula portion. I'll have to try to size this up, though I imagine it is pretty faint and would take a lot of time?

[Stefan B]

Hi Mike,

okay, got it, the emission nebula. Yes, you're right. I've already spent multiple iterations on processing the data, NBAccent among them, before getting the result I posted. NBAccent didn't really work since broadband, Ha and OIII needed different Wipes, so I splitted the data from duo NB in Ha and OIII and gave them seperate processing flows. Afterwards I combined broadband with Ha and this merge was then combined with OIII. I messed up during coloring the 'mono' images which resulted in an odd appearance. Nonetheless, it looked better to me than without it. And I had no more energy for new iterations of processing/coloring/combining so I called it a day...

My complete FOV is usually 1.7° x 1.1° by the way. But here I had to crop since I had multiple nights and there's always a certain amount of offset, also in orientation when I don't get the camera rotation spot on. But the biggest offset arises when combining broadband and duo NB stacked in ASTAP. To my knowledge you can't choose a reference frame in ASTAP. Instead it uses the frame which appears best from statistics (HFR, star count...). Due to dithering etc. the chosen frames for broadband and duo NB might not share the biggest overlap, right? And thus you have to crop quite a bit...

Regards
Stefan

[Stefan B]

By the way, this is how it can look like with a mono camera and shooting from a dark site (today's image of the day from Astrobin):

https://www.astrobin.com/ud1835/

[Mike in Rancho]

Not surprised on the IOTD. What a beautiful region.

I will have to try this. Just LRGB? I do have Ha, but not OIII filter just yet.

My FOV seems a tad bigger, looks like I am 2° 20' x 1° 33'.

I am still learning NINA myself, but are you using the framing wizard and saving the sequences? That seems to be able to get me back to where I want, though sometimes I have to jump through a few hoops pressing buttons and changing screens.

What I do now for a subsequent night on target, is after TPPA I will just go into the imaging and take short test shots that I then hit the plate solve button for, which gives the rotation. Then I rotate the camera (I already have degree marks on a piece of tape around the visual back), and repeat as needed until I am very very close to the rotation of the prior night. I'm kind of OCD so I will get the degree to within tenths if not hundredths.

[Stefan B]

I will have to try this. Just LRGB? I do have Ha, but not OIII filter just yet.

OIII will only help with the blue part of the emission nebula (which is outside the FOV of Astrobin's IOTD). Otherwise it's only broadband and a bit of Ha.

I am still learning NINA myself, but are you using the framing wizard and saving the sequences?

Yes, doing exactly that. I usually get back to the spot very well although there's a certain tolerance (100 pixels or so). Rotation plate solve seems a bit imprecise. For example, if I dial in the rotation to 80.7° (target: 80°) in the FOV where I focus and calibrate my guiding and then slew to my target the rotation is often different, e.g. 81.3° although it shouldn't have changed. Or I had 80.1° during the first part of imaging and after the meridian flip and without touching the camera plate solve tells me the rotation is 80.6° or so. So my impression is that the calculation of the rotation angle has a certain degree of imprecision resulting in a bit of offset. But I can live with that.

I also have the manual rotator turned on that tells me to rotate the camera if it is off more than +/- 1 degree.