wimvb

That says a lot about the quality of those videos. I normally use arcsinh stretch for rgb and histogram stretch for L. I apply the latter in small increments.

The stf is much too aggressive for a permanent stretch. It’s function is to show as much detail in a linear image as possible. It does this by bringing in the black point and white point and moving the mid point to achieve maximum contrast. If stf is applied permanently, you suddenly need to fix things that didn't need fixing before.

This seemingly casual remark is at the heart of the matter. What is "more or less" in this case? The purpose of all the bells and whistles in WBPP is to make as much use of all the data to create one final stacked image of the highest quality possible. "High quality" for me means low noise, efficient small and large scale pixel rejection, removing uneven areas in subexposures due to the occasional cloud passing (local normalisation), etc. Furthermore, when you understand what WBPP does, you'll find it much more transparent than DSS. It gives more control over the stacking process, but the price you pay for this is a more complex process. For example, what is the "score" in DSS based on? Why reject a fixed percentage of frames, rather than using a quality threshold? (Maybe this has changed in DSS. I haven't used it for a long time, but when I used it, this lack of transparency annoyed me.) In PixInsight I use image weights based on a metric of my choice (noise, fwhm, eccentricity, etc), combined with a minimum weight to control the image integration process. If half of my subs are bad because focus drifted or poor guiding resulted in increased eccentricity after a meridian flip, image weight will tell me that. DSS with a fixed percentage would possibly try to stack poor subs and give an inferior result.

That's your main culprit. TGV denoise mainly removes small scale noise but can leave blotches, which is probably what we see here. As others have written, use noise reduction when you need it, after stretching. The best noise reduction, and the only way to reveal weak detail, is to have more data. To get rid of larger scale colour noise, use MMT applied to chrominance with 7 or 8 layers activated, and a mask that protects the main target and partly even the background. (This is the same as mixing the treated image with the untreated image). Also, use curves stretch to control the stretch applied to the faint areas. SCNR is the best way to remove a green cast. But I seldom use it at full strength, because it can leave a purple cast where the sky is supposed to be neutral. Try it at 0.4 - 0.6 strength.

Very nice! So, how do you apply the zone system in astrophotography? 😉 stars in zone 10, and everything else in zone 1. Joking aside, I understand what you’re aspiring to. He was the true master of HDR b/w photography.

Not the galaxy of this thread, but I used TypeCat in PixInsight to make a list of the globular clusters of M81. I then used that in the Image annotation script.

Looks very good to me. PM me if you want some more data to process. I think we've had more luck with the weather than you.

Definitely try it on a galaxy and see how it affects colour balancing and colour calibration in post processing.

Thank you, Göran, for your kind words.

The H-alpha signal after 30 minutes (7 exposures before the clouds put a stop to it). Faint doesn't even start to describe it, but with another 10 hours or so, I should be able to combine it with the RGB data. This is just integrated, inverted and stretched. Image calibration with darks only.

Thanks guys. Very much appreciated

Unlike its closer cousin, you can count the images of this galaxy on one hand, even if you include professional images. In all fairness, it is very easy to overlook this galaxy, since it isn't much brighter than the molecular clouds that surround it. It is about 30 Mly distant. Ugc 12632 (PGC 71596) is a spiral galaxy in the constellation of Andromeda. It is part of a group of galaxies, together with ngc 7640 and ug 12588 ( https://www.astrobin.com/a8ot9h/ ) Technical details: 19 hours 48 minutes integration time, of which about 8 hours L and 12 hours RGB. Telescope: SW 190MN Camera ASI294MM with Optolong RGB filters Processed in PixInsight

Either Vizier from the university in Strasbourg, or a script called TypeCat in Pixinsight You can access Vizier from the Simbad database/front end or from aladin. All from Strasbourg https://simbad.cds.unistra.fr/simbad/sim-id?Ident=M 87 TypeCat uses Vizier and creates catalogues that can be used directly in PixInsight's image annotation script https://www.skypixels.at/HVB_Repository/

That was an image that I only processed. The data came from the IKI observatory:

Too far south for me, I’m afraid. I may try to capture some further North. Any suggestions?

GC hunt? Here's what I managed some time ago https://stargazerslounge.com/topic/404408-ngc-185-a-dwarf-galaxy-and-its-globular-clusters/ https://stargazerslounge.com/topic/402885-ngc-147-with-globular-clusters/

That’s a very nice M31

It's 4pi steradians as seen from anywhere. 🙃

Excellent! RASA does it again. You must have so many RASA widefield images by now that combined they should cover most of Cygnus and its neighbours.

That’s an impressive Loch Ness Olly.

I did the same. Combined the R, G and B masters in image integration without pixel rejection. I may have darker skies, since I could see the faint parts of the galaxy in the superstretched synthetic L after 7.5 hours of imaging time.

Very nice already. Adding L will bring out the faint arms/shells of ngc 7550.

Thanks, Chris. It is one of kind. If it were any closer it would probably be a very popular target.

I've only used 0 gain for all my imaging, and flat fielding hasn't really been a problem for me. What I see here is first and foremost a subtle banding and noise at high signal, both of which shouldn't be there. What my tests also show is that this anomaly disappears for gain 139 and higher.

yes. It will be interesting to see your result. Good luck.