M63 - interrupted by - Aurora Borealis

[decay]

Hi all,

after - as Freddy wrote - 'ages' of cloudy nights there have been a few clear nights here for me. Finally I solved my problem with the guiding of my EQ6-R via KStars / EKOS. I switched off the internal EKOS guider and moved to external guiding via PHD2. This now works flawlessly. I've no idea about the problem with the internal guider. Nevermind

So I managed to get about five hours of light (nights are already pretty short, like Stefan and Freddy wrote) on M63 in two nights:

m63-1-4_01.jpg (371.71 KiB) Viewed 8860 times

M63 is pretty small, even at 1000 mm focal length and "this would be nothing without Ivo's SVDecon" - like Steve wrote. Thanks Ivo!

I would have managed to get a third night, but I wondered that it was not getting dark. It took me some time until I realized, that polar lights illuminated the whole sky - down here in Germany at 51°N! I have never seen the aurora borealis before in my life and I for sure will never forget this night.

DSCN6778_01.jpg (456.36 KiB) Viewed 8860 times

Unfortunately my DSLR was mounted on my scope, so this image was taken with our 10 or 15 year old Nikon P300 compact camera. I'm quite pleased, anyway.

Dietmar.

[Stefan B]

You just have to love that galaxy. Amazing details, Dietmar . And a well tamed core! Did you use HDR?

I have the impression that the galaxy has a slight purple color cast overall. In my experience the core is yellowish and the spiral arms have some blue in them. Maybe the channel alignment is a bit of?

Pity that those pesky auroras prevented you from gathering more data! I still can't get over the fact I missed it The day/night before the auroras we celebrated the bachelor party of my brother , I didn't follow any news the next day and was offline. So I noticed that it was clear that night but went to bed instead of gathering data for my NGC 3718...not knowing what was about to come. The next day I saw all those images and it dawned on me that I might have missed something huge. I will never forgive my brother I missed this once in a lifetime experience

Anyway - great image, Dietmar!

Regards
Stefan

[decay]

Hi Stefan, thanks! Yes, a lot of detail, more than I had hoped for. The sunflower is clearly visible. But honestly, just because of SVDecon.

Thanks for pointing out the purple cast. That seems to be a recurring problem for me. Processed seven (ty-seven) times and still off target. . I think it’s mostly due to a colour cast of my display. One fine day I will have to buy such a fine calibration tool.

But beside of this the rest of the processing wasn’t easy, too. I did an aggressive Wipe to mitigate gradients using the ‘Basic’ preset, but boosted aggressiveness up to 97%. Still not sure when it’s better to use the ‘Uncalibrated’ preset . Then in OptiDev I noticed that the galaxy was quite dim so I pushed Detector Gamma to 1.21 in order to get the galaxy brighter. How did you get your NGC 3718 so bright? I narrowed the ROI and lowered Shadow Linearity to get a dark background. I think I learned that the background has to be quite dark. Only a little bit to much background noise/brightness will lead to this annoying mottling later on in SuperStructure and/or Denoise modules. SVDecon did an awesome job on the structures of the galaxy. Then Colour module with limited Saturation to avoid stars looking like M&Ms, followed by SuperStructure’s ‘Brighten’ and ‘Saturate’ presets in order to bring in some more colour and brightness to the galaxy.
This time I tried a new approach regarding the background: As described above I kept it dark and did noise reduction with a low Grain Size setting of only 2.7 px. The result is some visible noise in the outer faint parts of the galaxy, but the background looks much more pleasing to me. Yeah, I dunno. What do you think? I’m not sure what Steve did with his NGC 3718. Probably he processed a dark background like I did and then dialed in some sky glow using FilmDev?

So you have been offline the day after? I think I know what you’re talking about! Too bad that you missed the aurora borealis. But it was a bit of good luck for me, too. In the forecast they told us it would be visible at about 4:00 am, but actually it was much earlier. To be honest, I haven’t thought it would be visible at all. So I set up my rig and we settled down on the couch to watch some TV. Now and then I had a glimpse onto my remote EKOS session and at about midnight I wondered that my lights have been _much_ brighter (and very red!) than the night before. Otherwise I would probably have gone to bed too.

Best regards, Dietmar.

[fmeireso]

Nice shot, Dietmar!

Quite some detail. Personally i find the purple cast not that overwhelming but apperently this galaxy tends to look a bit purplish on pictures. I commented on a dutch forum about a picture that had definately a purple cast, but otherwise also great detail.

But indeed, polar light spoiled the evening. I had it too. I was taking test images with my new RC 8' and after a while i noticed the background started to be yellow orange and eventually turning to red. I had no clue what was going on, suspected dew, but what the heck why should it turn red. The following morning my wife mentioned there had been much polar sightings in Belgium and then only i putted one and one together...

I had several subs i could not use, very brick red background and fading stars, like overexposed and that by northern light , would you believe it...

Glad to see at least you could make an image, my catch was rather poor that night.

CS
Freddy

[decay]

Hi Freddy! I agree, this galaxy looks often a bit purplish on images. I think this is because it shows lots of HII regions in it, probably often pronounced by NB accents. These red accents together with the blue of the spiral arms may give a purple impression. And those rich dust lanes may lead to some kind of colour cast, too. I’m currently working on a new version using stronger deconvolution and additionally HDR which will improve detail a bit more. And I will dial in _some_ green, but not too much.

I commented on a dutch forum about a picture that had definately a purple cast

I found the blog post you mentioned on astroforum.nl and indeed this image looks purplish. The outer arms which should be blue obviously show a colour cast. The core is blown out a bit, this guy should have used ST and it’s HDR module! But I like the overall appearance including the background and the balance of noise reduction.

But indeed, polar light spoiled the evening.

I had to discard the whole night. All frames have been much too bright. But it was worth it. The forecast told that the polar lights would probably only be red but actually even green was visible for the eye with some dark adaption.

Glad to see at least you could make an image

Yeah. Of course, astro photographers always complain about the weather, that’s part of the game and of the human nature, I guess. And which is totally fine. And this region a Germany is known to have lots of rainfall and clouds, but the last 9 month really have been a pity ...

I was taking test images with my new RC 8'

I’m looking forward to see the first images you will gather with your RC 8’ Maybe these small galaxies will get better into reach having it’s increased focal length.

Best regards, Dietmar.

[Stefan B]

Hi Dietmar,

sorry for my late answer!

Thanks for pointing out the purple cast.

It's not particularly strong and as you said, many M 63 images look similar. But it's been my impression there could be a bit more differentiation of colors.

How did you get your NGC 3718 so bright?

Well, part of the answer is the 'Brighten' preset in SS. But after finishing I still had the impression that the galaxy is too dim so I went to 'Curves' in PS Adjusting the brightness of the galaxy without affecting stars etc. too much was a matter of seconds. Don't know what I have done to signal fidelity...

In terms of noise reduction, background brightness etc. I consider your image well balanced and a fine picture. In my eyes the default denoise is sometimes a bit too strong and I tend to throttle it down or to equalize noise grain which results in a result similar to yours.

Regards
Stefan

[Mike in Rancho]

Great Aurora image, Dietmar! Neat you can see the high magentas and low greens.

That was a fun night. Of course, just as with the eclipses, I was ill-prepared.

Instead of just leaving my camera and tripod out there, and in a predetermined "good spot," each time I saw the data coming in for increased activity (there was about a 30 minute lead time, depending on solar wind velocity), I would go back out and plop everything down in a new place to try again.

In retrospect, had everything been in one spot I could have put together a time lapse, after enhancing each frame. Oh well...next time.

To the naked eye, way down here, the north just didn't "look right," but if I didn't already know about the big Aurora I wouldn't have noticed. Probably would have just figured the light pollution was a bit pinkish, for whatever reason.

No low-down greens, unfortunately, at least at the time I was out there. The ridge of the San Gabriels and peaks up to about 9K feet block me off up to around 12° alt though, of course. The only way I was able to really get anything captured was actually with the full spectrum D5300 (UV-IR cut filter on the lens). I raised the green channel a bit to try to white balance things out, and get my trim seemingly white. As it was only a 2 second exposure I brightened things up (gamma correction!) and saturated.

Too bad I couldn't run some HDR or ST stuff on it. Almost like red nebula! You can kind of maybe just barely make out a vertical pillar right over the top of the big mountain. In a prior frame it's not there. I still might try to see if I can time-lapse what few frames I have to show the shifting.

DSC_0962 5-10-24.jpg (467.75 KiB) Viewed 8175 times

[decay]

Polar lights visible way down in Southern California! Who would have thought?!

I was ill-prepared.

I was ill-prepared, too. Mostly, because I just didn’t believe that there would be anything to see or to photograph. And than I only had my compact camera mounted onto a super tiny tripod, crawling in the dirt to find reasonable places for shooting . Time-lapse would have been cool. Yeah, maybe next time.

Nice picture, anyway. Featuring great San Gabriels barely visible through some pale haze under a purple sky. Looks kind of surreal.

My image is not post-processed. Probably to noisy … don’t know. Perhaps I will try, anyway. There are a few more nice images I took, but they are prominently featuring the house of our neighbor, so I can’t post them online.

Dietmar.