Processing Request/Advice

[MarinerDNA]

My first post here. Been lurking around for a few months now and just getting started with post processing. I'm having a lot of fun despite the early struggles and am excited to learn all that I can from this board.

This is regarding the Horsehead and Heart Nebula.

A couple weeks ago I was testing out a bunch of things for the first time: platesolving, eqmod, Pegasus Powerbox Advance, new cables, spike-a-flat. I installed all the software and drivers and just meant to test all the equipment. It was a full moon but the skies were clear with above average seeing and transparency. That almost never happens in the North West, so I decided to go for the Horsehead Nebula thinking the otherwise good conditions would "make up for some of it," full moon notwithstanding.

I was not expecting PlateSolve2 to do that well on the first try and I had just got my D5300 back from Life Pixel (Ha Mod) so I took a 180 sec test shot and saw the flame Nebula. Screw it. I started the imaging session. 3 hrs of data @180 sec/sub. ISO 200.

The moon was so bright I didn't even need my headlamp at 2am. It was also sitting in the same half of the sky as Orion.

I stacked the subs and opened it in the newer Star Tools beta. My processing is trash right now but I want to know how much the full moon affected the image. There's a huge "gradient blob" under the image and I don't mind that being cropped out. If somebody gets an acceptable image out of this FITS file then I'll know for sure.

Here it is: https://drive.google.com/file/d/1mvBeRs ... sp=sharing

I also did a session with the Heart Nebula the day before; its only an hour+ of data but the full moon wasn't yet over the horizon. When I tried this I had a lot of yellowish gradient that I couldn't get rid of: 26 subs@180sec. ISO 400

Heres that: https://drive.google.com/file/d/13XaeX9 ... sp=sharing

Another question I had was the Spike-a-flat and if those flats screwed me up. I don't have a way to test ADU value so I go by my luminance level being a bit over halfway on the histogram. I noticed a couple dust spots on both images as well.

Here's the master flat: https://drive.google.com/file/d/1pBfG-6 ... sp=sharing


Thank you in advance.

[admin]

My first post here. Been lurking around for a few months now and just getting started with post processing. I'm having a lot of fun despite the early struggles and am excited to learn all that I can from this board.

Welcome!

testing out a bunch of things for the first time

My processing is trash right now but I want to know how much the full moon affected the image.

Don't be too hard on yourself! You're doing a lot of "firsts" at the same time. Some things can have a cascading effect. A divide & conquer strategy is always much better, as you can isolate all variables.

Your flats are indeed not quite helping. Also you will want to start dithering when you got everything else humming along (walking noise is quite visible).
Imaging with the moon out is always going to severely impact the noise in your data as well. Something like Wipe may be able to model and remove the added light, but the noise from the moon light can not be modeled (it is random), so it stays in your signal. So I guess, the TL;DR version of the advice with regards to imaging when the moon is out is; "don't". That's easy for some to say though, as we can't all be out when we want to. Some of use just have to make do with whichever opportunity presents itself.

Anyways, only with the revamped Wipe module's "Uncalib2" preset (which essentially pulls out all the stops), was I able to clean up most of the unevenness;

StarTools_272.jpg (442.59 KiB) Viewed 3462 times

Be mindful that the extreme diagnostics stretch is making the leftover unevenness look a lot worse on purpose, just so you know it is there.
A more reasonable stretch makes things look a lot better already;

StarTools_273.jpg (250.4 KiB) Viewed 3462 times

Default settings for Sharp, Decon, Color (Legacy preset) and Super Structure later, I denoised using the walking noise feature.

You'll end up with something like this;

Horsehead.jpg (186.48 KiB) Viewed 3462 times

The unevenness of the background is still visible (and you can possibly get some more out of tweaking Wipe and using a mask to revoke samples), but really, this should be addressed with flats. You can see the flats appear to correct for dust that isn't there any more as well.

I go by my luminance level being a bit over halfway on the histogram.

That should have done it, however in the master flat, the peak is nowhere near the center of the dynamic range (e.g. it is much darker).

Hope this helps!

[MarinerDNA]

Thank you. I've got a lot to respond with when I'm off work later (graveyard here).

My first reaction is....is that my photo? Lol, that looks so much better than my attempt.

[MarinerDNA]

Interesting about the walking noise, as I'm sure I left on the dither function for Astrophotography Tool. I think once I get my guidescope I'll switch to PHD2's dithering function.

I was wondering if you see the same issues with the Heart Nebula? I forgot to change the ISO of the flat to match the lights (400 vs 200). I chose that target for a couple reasons: to test out the Ha-modification on my camera and...I'm in the doghouse and thought it might cheer up my GF lol.

I'll spend more time on the Heart and re-do the Horsehead Nebula next time the skies are clear. By then I'll buy the latest StarTools and try these myself.

[admin]

It doesn't appear the Heart dataset suffers from walking noise as much, but the gradients/flats issues are the same. Here too the "Uncalibrated 2" was needed to get on top of the very uneven background.