5,000K-7,000K LED street lights vs AP

[Star Dad]

My town (last December) installed blue-white LED street lights. I just got a new ASI294MC camera. The camera worked great out at Cherry Springs State Park in PA (A dark sky gold park). Last week I set up for a night of AP as I usually do and used my new camera. The images are awful. Shooting NGC7000 (North America Nebula) I had to use (in Star Tools) the AMP wipe to remove a brilliantly red background. I cannot now see any part of the Nebula... and I verified I have the correct field using Astrometry.net . Two other set of images I took - if I do a wipe I get horrendous red effects. I'm better off not using wipe at all. I also note that the plethora of stars in these images is seriously lacking. The basically stacked image has a much lighter gray to it than similar photos taken with the Canon 70D. Now, I will admit that the tracking is not good. Something happened to my Polar scope and I'm awaiting the arrival of a Polemaster to fix that, so I did not get a lot of good images - but 30 minutes should show something more than a few individual stars.

So I am wondering if any one else is having a similar experience - and might it be caused by the LED street lights and the ASI294MC sensor? Is the red background I'm seeing caused by the LEDs? If so is there anything I can do to filter out their frequency?

[bobharmony]

I feel your pain. My town just went through the same migration, and my back yard is all lit up. I am able to get good results from StarTools with Wipe and either Develop or Auto-Dev. If I use Auto-Dev, the first pass leaves an amazing orange color with little detail showing. I find that selecting a "Region of Interest" in Auto-Dev will bring out some detail, but still leaves the background a brilliant orange-red color until I pass through Wipe. I just continue on with processing and do another global stretch with Auto-Dev after coming out of the Wipe module. Things don't really normalize until I apply the Color module later in the stream.

In other words, what you are seeing may be "normal" and not a problem. I see these effects with an unmodded DSLR. I don't think the LED streetlight frequency is entirely to blame, but I don't doubt that the additional glow they generate is a contributor to what you are seeing.

Did you make changes to the sub exposure length, gain, and/or offset between Cheery Springs and the backyard? There may be a contribution there if you are getting a lot more background "signal" at home than at the dark site.

If you could show your entire ST process from the log, and your finished image, it might help with troubleshooting.

Bob

[yobbo89]

If the Gradiant reduces as you Travers the sky over the course of the night then you know it's not general sky glow but lp from a direction also even aiming away from a major city will help, it can help to start to image when your target gets higher or away from a source . you should reduce local lp directly comming into your optics, use a tarp screen, a dew shield, turn the bedroom lights of if you're near by ectt.

Unfortunately there's not much else you can do to filter led lp out, the only real solution is to ditch rgb imaging and go narrowband filters or travel to image

[Star Dad]

Thanks guys - will try to re-process NGC7000. It is high in the sky for me right now and because of the polar alignment / guiding issue I only took 120 30 second subs. I'll try your suggestions Bob. And yes, I was able to get reasonably round stars going to 60 seconds for NGC7027. I dunno, maybe I'm over-reacting or overly sensitive to the new camera. It's experiment time, methinks.

Maybe some company will come out with a 5,000K light filter sometime.

[bobharmony]

As an example - this is what my Iris nebula looks like after applying the first pass of AutoDev - it is a result of my heavy light pollution which result in muddy brown subs that are painful to look at as they roll in:

Going through the rest of the process yields this:

Trust StarTools to treat your data well.

Bob

[Star Dad]

Yeah, that is almost exactly what I'm seeing. I'm currently re-processing NGC7027. The first go-around in stacking was absolutely horrid. I somehow ended up with a checkerboard pattern and purple background. I re-stacked the image and now the checkerboard is gone. So maybe there was some bad data in there that I hadn't caught. I had done an automatic alignment in Nebulosity and now I've done a manual one and threw out some "bad" subs.

Once again, thank you - I was terrified that my new camera and the LED lights were a bad mix. But seeing as you have overcome the issue, I just need to work more with StarTools.