Observation issue. Advice needed.

[Jnicholes]

Hi everyone,

I have an issue, and I need advice. I am positive other astronomers have this issue, by the way.

Have you ever had a satellite photobomb a good exposure? This has happened to me a few times. Here is one example:

C/2022 E3 (ZTF) See the line? Satellite.

I went online to Stellariumweb today, to find out ZTFs coordinates. I discovered this:

See all the satellites? All say the same thing: STARLINK.

This is a legitimate issue. Obviously, theres nothing we can do about satellites, but they keep photobombing exposures. Here is my question, how do you all deal with this issue? Do you just do an exposure and hope there is no photobomb?

Jared

[OzEclipse]

Hi Jared
Take multiple exposures, stack on 'median' or similar averaging algorithm in your favourite stacking program. There's only one satellite track and 10,20, 50, 100 other sub exposures. The tracks disappear through the statistical averaging.

I had this happen just last night. The first image is one 30 second sub complete with airplane trail.
The second is that image, averaged as one of just six stacked images. You can see the trail is gone.

The first image is a jpg written direct from the raw sub. The second image is a straight stack of six, stacked on median, no other processing or tricks applied.

cheers

Joe

[Jnicholes]

Thanks for getting back. I appreciate it. I have two follow up questions.

First off, what DSO is that?

Second, I take my photographs with my phone, specifically an app called NightCap. I attach the phone to the eyepiece. It lets me do long exposures. With this process that you recommended me, would it work with exposures taken on my iPhone 11 with this app?

[jrkirkham]

I second the idea of taking more than one exposure then dropping out the bad ones before stacking. I'm not sure, but I would think a stacking program would work on iPhone shots. I don't have an iPhone. If you only have one frame you could probably open that frame with an photo editing program and clone out the satellite trail.

[OzEclipse]

Thanks for getting back. I appreciate it. I have two follow up questions.

First off, what DSO is that?

It's NGC 3372, Eta Carina


Second, I take my photographs with my phone, specifically an app called NightCap. I attach the phone to the eyepiece. It lets me do long exposures. With this process that you recommended me, would it work with exposures taken on my iPhone 11 with this app?

I am not familiar with the program. Providing you can export each image as a standard file format [TIFF, JPG, ETC], then any stacking program should be able to deal with those files.


Rob is a very experienced photographer. I agree with him that the best way is to delete bad subs before stacking. However, the advice I gave you was not to worry about deleting the images with satellite trails. You can just stack them. In the example I gave you, one of the six subs that I stacked to make the second image, was the first image with the aircraft light trail.I was assuming that you are using basic equipment, have limited time, and each sub is precious.

You can use those trailed subs in your stacking providing you have 5 or more images to stack, the trails will vanish.

Joe

[Jnicholes]

Thanks for getting back. I appreciate it. I have two follow up questions.

First off, what DSO is that?

It's NGC 3372, Eta Carina


Second, I take my photographs with my phone, specifically an app called NightCap. I attach the phone to the eyepiece. It lets me do long exposures. With this process that you recommended me, would it work with exposures taken on my iPhone 11 with this app?

I am not familiar with the program. Providing you can export each image as a standard file format [TIFF, JPG, ETC], then any stacking program should be able to deal with those files.


Rob is a very experienced photographer. I agree with him that the best way is to delete bad subs before stacking. However, the advice I gave you was not to worry about deleting the images with satellite trails. You can just stack them. In the example I gave you, one of the six subs that I stacked to make the second image, was the first image with the aircraft light trail.I was assuming that you are using basic equipment, have limited time, and each sub is precious.

You can use those trailed subs in your stacking providing you have 5 or more images to stack, the trails will vanish.

Joe

Thanks for getting back. Your advice will work for me. When I transfer the photos to my laptop, they turn into jpegs. I can do an experiment, I’ve got plenty of photos of that comet on that same night. I’ll see if it yields good results.

[KathyNS]

I don't recommend dropping frames with trails from a stack. With all the satellite "constellations" being launched these days, pretty soon every frame will have a trail. If you are going to stack multiple frames, any stacking software will have options for eliminating trails. Even a simple average will reduce them.

Clipping algorithms in the stacking software can completely eliminate them. If you have six frames and one has a trail, the stacking software will use all six frames for the majority of pixels, but will only use the five frames without a trail for the pixels that have the trail in the bad frame. This works well for all but the very worst of low-flying-aircraft-with-their-landing-lights-on trails.

[Jnicholes]

Thanks for getting back. I appreciate it. I have two follow up questions.

First off, what DSO is that?

It's NGC 3372, Eta Carina


Second, I take my photographs with my phone, specifically an app called NightCap. I attach the phone to the eyepiece. It lets me do long exposures. With this process that you recommended me, would it work with exposures taken on my iPhone 11 with this app?

I am not familiar with the program. Providing you can export each image as a standard file format [TIFF, JPG, ETC], then any stacking program should be able to deal with those files.


Rob is a very experienced photographer. I agree with him that the best way is to delete bad subs before stacking. However, the advice I gave you was not to worry about deleting the images with satellite trails. You can just stack them. In the example I gave you, one of the six subs that I stacked to make the second image, was the first image with the aircraft light trail.I was assuming that you are using basic equipment, have limited time, and each sub is precious.

You can use those trailed subs in your stacking providing you have 5 or more images to stack, the trails will vanish.

Joe

Here are the results using a simple Registax program.

As you can see, I accidentally formed some double stars. Probably just an alignment issue. However, at least I got rid of the trail!

[Jnicholes]

I forgot to set something in the previous stack. Here is the correct one.

Thanks a bunch!

Jared

[JayTee]

This is exactly the content that should be in this forum.

Thank you for contributing.

[Jnicholes]

This is exactly the content that should be in this forum.

Thank you for contributing.

No problem. It is a serious issue in my opinion. Lots of satellites are getting launched into space. They are constantly ruining observations not just by me, but others. In a way, the satellites are ruining the night sky.

At least we’re working to find a solution towards getting the satellites out of exposures.

[OzEclipse]

This is exactly the content that should be in this forum.

Thank you for contributing.

No problem. It is a serious issue in my opinion. Lots of satellites are getting launched into space. They are constantly ruining observations not just by me, but others. In a way, the satellites are ruining the night sky.

At least we’re working to find a solution towards getting the satellites out of exposures.

When I was starting out in astronomy in the late 1970's, spotting a satellite crossing the relatively small field of view of my eyepiece during visual observing, was extremely rare, a couple of times in my first five years.

Currently, I spot satellites photon bombing a 0.5 deg field of my 18" multiple times every single night out. Each time this is usually followed by a load exclamation of, expletives aimed at Elon.