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Attached are examples of the effect of the numerous satellites that leave light trails on long exposure astronomical images.
Micheal Jaeger posted this exceptional image of C/2025A6 Lemmon taken on 20251026. It is a mosaic image showing the total extent and structure of the ion tail.
The first image shows the image marred by the satellite light trails and the second image is the result of 6 hours work on the image to digitally remove the satellite trails.
I know there are some who argue that the ability to digitally remove these trials means that the problem is diminished, but as the number of satellites increases the work to digitally remove them is going to become increasingly difficult, if not impossible.
What a shame that for all the good that technology can bring it comes with a huge downside for astronomers and epsecially imagers.
Micheal has given us permission to publish his images within the BAA.
Here are his comments:
After six hours of work removing the satellite tracks, we can now show the finished result from Sunday evening.
The tail shown here is longer than 15 degrees.
C/2025 A6 Lemmon 2025-10-26 18.00 UT mosaic 15/15min filter blue Leica-Apo-Telyt f-180/4.0 QHY600,
Michael Jäger, Gerald RhemannMichael’s images are fantastic but I wonder why he doesn’t take more, shorter exposures although I’m not clear what his sub exposures are. It says 15×15 minutes in your description but that is almost four hours so that can’t be right. CMOS sensors have very low read noise and can be read out very fast so doing short exposures is not normally a problem and it allows you to stack statistically to remove sub frame pixels affected by satellite and aircraft trails. My image from here last night:
https://britastro.org/observations/observation.php?id=20251027_224004_df7ddf0b98656b8c
had multiple satellite trails per frame but none are visible on the final stack of 21x30s frames.
Jeager and Rhemann are undoubtedly the best comet images in the world so I must be missing something about their technique. It is unfortunately the case that comet imagers are badly affected by the mega-constellatons since we are imaging with wide-field, fast optics in twilight but there are solutions which don’t involve manually removing trails from each image.
This was discussed in my talk at the recent comet section meeting around 26 minutes in here:
https://britastro.org/video/2025-10-04_Comet_Section/03%20-%20Edinburgh_NDJ.mp4
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