NGC7538 – often imaged, rarely focused on

About the Object

NGC7538 is an emission nebula in Cepheus. It is located in the outskirts of the extended emission complex near the famous Bubble Nebula and the Lobster Claw Nebula (the claws basically pointing towards NGC7538), and can thus be found on many images of the Bubble environ - but much less frequently it is in the focus of an image. So the right target for long focal length maniacs ...

Observation Notes

I put it quite bit off center so it nicely balances with the dark region at about 2 o'clock of NGC7538. I processed the image as an HOO (with a lot of non-linear processing of H and O separately owing to the large difference in brightness and extension in these two lines) and than gilded on the Sii signal in green resulting in yellowish colors in strong Sii regions.

Data were taken on 2025 September 6,7,8 and 11

Technical Details

View the full-resolution image together with complete acquisition and processing details on AstroBin.