Sh2-135 in Cepheus - a forgotten nebula

Published by Imran Badr on Sept 28, 2025

This image showcases Sh2-135, a faint emission nebula nestled in the constellation Cepheus, captured over 113h50m hours of integration through narrowband filters and rendered in the SHO (Hubble) palette. In this view, the nebula’s core glows with intricate blue and golden hues, where radiation from massive stars excites clouds of ionized hydrogen, sulfur, and oxygen. Delicate tendrils of gas and dust weave throughout the frame, forming structures shaped by stellar winds and past episodes of star formation. Sh2-135 lies roughly 10,000 light-years from Earth and is part of a rich star-forming region in the Milky Way, though it is rarely imaged compared to its more famous neighbors. The combination of long integration time and SHO mapping reveals the nebula’s hidden complexity, transforming this faint patch of the sky into a vibrant cosmic canvas.

Unexpected Feature in Sh2-135 Imaging

During the acquisition and processing of my 113h50m narrowband SHO dataset of Sh2-135, I noticed a faint, structured emission region located toward the lower left of the nebula. What makes this especially intriguing is that I have not found evidence of this structure in other published astrophotography of the region, nor in a quick search of common astronomical catalogs and databases.

At this point, I cannot confirm whether the feature is a genuine emission nebula or an imaging artifact (such as a halo effect, particularly from the OIII filter). To rule out calibration or processing issues, I will be carefully reviewing my master frames and raw integrations.

If verified, this could represent a rarely documented or overlooked structure in the rich Cepheus complex. Deep integrations like this highlight the potential for amateur astrophotographers to not only create aesthetic images but also contribute to the discovery and documentation of subtle galactic features.

Equipment and Acquisition

Dates: Jul-Sept 2025
Telescope: Sky-Watcher Esprit100ed
Mount: ZWO AM5
Camera: ZWO 2600MM Pro
Filters: Antlia 2.5nm Ha, S2, O3 and Optolong R, G, B
Acquisition:

  • Ha: 22h30m (600s frames)

  • O3: 43h20 (600s frames)

  • S2: 46h30m (600s frames)

  • R,G,B: 1h30m (60s frames)

  • Total Integration: 113h50m