Sh2-112 from remote

In 2024, I received a high-quality LRGB dataset of Sh2-112 from Insight Observatory. Acquired under the dark skies of Spain, the dataset provided an excellent opportunity to process a relatively little-known emission nebula in the rich star fields of the constellation Cygnus. The deep LRGB data preserve the natural colors of the surrounding stars while revealing the delicate filaments, glowing hydrogen clouds, and intricate dust structures that characterize this fascinating star-forming region.

Sh2-112 (Sharpless 2-112) is a small but bright emission nebula and active star‑forming H II region in the constellation Cygnus, about 5,600 light‑years away in the Orion Arm of our Galaxy.

Sh2-112 is part of the Sharpless catalog of H II regions compiled from Palomar Observatory Sky Survey plates in the 1950s. It is also known under other designations such as LBN 337, DWB 174 and Avedisova 1104 in different nebula and star‑formation catalogs.

The nebula lies in northern Cygnus, roughly 1.3–1.5° west‑northwest of the bright star Deneb (α Cygni). Its equatorial coordinates are around RA 20h 33m–20h 34m, Dec +45° 38′–+45° 43′, placing it in a rich Milky Way field near the Cygnus X star‑forming complex.

Distance estimates cluster around about 5,500–5,700 light‑years (≈1,700–1,740 parsecs). At that distance, its apparent diameter of roughly 15–25 arcminutes corresponds to a physical size of about 25 light‑years across.

Sh2-112 is a roughly circular emission nebula dominated by hydrogen‑alpha light, with a conspicuous dark dust band cutting across its western side in a north–south direction. The field around it is filled with fainter nebulosity and dust associated with the surrounding Milky Way and nearby star‑forming material.

The nebula is ionized primarily by the hot, massive star BD+45 3216 at its center. This is a blue O8 V type star (actually a close double) of about 9.2 apparent magnitude, radiating enough ultraviolet light to keep the surrounding gas glowing.

Sh2-112 sits in a star‑forming region of the Orion Arm, physically close to the complex known as Cygnus X. One study identified around 138 candidate young stellar objects within the nebula, with typical ages of about one million years, indicating ongoing, relatively recent star formation.

The surrounding field is exceptionally rich in stars because the line of sight passes through the dense stellar populations of the Milky Way. Numerous foreground and background stars produce a spectacular backdrop, while careful inspection of deep images reveals faint dark nebulae silhouetted against the diffuse hydrogen emission. Through gaps in the interstellar dust, distant background galaxies can also be detected, adding further depth to the image despite the crowded Galactic field.

The LRGB dataset from Insight Observatory beautifully captures the subtle interplay between glowing ionized gas, obscuring dust, and the colorful stellar population surrounding Sh2-112. The natural color rendition provided by broadband imaging complements the delicate structure of the nebula, highlighting both its scientific significance and its aesthetic appeal. Although often overshadowed by its more famous neighbors in Cygnus, Sh2-112 remains an excellent example of an active Galactic star-forming region and a rewarding target for deep-sky astrophotography.

Data calibration and registration and the final processing was done with PixInsight. The result was as follows:

The images were taken with the following equipment:

• Date: 2024
• Location: Spain
• Telescope/Lense: Planwave CDK20
• Focal length [mm]: 3454
• Focal ratio: 6.8
• Mount: Planwave L 500
• Camera: Moravian C3 61000
• Filter: LRGB
• Exposure time [min]: 190:50:50:75
• Resolution: 0.45″/px (bin 2)