Telescope Sky-Watcher 250PDS 254/1250mm

Camera Touptek 2600C

Filters Scorpio 3nm Dualband Ha+O3, Askar D2, Antlia RGB Triband

Mount Sky-Watcher EQ6-R Pro

Exposure 6+4+7.5 Hours

Date Aug, Sep 2025

Acquisition Details

Capturing the Pacman Nebula from my backyard was my early autumn project. Given its angular size, I used my large SW 250PDS Newtonian telescope to capture the details of the Pacman Nebula. I used all three available filters in turn—that is, both the Ha+O3 and S2+O3 Dualband filters, and finally the RGB Triband filter to capture the star field and the background area of the nebula. Unfortunately, the weather only allowed me to collect a limited amount of data, so I would like to return to this interesting object at the earliest opportunity.

NGC 281

The Pacman Nebula (NGC 281) is a bright and busy H II region located in the constellation Cassiopeia. Named for its uncanny resemblance to the classic arcade game character, this cosmic cloud is munching its way through the Perseus Spiral Arm of our Milky Way. Located roughly 9,500 light-years away, the nebula is powered by a central open star cluster and features towering dust pillars and dense Bok globules where new stars are rapidly forming.

Key Astrophysical Data

Catalog Designations

NGC 281, IC 11, Sh2-184, Pacman Nebula

Position in the Sky

Cassiopeia (RA 00h 52.9m / Dec +56° 37′)

Sky Location Map

✨ Open in Stellarium Web

Apparent Size

35′ × 30′ (Slightly larger than the Full Moon)

Apparent Magnitude

7.4 mag (Visible in small telescopes under dark skies)

Discovery Date

August 1881 AD (by E. E. Barnard)

Object Type

Emission Nebula / H II Region with Open Cluster

Distance from Earth

~9,500 Light Years

Physical Size

~96 Light Years across

Power Source

HD 5005 (Massive multiple star system within IC 1590)

Object Overview & Facts

Visual Appearance & Pareidolia: NGC 281 earned its popular nickname, the "Pacman Nebula," due to a prominent dark dust lane that cuts sharply into the glowing emission cloud. This wide, wedge-shaped silhouette creates the distinct appearance of a gaping mouth, making the nebula look like the iconic 1980s video game character eagerly devouring the cosmos. The bright core serves as the eye, completing the illusion perfectly in optical imagery.

The Central Engine (IC 1590): The energy driving the Pacman's intense glow comes from the young open star cluster IC 1590, located right in the center of the nebula. The primary powerhouse within this cluster is the multiple star system HD 5005, which contains a blisteringly hot, massive O-type star. The fierce ultraviolet radiation and stellar winds from this system are ionizing the surrounding hydrogen gas and blowing an enormous bubble outward, actively carving out the nebula's interior structure.

Bok Globules and Star Formation: Scattered across the face of NGC 281 are several prominent Bok globules—dense, dark, and extremely cold knots of dust and molecular gas. These teardrop-shaped dark spots resist the harsh radiation of the central stars much better than the lighter surrounding gas. Deep inside these thick cosmic cocoons, gravity is working to collapse the material, forming protostars. In the future, these newborn stars will eventually emerge and further disperse their birth cloud.

History of Discovery: The Pacman Nebula was discovered by the renowned American astronomer Edward Emerson Barnard in August 1881. Barnard, known for his keen eyesight and pioneering work in astrophotography, spotted the nebula while observing the northern skies. It was later added to the New General Catalogue as NGC 281. The central star cluster, IC 1590, was cataloged separately due to its distinct grouping of young stars.

Astrophotography Guide: For amateur astrophotographers, NGC 281 is an excellent autumn target that rides high in the northern hemisphere. Its apparent size makes it a great fit for medium focal length telescopes. The nebula emits very strongly in Hydrogen-alpha (Hα), which provides the rich structural detail. However, processing it in the Hubble Palette (SHO) reveals stunning color separation, where the sulfur traces the outer edges, hydrogen forms the golden core, and a delicate blue envelope of Oxygen-III adds three-dimensional depth to the 'mouth' region.

Deep Sky Objects Size Comparison Laboratory

Interactive Scaling Explanation: This panel acts as a dynamic comparator of angular sizes in the night sky. All selected objects are rendered exactly over each other from a common center, allowing an immediate, direct comparison. The Full Moon (diameter 31') serves as a permanent baseline reference.

Cosmic Time Machine: NGC 281 vs. Earth's History

Present Day Photon Departs (9,500 ly)

Year 2026 AD

The Photon Arrives: Right now, the light captured in this photograph is ending its 9,500-year journey through deep space, hitting your camera's digital sensor. Move the slider back in time to see what humanity was doing while these precise photons were rushing through the void.

Cosmic Scale: Distance Map Laboratory

Dynamic Linear Scaling & Manipulation: This view builds an interactive, deep-space linear cosmic coordinate system. When swapping objects, the line auto-calculates its limit. Leave only near targets (Pleiades, Orion) checked to reveal detailed stellar gaps inside our galactic neighborhood. Turn on remote galaxies (Andromeda, Whirlpool) to watch the Milky Way bundle together on the left margin. Use your mouse wheel to zoom in/out and drag to pan across space to explore cluttered zones!