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The OU4 Squid Nebula is one of the most unusual and enigmatic objects in the night sky. Discovered in 2011 by French astrophotographer Nicolas Outters, OU4 is a vast, ghostly cloud of ionized oxygen located in the constellation Cepheus. Its distinctive shape—resembling a giant, bi-lobed squid with long, flowing tentacles—has made it a favorite target among deep-sky imagers.
Unlike most nebulae, the Squid Nebula shines almost exclusively in doubly ionized oxygen (O III) light, giving it an ethereal blue glow and making it nearly invisible in broadband images. Spanning an enormous area of sky—several times larger than the full Moon—OU4’s true physical size remains uncertain due to ongoing debate about its distance.
The nebula appears projected against the bright SH2-129 Flying Bat Nebula, but it is not physically related. Its origin is still a mystery; leading theories suggest it may be the result of an ancient, powerful outflow from a massive star or a highly energetic event that sculpted the surrounding interstellar medium.
The OU4 Squid Nebula stands as a reminder that the deep sky still holds surprises—faint, fragile structures that challenge our understanding and reward patient observation with haunting beauty.
Technical Details
Telescope: Sky-Watcher Esprit 100ED Refractor
Auto Focus: ZWO Electronic Auto Focuser
Astronomy Camera: ZWO ASI071MC Pro
Filter: Antlia ALP-T Dual Narrowband Ha/Oiii Filter; 1200 exposures @ 5 minutes each (100 hours)
Total Integration Time: 100 hours
Auto Guiding: William Optics Uniguide 50mm Guide Scope
Auto Guiding Camera: ZWO ASI120MM Mini Guide Camera
Auto Guiding Software: PHD2
Telescope Mount: Sky- Watcher EQ6-R Pro Equatorial Mount
Telescope Computer: BeeLink GK-55 Mini PC / Windows 10 Pro
Wireless Communication: GL-iNEt Beryl Travel Router
Telescope Control & Image Capture Software: Nighttime Imaging ‘N’ Astronomy (N.I.N.A.)
Image Integration Software: Astro Pixel Process, by Aries Productions
Image Post Processing Software: PixInsight, by Pleiades Astrophoto
Images captured: Palm Springs, CA during September 2022. Dark sky classification = Bright suburban sky (Bortle 6)