The Squid Nebula | Ou4

Posted on

Back to Targets

The Squid Nebula

Ou4 · Bipolar nebula · Cepheus · Possibly around 2,300 light-years from Earth

The faint blue Squid Nebula within the red glow of the Flying Bat Nebula, photographed from central Bristol.

TelescopeAskar 130PHQ

CameraZWO ASI2600MC Pro

SkyBortle 8

Integration64 hours

Captured10 May to 16 July 2026

Overview

This is the Squid Nebula, Ou4, hiding in the much larger red glow of the Flying Bat Nebula. It’s famously faint, especially in oxygen light, which made it an irresistible challenge from my city-centre back garden.

I’d photographed the Flying Bat and Squid together before with my wider-field Askar FRA400. This time I pointed the Askar 130PHQ at the Squid for a closer view. The project ran from 10 May to 16 July 2026 and added up to 64 hours of exposure. The short summer nights didn’t make that easy!

Background

I picked this target precisely because it’s such an extreme test from a city. My one-shot colour camera makes collecting data pleasantly simple, but the Squid was a reminder that convenience has its limits. Even after a very long integration, its oxygen signal was faint, and I had to work hard to bring it out.

Science

The blue structure is Ou4, a large bipolar nebula seen in the direction of the emission nebula Sh2-129, nicknamed the Flying Bat. The Squid stands out in light from doubly ionised oxygen, usually shortened to OIII, while the broad red background comes largely from hydrogen-alpha emission.

Its origin isn’t completely settled. A study of the gas and its motion found that Ou4 could lie within Sh2-129 and be an outflow associated with the star system HR 8119. If they’re at the same distance, we’re seeing them from roughly 2,300 light-years away. Other explanations for Ou4 haven’t been ruled out, so I’m keeping that distance approximate.

Imaging details

Dates
10 May to 16 July 2026
Location
Bristol, UK (Bortle 8)
Telescope
Askar 130PHQ Flatfield Astrograph
Camera
ZWO ASI2600MC Pro
Mount
StellarDrive X 6R PRO
Guiding
Askar M54 off-axis guider and ZWO ASI220MM Mini
Control
ASIAIR Plus
Processing
PixInsight and Lightroom
Image
Lee Pullen
FilterPurposeExposure
Optolong L-UltimateHα and OIII nebulosity744 × 300 seconds = 62 hours
Optolong L-Quad EnhanceRGB stars60 × 120 seconds = 2 hours

Optolong L-Ultimate

Hα and OIII nebulosity · 744 × 300 seconds · 62 hours

Optolong L-Quad Enhance

RGB stars · 60 × 120 seconds · 2 hours

Total exposure: 64 hours

Kit list

Affiliate links help support the site at no extra cost to you.

Processing

Most of the 64 hours came through the L-Ultimate, which records both Hα and OIII in one exposure. The hydrogen emission was there, but the OIII from the Squid was stubbornly faint. I had to boost that signal substantially during processing to make the shape stand out against the surrounding Flying Bat.

I still really like the relative simplicity of one-shot colour imaging. But for a target like this, I can see why a monochrome camera and a dedicated OIII filter would be a more sensible way to collect the faint oxygen signal. It’s one of those targets that makes me question my choices, just a little! I’ve written more about the trade-offs in OSC vs Mono from a City.

Processed monochrome green channel with the Squid’s faint oxygen signal brought forward.
Unedited monochrome green channel with the Squid Nebula barely visible.
OIII before processingOIII after processing

Subframes and stacks

Single two-minute L-Quad Enhance exposure of the Squid Nebula field.
L-Quad Enhance: one 120-second subframe.
Integrated L-Quad Enhance stack for the stars in the Squid Nebula image.
L-Quad Enhance: 60 × 120 seconds, totalling 2 hours.
Single five-minute L-Ultimate exposure of the Flying Bat and Squid region.
L-Ultimate: one 300-second subframe.
Integrated L-Ultimate stack of the faint Squid Nebula and surrounding hydrogen emission.
L-Ultimate: 744 × 300 seconds, totalling 62 hours.

Earlier views

Askar FRA400

My earlier Askar FRA400 image shows the Squid within the wider Flying Bat Nebula.

The Flying Bat and Squid Nebulae, Sh2-129 and Ou4, photographed with the Askar FRA400 from Bristol.
The Flying Bat and Squid Nebulae with the Askar FRA400.

Seestar S50

For comparison, here’s the Seestar S50 image from my earlier Flying Bat and Squid project.

Wide Seestar S50 view of the Flying Bat and Squid region from Bristol, with very faint nebulosity.
The Flying Bat and Squid region with a Seestar S50.

Explore more targets

Browse all targets →
The Flying Bat and Squid Nebulae photographed with the Askar FRA400The Flying Bat and SquidMy earlier widefield viewExplore target →Pickering’s Triangle photographed with the Askar 130PHQPickering’s TriangleAskar 130PHQExplore target →The Cygnus Loop photographed with the Askar FRA400The Cygnus LoopAskar FRA400Explore target →

Courses

Develop your photography with personal tuition, including an online Urban Astrophotography Masterclass.

Explore courses →

Art Store

Bring the night sky into your home with a fine art print.

Visit the Art Store →

Stay updated

New photographs, practical guidance, and reviews, as the projects unfold.

Subscribe for updates →
InstagramFacebook

Support

If you find the site useful, a donation helps with keeping it running.

Donate

Discover more from Urban Astrophotography

Subscribe to get the latest posts sent to your email.

Leave a Reply

Your email address will not be published. Required fields are marked *