A Seagull in Space
On the night of March 9, 2026, I imaged the Seagull Nebula (IC 2177 / Gum 2 / Sh2‑296), a large H II emission and reflection nebula complex located along the Monoceros–Canis Major boundary. This wide‑field frame was captured from Eden, New York, and encompasses approximately a 7.5° × 3.5° field of view, including the nebular structure of IC 2177 as well as several associated open clusters, most notably Messier 50 (NGC 2323). The Seagull Nebula is part of the larger Canis Major R1 star‑forming region and is well suited to wide‑field, narrowband imaging due to its extensive hydrogen emission and low surface brightness.
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| The Seagull Nebula (IC 2177 / Gum 2 / Sh2-296) captured with my wide-field astrophotography rig from my backyard on 3/9/2026. |
What is it? How big is it? How far away is it?
This annotated wide‑field frame centers on the Seagull
Nebula (IC 2177 / Gum 2 / Sh2‑296), a large H II / reflection complex captured from my backyard
on 3/9/2026, with several open clusters (notably M50 / NGC 2323) and smaller
NGC clusters visible across the ~7.5° × 3.5° field.
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| An annotated image highlighting notable objects found within the field of view. |
Seagull Nebula — IC 2177 (Gum 2 / Sh2‑296)
Type: H II
emission + reflection nebula complex. Key fact: the region forms the
“head and wings” that give the Seagull its name; ionized hydrogen and
reflection from dust produce the bright structure in wide‑field images. Context:
IC 2177 straddles the border of Monoceros and Canis Major and is part of a
larger star‑forming complex (CMa R1).
M50 — Messier 50 / NGC 2323
Type: Bright open cluster (Messier object). Key
facts: apparent magnitude ~5.9, distance ≈ 2,800–3,000 light‑years,
and a compact, visually striking cluster often called the “Heart‑Shaped
Cluster.” In your frame M50 provides a dense stellar contrast to the diffuse
nebula.
NGC 2335
Type: Open cluster in the Seagull region. Key
facts: moderately faint (visual mag ~7–7.8) and small on the sky (a few
arcminutes across); it sits close to the nebular clouds and is often included
in wide‑field mosaics of IC 2177. Use it as a positional anchor when
identifying the eastern wing.
NGC 2343
Type: Open cluster. Key facts: visual mag
~6.7, angular size ~7–8′; appears as a compact grouping of stars embedded
against the nebular background and helps mark the central portion of the
Seagull complex in wide‑field views.
NGC 2353
Type: Young open cluster on the eastern edge of the
CMa OB1/Seagull region. Key facts: visual mag ~7.1 and angular size
~15–20′; it is a loose but noticeable cluster that often appears in wide‑field
images of this area and contributes to the “stellar scaffolding” around the
nebula.
NGC 2318
Type: Smaller open cluster (fainter and more compact than M50). Key facts: angular size a few arcminutes; one of several lesser clusters in the field that, together with the larger NGC objects and M50, illustrate the region’s clustered star formation and line‑of‑sight richness.
How to find it?
The Seagull Nebula is located in the constellation Monoceros but is close to the border of the constellation Canis Major. Monoceros lacks bright stars, making traditional star-hopping difficult in this region. The object is located 7.5 degrees north of Sirius, the brightest star in the night sky. Dark skies, a wide field telescope, and nebula filter will help to see this object visually. The area is rich with deep-sky objects, including several open clusters such as M46, M47, and M50, either within the field or nearby.
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| A finder chart for the Seagull Nebula |
Imaging Notes:
Monday, March 9th, was the second clear night in a row, with my wide‑field astrophotography rig still set up from the previous evening. Sunday’s imaging session will be covered in a separate post. Although we had just set the clocks ahead for Daylight Saving Time, it still became dark early enough to allow for a reasonable imaging session. My goal was to collect a couple of hours of data and be finished between 11:00 PM and midnight.
I selected the Seagull Nebula as my target for the night. As an emission nebula with extensive hydrogen structure, it is well suited to narrowband imaging, so I used a dual narrowband filter (Optolong L‑eXtreme). This filter isolates two 7 nm band passes centered on Ha and O iii, effectively suppressing broadband light pollution. The Moon rose after my imaging session and did not interfere with data collection. With uncertain weather ahead and limited clear nights this winter, I chose to capture this target while conditions allowed. The Seagull Nebula has been on my imaging list for some time, but persistent poor weather over the past few winters had delayed the opportunity.
Processing:
The following outlines my complete PixInsight workflow, from calibration through final integration.
Pre-Processing:
- All subs were visually inspected with Blink and subs with issues were removed.
- All light Frames, Flats, Darks and Dark flats were loaded into WBPP.
Linear Post Processing:
- Background extraction was performed with GraXpert
- BXT (correct only)
- SPCC was used for Color Calibration
- Full application of BXT
- Noise was reduced with NXT
- The image was made non-linear with MAS
Non-linear Post Processing:
- The Stars were removed using StarXT
Starless:
- Narrowband normalization process in mode 1 was used to get the "SHO look"
- Color, intensity, and contrast were adjusted with various applications of CT
- Saturation was increased with CT
- The Image blend Script was used to sharpen the image with a High Pass Filter
Stars:
- Saturation was increased with CT
- SCNR was applied
- The Correct Magenta Stars Script was used to help with stars captured with a dual narrowband filter
Final:
- The Stars and Starless images were combined with Pixel Math to produce the final image
- CT was used to adjust contrast one last time
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