NGC 2467 "The Skull and Crossbones Nebula"

NGC 2467, colloquially known as the “Skull and Crossbones Nebula”, is a vibrant and active star-forming complex situated in the southern constellation of Puppis. First discovered by William Herschel in 1784, this extensive H II region is catalogued under several designations, including Sh2-311, Gum 9 and RCW 16. It lies at an estimated distance of roughly 15 000 light-years from Earth (although values quoted in the literature range between approximately 13 000 and 20 000 light-years depending on the stellar populations considered and the measurement method), placing it within one of the outer spiral arms of the Milky Way.

The nebula is composed predominantly of ionised hydrogen. The presence of doubly ionised oxygen (O III) in higher-excitation regions provides additional structural contrast and contributes to its varied colour appearance. Its distinctive appearance is shaped by intense ultraviolet radiation and stellar winds from young, massive stars, most notably the O-type system HD 64315, a multiple massive star that acts as the principal ionising source for the surrounding H II region. The energetic output of these stars has carved out a central cavity that forms the “eyes” of the skull-like structure. The region is not a single physical cluster but rather a complex line-of-sight superposition of several young open clusters embedded within the nebula.

The internal dynamics of NGC 2467 are highly active. Radiation pressure and stellar winds from newly formed stars interact with dense molecular material, producing bright ionisation fronts, dark dust lanes and pillar-like structures often referred to as “elephant trunks”. Infrared observations, particularly from the Spitzer Space Telescope, have revealed numerous protostars and young stellar objects located along these ionisation fronts. These findings indicate ongoing star formation and suggest that stellar feedback may be influencing the birth of subsequent generations of stars. With embedded clusters estimated to be only a few million years old, NGC 2467 remains a representative example of a high-luminosity stellar nursery.

Image Acquisition

NGC 2467 is not an easy target from the latitude of my observatory in Àger, as it rises to a maximum altitude of only 22° above the southern horizon.

Although the nebula is by no means faint, an unusual succession of poor weather conditions over recent months prevented me from obtaining the total exposure time I had initially planned. During November - December 2025 and February 2026, I was able to collect 18 Hα sub-exposures of 30 minutes each, but only 14 sub-exposures in O III and 16 in S II.

All data were acquired remotely. The narrowband images were taken with my Takahashi TOA-150 refractor equipped with an SBIG STL-11000M CCD camera. The RGB star data were obtained with the Takahashi FSQ-106N. I used an Astrodon filter for Hα and Baader filters for O III, S II and RGB.

The total integration time of narrowband data amounts to 24 hours.

Image Processing

The processing strategy for this image was based on removing the stars from the linear datasets using StarXTerminator, allowing the narrowband nebular structures and the RGB stellar component to be processed independently.

The starless nebula image was mapped using both an HOO (First image on the right) and an HSO (second image) palette and then fully processed in PixInsight.

For the HSO version, I followed the method described by Adam Block. In essence, the process consists of initially developing the image in an HOO palette and subsequently introducing a colourised S II layer to enhance the sulphur contribution and achieve a more balanced chromatic result.

Regarding the remainder of the processing workflow, I would particularly highlight the use of the new PixInsight tool MultiscaleAdaptiveStretch, which produced very satisfactory results in controlling contrast while preserving faint structures.

In these images, North is left.

Click on the images for full resolution versions, or visit the Gallery section for complete exposure details.

Image processing: Pixinsight.

Observatory automation and remote operation:  Talon6.