StDr56, also catalogued as PN G141.8−29.9, is a planetary nebula in the constellation Triangulum. Its distinctive shape and flame-like filaments earned it the nickname “Goblet of Fire”. Discovered in January 2020 and first published that December, it lies at an unusually high galactic latitude, in a field threaded with faint integrated flux nebula (IFN).
Much about StDr56 remains uncertain, including its age and expansion rate. Two possible central stars have been identified, with estimated distances of around 1,130 and 3,800 light-years respectively, so the nebula’s distance has yet to be firmly established. Its unusual morphology, surrounding dust, and relatively small number of deep amateur images made it a compelling target for the Deep Sky Collective.
The project
We began imaging StDr56 in November 2025, collecting data over roughly three months, followed by several months of stacking and processing. Twelve contributors worked across coordination, photography, stacking, and editing, with several taking on multiple roles.
The total integration reached 342 hours and 55 minutes, with approximately 100 hours each in H-alpha and OIII. Broadband LRGB data captured the surrounding IFN and supported continuum subtraction, helping separate the nebula’s emission from the background stars and continuum light.
We also collected SII to investigate whether it could contribute to the image. Signal was present, but too faint to incorporate into the final edit. A deeper SII acquisition could be worth exploring in a future project. The published image combines LRGB, H-alpha, and OIII data.
What the data revealed
Our aim was to explore StDr56’s fine structure with sufficiently deep data to preserve faint detail without relying heavily on noise reduction.
The H-alpha data revealed the full shell in detail, together with broad striations across the background. Although we did not identify any new structures around the nebula, the combined dataset offers a clearer view of its delicate filaments and the relationship between its H-alpha and OIII emission.
One notable feature is the softness of the filamentary structure. Even with this depth of integration, parts of the nebula retain a diffuse appearance—a characteristic that careful processing aimed to preserve.
Two versions
The dataset was processed independently by Nicolas Puig and me. The image presented here is my interpretation, with Nicolas’ version offering an alternative treatment of the same data.
Integration
H-alpha: approximately 100h / OIII: approximately 100h / Additional data: LRGB and SII / Total collected: 342h 55m
SII was not included in the final image.
Credits
Tim Schaeffer: coordination and photography
Adrien Keijzer: stacking
Steeve Body and Nicolas Puig: image processing
Additional photographers: Akash Jain, Alpha Zhang, Carl Björk, Jasper Capel, Jeff Schilling, Jim Matzger, John Dziuba, and Stephen Guberski.
Explore the full-resolution image in the Deep Sky Collective gallery.