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Contains:  NGC 1931
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The Fly (NGC1931)

Technical card

Resolution: 2013x1441

Dates:Dec. 1, 2019Jan. 2, 2020Feb. 2, 2020

Astrodon I-series: 60x480" bin 2x2
Astrodon I-series: 36x6" bin 2x2
Ha 5nm: 76x900" bin 1x1

Integration: 27.1 hours

Avg. Moon age: 6.47 days

Avg. Moon phase: 40.70% job: 3233170

RA center: 5h 31' 20"

DEC center: +34° 13' 22"

Pixel scale: 0.511 arcsec/pixel

Orientation: 290.878 degrees

Field radius: 0.176

Data source: Backyard


The object commonly known as “The Fly” is the combination of a red emission nebula, blue reflection nebula, and an open star cluster. The star cluster is listed in the New General Catalog (NGC) as NGC 1931, while the nebulosity is included in the Sharpless catalog as Sh2-237. NGC 1931 is located in an extension of the Perseus Arm of the Milky Way about 7000 light-years away. The stars are relatively young at an age of about 10 million years. A study by A.K. Pandey and H.S. Mahra suggests the nebulosity may be a background object to the star cluster (

The Fly is often imaged in a wide field view with “The Spider” nebula (IC 417) which appears much larger and dominates the field. I have always admired the compact cocoon-like shape of The Fly and chose to highlight its unique features.

I hope you enjoy!



License: None (All rights reserved)

Sky plot

Sky plot


The Fly (NGC1931),