Gum 51 (Also catalogued as RCW 105) is an emission nebula in constellation Norma. The nebula is surrounded by numerous small molecular clouds and is likely embedded in the compact OB association R105. An estimated distance for the R105 association is about 1580 parsecs and its age is 12.8 million years. The Gum catalog is an astronomical catalog of 84 emission nebulae in the southern sky. It was made by the Australian astronomer Colin Stanley Gum (1924-1960) at Mount Stromlo Observatory using wide field photography. Gum published his findings in 1955 in a study entitled A study of diffuse southern H-alpha nebulae which presented a catalog of 84 nebulae or nebular complexes. Similar catalogs include the Sharpless catalog and the RCW catalog, and many of the Gum objects are repeated in these other catalogs. However, the RCW and Gum catalogs were mainly of the southern hemisphere (Mount Stromlo is in the southern hemisphere)

Telescope: Planewave CDK17 (FR) f4.5
Mount: Astro Physics 1600GTO
Camera: QHY16200A/ Integral FW
Guider: Agena Starguide II / SBIG STi

H-alpha: 88×10 mins = 880 mins

Total Imaging Time: 14h 40m

Data Imaged remotely over 3 nights during April 2021.
Imaged from Observatorio El Sauce, Chile, in partnership with Fred Espenak.
Data acquisition & Processing by David Churchill.

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