Abell 21
Submitted: Mon, 2023-03-20 11:23
The Medusa Nebula is a planetary nebula in the constellation of Gemini. It is also known as Abell 21 and Sharpless 2-274. It was originally discovered in 1955 by University of California, Los Angeles astronomer George O. Abell, who classified it as an old planetary nebula. Until the early 1970s, the nebula was thought to be a supernova remnant. With the computation of expansion velocities and the thermal character of the radio emission, Soviet astronomers in 1971 concluded that it was most likely a planetary nebula.
SII = 22 * 1800 sec. bin1, Ha = 19 * 1800 sec. bin1, OIII = 17 * 1800 sec. bin1
Total 29 hours.
Pixinsight 1.8. 2017-2023 years.
