SH2-274 Medusa Planetary Nebula

SH2-274 Medusa Planetary Nebula
February 6, 2025
Zionsville, IN, Bortle 6-7
SVBONY SV550 APO 80 mm'
ZWO AM 5, ASIAIR plus, Guided
Antlia ALP-T Dual Narrowband Filter
ASI2600 MC PRO
Gain 100, -10C, darks, flats, bias
153 lights each 180 sec, total 7.65 hrs
Wikipedia:
The Medusa Nebula is a planetary nebula in the constellation of Gemini. Distance ca. 1,500 ly. 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.[4] 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.[4] As the nebula is so large, its surface brightness is very low, with surface magnitudes of between +15.99 and +25 reported.[citation needed]
The central star of the planetary nebula is an PG 1159 star.[5]

Sh2 274 Image09 Enh