Sharpless 261

In 1959 U.S. astronomer Stewart Sharpless published a catalog of 312 Hydrogen-ii emission nebulae. This is number 261, a faint nebula in the constellation Orion. Also known as Lower's Nebula, it is named after father and son Harold and Charles Lower who discovered it photographically in 1939.


Exposure  • 12 hours (72 X 10 minutes) @ -20°C
   ☞ 24 full color
   ☞ 48 with Hα filter
 • Dusk flats
 • Camera position angle: 0°
Processing  • With PixInsight:
   ☞ Calibrate, star-align, integrate subframes
   ☞ Histogram transformation
 • Noise reduction with Topaz DeNoise AI
 • Ffinal tweaking and sizing in Photoshop CS6
Date and Location  • November 20 & 28, 2022
 • Louisa County, Virginia, USA
Equipment
 • TMB-130SS APO refractor @ f/7 on an A-P 1200 mount
 • ZWO ASI-1600MC Pro color camera
 • Guided with a ZWO ASI-120M camera on a 60mm f/5 scope
 • Imaging and autoguiding with MaxIm DL 6.20
 • Automated image acquisition with ACP Observatory Control


Updated May 23, 2023