Acquisition Dates: Captured over 2 seasons 2022-23
2022 Feb 18, 20, Mar 02
2023 Jan 09, 10, 15, 16, 27, 28, Feb 13, 19
Frames -- All gain 100, -10°C, bin 1x1:
Ha: 194x300" (16h 10m)
OIII: 183x300" (15h 15m)
R: 75x60" (75m)
G: 70x60" (70m)
B: 77x60" (77m)
Integration: 35h 07'
Bortle Dark-Sky Scale: 4
Sh2-261 (aka Lower's Nebula or Sharpless 261) is an emission nebula in the northern region of Orion. The Lowers (father and son) were amateur astronomers and found this nebula on one of their photographic plates taken in 1939. There is a wide range of estimates of the distance to this nebula, the most accepted one being about 3.300 light years.
The nebula image was captured with narrowband Ha and OIII filters and post-processed into a synthetic RGB color palette. Broadband RGB filters were used to capture star data which was blended into the starless narrowband image.
ADDENDUM 13 May 2023
Upon closer examination of the image, I serendipitously noticed the faint and small (0.2 arc min diameter) planetary nebula candidate Cop 3 (HASH catalog designation PN-G: 194.0-00.5) which is shown magnified in the attached crop.
The area from where this crop is taken is shown below.
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