Sh2-86, NGC 6820, 6823, Kronberger 9 (PN)
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ON IMAGE FOR FULL SIZE VIEW (4029x6137)
Scope:
FSQ-106N at f/5, Location: DAA Observatory, Shelter
Valley, CA; 12 and 20 May and 13 June, 2023, Camera: ASI2600MM (Astronomik
type 2c RGB, 6 nm Ha, OIII filters) Exposure:
Exposure: Ha - 67 x 3.5 min (gain-160 1x1), OIII - 61 x 3.5 min (gain-180
1x1) , RGB -24 x 2 min (gain-101 1x1) each RGB exposures. Processing: Data
Collection - N.I.N.A. Sequencer (as FITs). Sub-frame calibration -
Pixinsight (WBPP). Sub-frame registration and integration (Average combine
- ESD rejection) - PixInsight (WBPP). Mure Denoise - PixInsight.
Non-linear stretching, normalization and gradient removal - PixInsight.
Photometric RGB calibration (SPCC) - PixInsight. Deconvolution of Ha OIII and
RGB- BlurXTerminator. Generation of starless nebulosity Ha, OIII, and RGB images
for later processing - Star XTerminator. Curves, Levels, RGB combine,
Range Compression - PixInsight. RGB Stars and Narrow Band / Wide Band
Starless combine - PixInsight. Final finishing -
Affinity Photo. Annotation - PixInsight, Aladin (Simbad and NED),
and Affinity Photo. This image is a Bicolor Narrow Band starless image
(modified HOO) and starless Wide Band image combined to make the
starless composition - with RGB stars then added. Image processed at
6248x4176 resolution. Final Image size is approximately 4029x6137. The above image is
a landscape crop of the full size portrait image (north up). This
image shows the region centered about Sh2-86 (also known as LBN 135) and the
associated open cluster NGC 6823. This open cluster is about 7,313 light
years distant (by parallax). Just to the southeast (lower left) is a small but
colorful planetary nebula (Kronberger 9). To the southwest is NGC 6820 (galactic
nebula) which in the past has been identified with the larger emission
structure to the southwest, but more recently designated (by the
NGC/IC project and others) to be the smaller bright flare nebula at the same
central coordinates. Coincident with these coordinates is the very small
open cluster Collinder 404. Other notable emission structures (one above and
another to the right of Sh2-86) appear in a lesser known catalog as Du 28 and Du
26 (HII regions of the Northern Milky Way - R. Dubout-Crillon 1976). There
are several Dark Nebula from the TGU Catalog (optical, by star count method) and
the Dobashi catalog (IR Band - 2MASS sky survey). These objects and
some of the brighter stars are identified in the annotated
image. This image replaces an earlier
image that can be seen in the Archives
here. Vertical
FOV (of Full size image) is approximately 149 arc minutes. Full size image scale
is about 1.46 arcsec/pix. Image
center is approximately - Equatorial 2000: RA: 19h 43m 09s Dec: +23°17'41"
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