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LDN 158, 148, 152, 162, 163 - Ophiuchus

 

CLICK ON IMAGE FOR FULL SIZE VIEW (3989x2988)

Scope: Explore Scientific MN152 at f/4.8, Location: DAA Observatory, Shelter Valley, CA, 3 and 10 June 2021  Camera: ASI1600M (Astronomik Gen 2  LRGB Filters)

Exposure: Exposure: L - 64 x 4.5 minutes (gain-1700 1x1) ,  RGB - 20 each x 3 minutes  - (gain-139 1x1).

Processing: Data Collection -  Sequence Generator Pro (as FITs).  Sub-frame calibration - Pixinsight. Sub-frame  registration and integration (Average combine -  Winsorized Sigma Clipping) - PixInsight.  Mure Denoise - PixInsight. Non-linear stretching, normalization and gradient removal - PixInsight. Generation of starless nebulosity image (Luminance) - Star XTerrminator and Starnet2.  Curves, Levels, RGB combine, Luminance layering - PixInsight.  Final finishing  - Affinity Photo.  Photometric RGB calibration - PixInsight. Annotation - PixInsight, Aladin (Simbad and NED), and Affinity Photo. This image is a  LRGB with luminance layering. The monochrome starless was combined with a full monochrome image (two stops down in stretch) to minimize star bloat (using pixel math). Image processed at 4656x3520 resolution. Final Image size is approximately  3800x2850.

North is up in this image.  This image captures several Dark Nebulae that are faintly discernable due to limited star field and limited illumination of surrounding dust. The nebulae in this image are LDN 148, 152, 158, 162, 163 as well as a few others from the Dobashi and TGU catalogs. There is also a non-visible but IR detectable star 2MASS j16465480-1358175. This star has a high proper motion of 4,979 mas/yr - this compares with the highest proper motion known star (Barnard's Star) with a proper motion of 10,393 mas/yr. There are few with proper motions higher than 2MASS j16465480-1358175. High proper motion stars are characteristically relatively close (as an example, Barnard's Star is only about 6.8 light years distant). This means that the dark nebula obscuring it in visible wavelengths must be even closer. So this means the dust around the dark nebulae is  has  few stars to illuminate it. So the low contrast between the dark nebulae and the area around it make it hard to image in visible wavelengths. There are also two background galaxies that are visible through some of the light dust -  LEDA 926417 and 2MASS j16480313-1414517. These objects, information, and some of the brighter stars are identified in the annotated image. Horizontal FOV is approximately 85 arc minutes. Full size image scale is approximately 1.28 arcsec/pix.. 

Image center is approximately - Equatorial 2000: RA: 16h 48m 09s Dec: -14 14' 36"

 

 

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