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Lower's Nebula Sh2-261



Scope: FSQ-106N at f/5, Location: DAA Observatory, Shelter Valley, CA, 28 December 2019 and 22 January 2020,  Camera: Atik 383L (Astronomik Gen 2  Ha, OIII , RGB Filters)

Exposure:  18 x 12 min (1x1 bin) Ha filter, 24 x 12 min (2x2 bin) OIII  filter, 8 x 5 min (1x1 bin) each RGB filters.

Processing: Data Collection -  Sequence Generator Pro (as FITs).  Subframe calibration and registration - PixInsight. Subframe integration (Median combine -  Winsorized Sigma Clipping) - PixInsight.  Non-linear stretching, normalization and gradient removal - PixInsight.  Generation of starless nebulosity images - starnet++.  Starless color mapping (modified HOO mapping) and RGB stars color - PixInsight. Stars and Starless combine - PixInsight. Final finishing  - Photoshop.  RGB calibration - eXcalibrator. Annotation - PixInsight, Aladin (Simbad), and PhotoShop. This image is a  modified HOO narrow band mapping with RGB stars.  Images processed at 3354 x 2529 resolution. Final Image size is approximately  3000x2250.

North is up in this image.  This is an image of the emission nebula Sh2-261 (known popularly as Lower's Nebula and also known as LBN 863, SIM 34). Embedded within Sh2-261 is LBN 862 and LBN 864.  Also there are several dark nebulae in this field (Dobashi 4665, TGU H1364 P13, TGU H1364 P14) and one open cluster ([KPS2012] MWSC 0725).  These objects and some of the brighter stars are seen in the annotated image.  The horizontal FOV is approximately 120'. Image scale of the full size image is 2.4 arcsec/pix. 

Image center is located approximately - Equatorial 2000: RA: 6h 08m 46s Dec: +1548'39" 


All images and content remain the property of Jim Thommes - copyright 2003 - 2020

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