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NGC 6232, 6236, 6248 - A Galaxy Trio



Scope: Celestron 9.25 Edge HD 235 mm at f/7, Location: DAA Observatory, Shelter Valley, CA, 22 and 25 June 2022,  Camera: ASI294MM (Baader  LRGB Filters)

Exposure: L - 73 x 4 minutes (gain-121 2x2) ,  RGB - 20 each x 2.5 minutes  - (gain-121 2x2).

Processing: Data Collection -  Sequence Generator Pro (as FITs).  Sub-frame calibration - Pixinsight (WBPP). Sub-frame  registration and integration (Average combine -  Winsorized Sigma Clipping) - PixInsight (WBPP).  Mure Denoise - PixInsight.  Non-linear stretching, normalization and gradient removal - PixInsight.   Curves, Levels, RGB combine, Luminance layering - PixInsight. Generation of starless Luminance image for later processing - StarXTerminator. Photometric RGB calibration (SPCC) - PixInsight.  De-convolution - BlurXTerminator.  Final finishing  - Affinity Photo.  Annotation - PixInsight, Aladin (Simbad and NED), and Affinity Photo. This image is a  LRGB with luminance layering.  Image processed at 4144x2822 resolution. Final Image size is approximately  3952x2753.

North is to the right in this image.  This image shows a trio of spiral galaxies, NGC 6232, NGC 6236, and NGC 6248. The upper two galaxies NGC 6236 - SAB(s)cd, and NGC 6248 - SBd, are a pair in a group ([TSK2008] 818 group).  They are very similar in radial velocity, redshift,  and distance estimates  (both redshift and Tully Fisher estimates). These galaxies have a low radial velocity of about 1,200 to 1,300 km/sec. As such, the redshift distances are lower than their Tulley-Fisher estimates (51-58  million light years by redshift vs. 76-77 million light years by Tulley-Fisher).  NGC 6232 - (R')SB(s), is sort of the opposite with a high radial velocity (about 4,440 km/sec) and has a higher redshift distance estimate than the Tullley-Fisher (202 million light years by redshift vs. 58 million light years by Tully-Fisher). This region is otherwise relatively lightly studied.  There are numerous background galaxies that can be seen in the full size image but most only have IR or UV source designations in 2MASS, GALEX, or WISE.  The furthest objects are a few Quasars or Quasar Candidates and their distances range from 3.49 to 10.56 billion years (Lookback).  These objects, information, background galaxies, and some of the brighter stars are identified in the annotated image Horizontal FOV is approximately 38.75 arc minutes. Full size image scale is approximately 0.59 arcsec/pix.

Image Center approximately - Equatorial 2000: RA: 16h 44m 50s Dec: +7033'42"


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