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NGC 281 - "Pac Man"



Scope: Celestron 9.25 Edge HD 235 mm at f/7; Location: DAA Observatory, Shelter Valley, CA;  Dates:  16, 22 August, 8, 15 September 2023; Camera: ASI294MM (Baader  Ha OIII RGB Filters)

Exposure: Ha 85 x 4 minutes (gain-160 2x2) ,  OIII 83 x 4 minutes (gain-160 2x2), RGB - 40 each x 2 minutes  - (gain-121 2x2).

Processing: Data Collection -  N.I.N.A. (as FITs).  Sub-frame calibration - Pixinsight (WBPP). Sub-frame  registration and integration (Average combine -  Winsorized sigma clipping,  2X drizzle) - PixInsight (WBPP).  TGV Denoise (RGB) and MMT  (Ha, O3) - PixInsight.  Non-linear stretching for Ha and OIII - PixInsight.    RGB combine and stretching, Photometric RGB calibration (SPCC)  - PixInsight. Generation of starless Ha, OIII, and RGB image for later processing - StarXTerminator  (PixInsight.)  De-convolution - BlurXTerminator (AI4) - PixInsight.  Ha and OIII color mapping is a modified HOO palette of the starless stacks - PixInsight.  RGB star image is screened into the Haand O3 narrow band starless construction - Pixinsight. Final finishing  - Affinity Photo.  Annotation - PixInsight, Aladin (Simbad), and Affinity Photo. This image is a  modified HOO mapping with RGB stars.  Image processed at 8288x5644 resolution (2x drizzle stacks). Final crop Image size is approximately 4208x6184.


North is up in this image - it is a close up of  NGC 281- the "Pac Man" nebula. NGC 281 is also known as Sh2-184, LBN 616, and Cederblad 3. It is an emission nebula structure  with most of the Ionization energy coming from the multiple star HD 5005 (five component parts). Component parts are HD 5005 A through E.  Parts A and B are indistinguishable in this image data acquisition -  catalog separation is 1.5 arc seconds.  Other Parts can be discerned  apart from the HD 5005 AB  pair. Distance of NGC 281 is about 9,190 light years.  The open star cluster  IC 1590 is at the center of the emission structure  - it has 107 members or probable members. IC 1590 central distance is about 9,620 light years. The HD 5005 component parts are cluster members. The prominent dark nebula at the lower part of the emission structure is Dobashi 3745; just below that is the separate fainter HII structure of LBN 615.  These objects, information, and some of the brighter stars are identified in the annotated image.  There is an earlier HaLRGB  image of NGC 281 taken in 2016. The Vertical FOV is approximately 40.1 arc minutes. Full size image scale is approximately 0.389 arcsec/pix.

Image Center approximately - Equatorial 2000: RA: 0h 52m 56s Dec: 5637'40"


All images and content remain the property of Jim Thommes - copyright 2003 - 2024

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