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Sh2-303, Sh2-308 "Dolphin Head"



Scope: FSQ-106N at f/5, Location: DAA Observatory, Shelter Valley, CA,  Dates: 15, 18, 20 Feb 2023, 16 Mar 2023, 2, 8, 12, Dec 2023,  Camera: ASI2600MM (Astronomik type 2c Ha, OIII, RGB filters)

Exposure: Exposure:  Ha 92 x 4 min (gain-240 1x1), OIII 92 x 4 min (gain-240 1x1), RGB 24 x 2 min (each - gain-101 1x1)  for each panel.

Processing: Data Collection -  Sequence Generator Pro (Feb / Mar sessions), N.I.N.A. (Dec sessions) - as FITs.  Sub-frame calibration - Pixinsight (WBPP). Sub-frame  registration and integration (Average combine - Winsorized Sigma Clipping) - PixInsight (WBPP).  Mure Denoise - PixInsight. Deconvolution - BlurxTerminator (via PixInsight). Non-linear stretching and gradient removal - PixInsight.  Generation of starless nebulosity Ha and OIII images for later processing - Star XTerminator.  RGB combine, RGB stretching, SpectroPhotometric RGB calibration (SPCC) - PixInsight. Mosaic By Coordinates and Gradient Merge Mosaic - PixInsight.  Final finishing  - Affinity Photo. Annotation - PixInsight, Aladin (Simbad), and Affinity Photo. This image is a narrow band HOO image  with RGB stars. Image panels  processed at 6248x4176 resolution. Final Mosaic Image size is approximately  7868x6121.

North is left in this image.  This is a two panel mosaic image. It shows the region around Sh2-303 and Sh2-308 (also known as the "Dolphin Head Nebula"). Sh2-303 is the emission nebula on the left and Sh2-308 is on the right. Both of these emission objects are ionized by the Wolf-Rayet star WR 6 - approximately in the middle of Sh2-308.  Also in this image are the small bright planetary nebula PNG 233.0-10.1 and the large dim planetary nebula PNG 234.9-09.7 - the latter located right at the lower edge of Sh2-308 in this image. The open cluster Berkeley 75 is at the top edge of this image - its distance is about 37,000 light years. There are also a number of background  galaxies that can be seen n the full size image (at full zoom). A visible quasar is seen near sh2-303 - WISEA j065440.34-220321.0 with a 5.052 billion year light travel time. These objects and some of the brighter stars are identified in the annotated image.   Horizontal FOV is approximately 3.21 degrees. Full size image scale is about 1.47 arcsec/pix.

Image center is located approximately - Equatorial 2000: RA: 06h 54m 14s Dec: -2307'20"


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

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