IC 1795 (NGC 896) Fish Head Nebula
OTA: RCOS (14.5” f/8)
Camera: SBIG STX-16803
Observatory: Deep Sky West
EXPOSURES:
Hydrogen: 34 x 1800 sec
Sulfur: 27 x 1800
Oxygen: 31 x 1800
Total exposure ~46 hours
Image Width: ~1/2 deg
Processed by Alex Woronow using PixInsight & ON1 in 2018
The Narrow-Band Image: Not much has been written about this object. We know it lies at about 6,000 light-years distance, and spans about 70 light-years. Current speculations hold that the gasses of the nebula are excited by very young, hot stars (a few million years old) forming within the nebula, but still out of sight. The are hidden in their natal clouds of gas and dust.
Processing: This image is all in narrow-band emissions: Hydrogen Alpha, Oxygen III and Sulfur II. Images taken in narrow bands such as these usually are mapped to Red/Blue/Green by a variety of schemes. The Pallet is one suggested by Juan Conejero (
https://pixinsight.com/forum/index.php?topic=2513.0).
The H-Structure Image: Image processing textbooks frequently mention sharpening by the Laplacian of Gaussian (LoG) method. That was used here on the unstretched Hydrogen image before combining the HSO stacks.
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