NGC 246

These photos were taken on Prompt 6 and Prompt 7 from October 27, 2024, to November 2, 2024.

This is a natural-color photo of NGC 246, a planetary nebula that will eventually become a white dwarf. It may have been a sun-like star, which means that it could be an example of what our sun could look like after billions of years.

We first remove dead pixels with the Afterglow Cosmetic Correction tool to stack the images by filter. Then, we remove any bad images. This includes images where the telescope's tracking failed and/or images that contain ghosts.

After removing the bad images, we mapped them with WCS to align them. Then, we stacked them by filter. Those stacked images are shown below.

The test photos that didn't contain errors were included in the process.

To colorize the photos, I made the Halpha, OIII, SII, and Lum images invisible. I linked the display settings to the Luminance layer and set R to appear red, B to appear blue, and V to appear green. I then went through the photometric calibration of Skynet, set the white balance reference object to the black body peaking in V filter. I set the stretch mode to midtone. I set the E(B-V) to 0.02.

Then the luminance layer was made visible and the blend mode was set to luminosity so that the gray color does not wash-out the color. Due to the luminance layer's degradation of the details in the photo, it was turned off. This degradation was likely due to noise.

Halpha has emission lines at 656nm(red), 486nm(blue-green), 424nm(violet-blue), and 410nm(violet). These emission lines appear a specific colors of wavelength. This make Halpha appear pink (Balmer pink). So for the Natural photo, the color of the Halpha layer was set to Balmer. The blend mode was set to lighten.

OIII has emission lines at 501nm (blue-green) and 496nm (blue-green). This makes OIII appear blueish-green. So for the Natural photo, the color of th eOIII layer was set to Blue-Green. The blend mode was set to lighten.

SII has emission lines at 672nm (red), and 673 (red). This makes SII appear red. So for the Natural photo, the color of the SII layer was set to Red. The blend mode was set to lighten.