Astro Anarchy: Sharpless 155, the Cave Nebula

Thursday, April 10, 2025

Sharpless 155, the Cave Nebula

This is one of the targets I’ve been imaging for decades using various equipment—from camera lenses (150–300mm) to large reflecting telescopes ranging from 11" to 14". (My older photos can be seen at end of this blog post)

This time, I used new imaging setup to capture a high-resolution image of Sh2-155.
The seeing conditions weren’t ideal, but I’m fairly happy with the results.

Sharpless 155 (Sh2-155), the Cave Nebula

Click for a large image, 2000 x 1900 pixels

A mapped color image from a light emitted by an ionized elements, sulfur=red, hydrogen=green and oxygen=blue. Original resolution 6500 x 5500 pixels

Sharpless 155 in Visual Palette

Click for a large image, 2000 x 1900 pixels

Visual color version of Sh2-155 glows mostly in red from a light emitted by an ionized elements,
sulfur=red, hydrogen=red and oxygen=blue, this combination is very close to a natural color palette.

Info

Sh2-155—also known as Caldwell 9, Sharpless 155, S155, or LBN 529—is a diffuse nebula located in the constellation Cepheus. It lies within a larger nebula complex that includes emission, reflection, and dark nebulosity. It’s widely known as the Cave Nebula. (Note: The reflection component is not visible in my narrowband image.)

The nebula is approximately 2,400 light-years away. This photo covers an area of about 0.7 × 0.7 degrees of the sky—for reference, the full Moon has a diameter of 0.5 degrees, or 30 arcminutes.

Technical details

Processing workflow

Image acquisition, MaximDL v6.5

Stacked and calibrated in CCDStack2.

Deconvolution with a CCDStack2 Positive Constraint, 27 iterations, added at 50% weight

Color combine in PS

Levels and curves in PS

Imaging optics,

Celestron EDGE 14" with 0.7 Focal reducer

Mount,

MesuMount Mark II

Cameras,