2025-09-03, 06:45 PM
Hello,
Here is some information about how SkyTools calculates the visibility of dark nebulae, which may help. Surface brightness is not a consideration.
The detectability of a dark nebula is defined by how the dark area contrasts with the stars around it. If you see few stars, the nebula will be difficult to discern. As you increase the number of stars you can see, usually because you are seeing fainter stars, the nebula will be more easily visible. So if there is less light pollution or a larger aperture telescope, you will see fainter stars, and the dark nebula will be more easily detectable.
What I did was to view each dark nebula and then assign a star magnitude limit to each detectability range: obvious, easy, perceptible, difficult, challenging, very challenging. SkyTools calculates the faintest star you can see at a given moment in your telescope from your location and that is used to determine the detectability (easy, difficult, etc).
No outside catalogs or are required.
Here is some information about how SkyTools calculates the visibility of dark nebulae, which may help. Surface brightness is not a consideration.
The detectability of a dark nebula is defined by how the dark area contrasts with the stars around it. If you see few stars, the nebula will be difficult to discern. As you increase the number of stars you can see, usually because you are seeing fainter stars, the nebula will be more easily visible. So if there is less light pollution or a larger aperture telescope, you will see fainter stars, and the dark nebula will be more easily detectable.
What I did was to view each dark nebula and then assign a star magnitude limit to each detectability range: obvious, easy, perceptible, difficult, challenging, very challenging. SkyTools calculates the faintest star you can see at a given moment in your telescope from your location and that is used to determine the detectability (easy, difficult, etc).
No outside catalogs or are required.
Clear skies,
Greg
Head Dude at Skyhound
Greg
Head Dude at Skyhound