Visibility Index

Visibility Index is a short coded description of the appearance of the object. How easy it is too see, and is there any details visible with unaided eye?

There are three groups on codes:

1234 npsm fc

  • visibility class:
    • 1 easy
    • 2 moderate
    • 3 difficult, possible with average eyesight in good conditions
    • 4 very difficult, possible with good eyesight in good conditions, or suspect visibility
  • appearance:
    • n nebulous or glow
    • p starlike (with nebulae)
    • s one star
    • m multiple stars
  • details, shape, color:
    • f recognizable shape or details, "features"
    • c color visible
    • none no shape or details


  • 1 m f = easy, multiple stars, details or shape
  • 2 nm f = moderate easy, nebulous with multiple stars, details or shape