Go-astronomy logo


Caldwell 4
Caldwell 4 Iris Nebula
Credit: NASA, ESA

C4 - Iris Nebula

Caldwell 4 (NGC 7023) also known as the Iris Nebula is a diffuse nebula located within the constellation Cepheus.

C4 is best viewed during Fall, is magnitude 7*, and can be viewed with binoculars. It is 18 x 18' in size. For reference, the full moon is 30' (arc minutes) in size.

      1. Name:
      2. Iris Nebula
      1. Type:
      2. diffuse nebula
      1. NGC:
      2. 7023
      1. Magnitude:
      2. 7
      1. Viewing:
      2. binoculars
      1. Size:
      2. 18 x 18'
      1. RA:
      2. 21 01.8
      1. Dec:
      2. +68 12'
      1. Season:
      2. Fall


    * The naked eye can see up to magnitude 8 objects under ideal dark sky conditions.