NGC 7023 (Cepheus)
Fig. 1 - Clogged with cosmic dust: The reflection nebula NGC 7023 in the constellation Cepheus, photographed with an 8-inch f/4 Newtonian reflector on a ZWO AM5 mount.
| Object name: | Constellation: | Coordinates: | Apparent size: | Visual brightness: |
|---|---|---|---|---|
| NGC 7023 (= Caldwell 4) | Cepheus | 21h02m / +68°10' | 18' x 18' | 6.8 mag |
The bright reflection nebula NGC 7023 (Iris Nebula, Caldwell 4, LBN 487) in the constellation Cepheus. The Iris Nebula is glugged with cosmic dust, scattering the light of magnitude 7.4 star HD 200775 (= SAO 19158). The name of the nebula comes from the fact that, in color photographs, it resembles a blue blooming iris flower. NGC 7023 measures six light-years in diameter and is about 1,300 light-years from Earth.
NGC 7023 was discovered by German-born British astronomer and composer William Herschel in 1794 (source: Wikipedia).
Exposure time: 4h 30min (90x3min) at gain 100 and -10°C, taken on September 20/21, 2025. Processing with Astro Pixel Processor (APP) and Photoshop. Darks, flats, and bias were used.
Equipment: Cooled ASI 2600MC Pro camera, TeleVue Paracorr Type II coma corrector, 8" f/4 "ONTC" Newtonian telescope riding on a ZWO AM5 Strain Wave Mount, ZWO OAG-L off axis system, ASI 174MM Mini guide camera, ASIAIR Plus.
NGC 7023 was also captured with a 16-inch dobsonian on an equatorial platform, using a DSLR camera. The image can be seen here.
Fig. 2 - Search chart for NGC 7023. Copyright 2025 'The Mag-7 Star Atlas Project', www.siaris.net.