# Northern Sky Narrowband Survey - H-alpha and Continuum

- By: Tk833
- Date: 2025-10-06
- Classification: Photograph
- Museum: [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Northern_Sky_Narrowband_Survey_-_H-alpha_and_Continuum.jpg)
- Rights: [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0)
- Picture: https://invisiblenetwork.ai/thumbs/commons/thumb/a/ad/Northern_Sky_Narrowband_Survey_-_H-alpha_and_Continuum.jpg/1920px-Northern_Sky_Narrowband_Survey_-_H-alpha_and_Continuum.jpg
- Who can see it: Kids profiles and older (museums give no ratings; placed by Invisible Network from the museum's own words)

212° stereographic projection of the entire region surveyed by the Northern Sky Narrowband Survey showing hydrogen emissions and continuum light. Ionized hydrogen (Hα at 656.3 nm, without continuum) is mapped to red, blue continuum (including some \[OIII\] and Hβ emissions) is mapped to green, and red continuum (without Hα but with some \[SII\] emissions) is mapped to blue. Emission nebulae appear reddish while reflection nebulae are green to blue. Stars are partially subtracted in order to make the faint nebulae visible. The view was composed of 531,620 single exposures with a total exposure time of approximately 8,111 hours.

Emission nebulae (red) are concentrated near the galactic plane, extending from the left to the right side. Reflection nebulae (cyan), in the form of Integrated Flux Nebula, are also found at higher galactic latitudes. The cyan double ring is the ecliptic.

Other color composites of the same view

Emission lines \[OIII\], Hα, and \[SII\]

Hα in pseudo-colors

Continuum without Hα and with partially subtracted stars

True colors without subtraction of stars and emission lines