"California Nebula" (NGC 1499)

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The 'California Nebula' (NGC 1499) is an emission nebula located in the constellation Perseus. It is a large region of excited hydrogen gas that glows in the emission line of Hydrogen-alpha. The star that is exciting the gas is believed to be ξ Persei, also called Menkib, which is the brightest star in the image shown here, lying just below the red emission nebula.

Menkib is a blue-white giant star of spectral type O7. These are apparently rather rare stars, very massive and very hot, with effective temperatures > 30,000 K. This star has an estimated distance of 433 pc (1412 light years), and a diameter believed to be ~ 10x that of our sun.

  Optics:William Optics Redcat 51 Petzval refractor 
Camera:ZWO ASI1600MM monochrome camera  
Exposure info:8+ hours total exposure / 2-frame mosaic 
Filters used:Astronomik RGB and Optolong LPRO-2 light pollution filter / Astrodon Halpha filter 
Date:January 2021 

The image above was taken through both broadband filters (Red, Green and Blue) and a narrowand H-alpha filter, with a monochrome camera and assembled into a visible light (RGB) image, and thus represents the 'true colors' of the scene. Below is a narrowband version of the image, using only the H-alpha frames to produce a black & white image. Both images are a two-frame mosaic, merged in Pixinsight.


1. Gordon, Kathryn D. et al, "Angular Sizes and Effective Temperatures of O-type Stars from Optical Interferometry with the CHARA Array." The Astrophysical Journal, Volume 869, Issue 1, article id. 37, 13 pp., 2018.