Hemisphere:  Northern  ·  Contains:  46 ksi Per  ·  California nebula  ·  IC2005  ·  IC2027  ·  Menkib  ·  NGC 1499  ·  NGC1499  ·  Sh2-220  ·  The star ξPer
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California nebula Ced26/LBN756/NGC1499/PGC3517586/Sh2-220 (c-sho), 


            Ram Samudrala
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California nebula Ced26/LBN756/NGC1499/PGC3517586/Sh2-220 (c-sho)

Imaging telescopes or lenses: Takahashi FC-100DF

Imaging cameras: QHY163M

Mounts: Software Bisque Paramount MyT

Focal reducers: Takahashi Reducer FC-35

Software: SharpCap Pro  ·  PixInsight  ·  Software Bisque TheSkyX Professional Suite

Filters: Astrodon OIII 1.25 3nm  ·  Astrodon Ha 1.25 5nm  ·  Astrodon SII 31mm 3nm

Dates:Sept. 27, 2017Sept. 25, 2019Sept. 26, 2019

Astrodon Ha 1.25 5nm: 49x420" (gain: 100.00) -15C bin 1x1
Astrodon OIII 1.25 3nm: 30x420" (gain: 200.00) -15C bin 1x1
Astrodon SII 31mm 3nm: 31x420" (gain: 200.00) -15C bin 1x1

Integration: 12.8 hours

Darks: ~40

Avg. Moon age: 19.83 days

Avg. Moon phase: 22.37%

Bortle Dark-Sky Scale: 3.00

Mean FWHM: 3.00

Temperature: 15.00

Astrometry.net job: 2950567

RA center: 4h 1' 6"

DEC center: +36° 11' 33"

Pixel scale: 2.318 arcsec/pixel

Orientation: 1.199 degrees

Field radius: 1.866 degrees

Resolution: 4631x3482

Locations: Ram Samudrala, Youngstown, NY, United States

Data source: Backyard


The nebula, so named due to its shape resembling the current borders of the state of California, lies at about a distance of ~1300 light years from Earth located in the constellation Perseus. Coincidentally, it transits with its zenith in central California, since the latitude matches its declination. Its width is just a bit under that of the diametre of the moon when viewed from Earth (~ half a degree), but its length however is 2.4 degrees, roughly five times that of the moon's apparent diametre.

The bright star close to the centre is Xi Persei aka Menkib which is primarily responsible for exciting the gases in the nebula and its resulting fluorescence, apparently due to ionising hydrogen beta radiation (which isn't one of the emission lines being measured by my filters, cf. the Balmer series).

The image as you see it consists mostly of Ha and S2 data. There is some O3 signal that is very faint but I did manage to pull it out. These images are minimally processed. I spent some time doing sophisticated processing but it went nowhere, whereas this is a simple linear combination of the three filters' light frames, followed by stretching and colour manipulation of the combined image in PixInsight to roughly match its namesake's colours (again, no Photoshop CC this time), and that's it!

Lurking in the background of the image are galaxies IC2005 and IC2027, which are magnitude 16 galaxies. The latter is visible at the top left if you look very closely. The former is in the top left quadrant, apparently behind the nebula.

As always, thanks for looking!



Ram Samudrala
License: Attribution Creative Commons


  • Final
    California nebula Ced26/LBN756/NGC1499/PGC3517586/Sh2-220 (c-sho), 


            Ram Samudrala
  • California nebula Ced26/LBN756/NGC1499/PGC3517586/Sh2-220 (c-sho), 


            Ram Samudrala
  • California nebula Ced26/LBN756/NGC1499/PGC3517586/Sh2-220 (c-sho), 


            Ram Samudrala


Description: Ha data only.


Description: Alternate version with more yellow instead of golden tones.

Sky plot

Sky plot


California nebula Ced26/LBN756/NGC1499/PGC3517586/Sh2-220 (c-sho), 


            Ram Samudrala