HII region around California Nebula (NGC 1499)

Around the California Nebula (NGC 1499) there is a huge HII region which lies behind the dust in constellations Perseus and Taurus and thus is only visible in the voids and less dense regions of these molecular clouds. That nebula was already partially depicted in the view of the Milky Way from Taurus to Perseus. The 30°×30° wide-field view of this page (probably) shows entire nebula.

Full views

Click on the images to load a full resolution version with more than 100 megapixels using a JavaScript viewer.

HII region around California Nebula (NGC 1499)
This image is a false color composite in which H-alpha (including red continuum) is mapped to red, blue continuum (including [OIII] and H-beta emissions) is mapped to green, and red continuum (without H-alpha) is mapped to blue. Reflection nebulae appear green to blue, while HII regions are red. Stars in the continuum channels are partially subtracted to make the faint nebulae visible.
The greenish star cluster at the bottom are the Pleiades (M45, greenish here because blue continuum is mapped to green). Distance is about 130pc (430 light-years). The dust which scatters the light from the stars lies about 0.3pc to 0.7pc (1 to 2 light-years) in front of the stars, see [1]. The other reflection nebulae (greenish to blue) belong to different Molecular Clouds in constellations Taurus, Perseus and Aries. Within the voids of these molecular clouds emission nebulae (red) are visible which have a similar structure, i.e. these nebulae seem to to belong to a larger structure which is described below.


The view above show some nebulae that cannot be found in catalogs. (The JavaScript Viewer allows identifying objects using catalogs or SIMBAD and defining new objects.) Some (probably not all) of these unexplored nebulae have been collected in the list below. Click on the following links for a presentation. Notes

Image data

Images where captured with a camera array which is described on the instruments page.

Image data are:

Projection type: Stereographic
Center position: RA: 3h48', DEC: 35°
Orientation: North is up
Scale: 10 arcsec/pixel (in center at maximum resolution)
FOV: 30°×30° (through center)
Exposure times: Sum of exposure times of all frames used to calculate the image.
H-alpha: 11.1 d
Continuum channels: 5.8 d

Image processing

All image processing steps are deterministic, i.e. there was no manual retouching or any other kind of non-reproducible adjustment. The software which was used can be downloaded here.

Image processing steps where:

  1. Bias correction, dark current subtraction, flatfield correction
  2. Alignment and brightness calibration using stars from reference image
  3. Stacking with masking unlikely values and background correction
  4. Star subtraction
  5. Denoising and deconvolution both components (stars and residual)
  6. RGB-composition (same factor for stars and residual for the true color composite)
  7. Dynamic range compression using non-linear high-pass filter
  8. Tonal curve correction


  1. Gibson, S.J.; Nordsieck, K.H. (2003). "The Pleiades Reflection Nebula. II. Simple Model Constraints on Dust Properties and Scattering Geometry". The Astrophysical Journal. 589 (1): 362–377.
  2. P. A. B. Galli 1, L. Loinard 2,3 H. Bouy 1, L. M. Sarro 4, G. N. Ortiz-León 5, S. A. Dzib 5, J. Olivares 1, M. Heyer 6, J. Hernandez 7, C. Román-Zúñiga 7, M. Kounkel 8, and K. Covey, (2019). "Structure and kinematics of the Taurus star-forming region from Gaia-DR2 and VLBI astrometry". Astronomy & Astrophysics 630: A137.
  3. Gisela N. Ortiz-León et al. (2018.) "The Gould's Belt Distances Survey (GOBELINS). V. Distances and Kinematics of the Perseus Molecular Cloud." The Astrophysical Journal, 865 (1): 73
  4. Ungerechts, H. & Thaddeus, P. (1987). "A CO survey of the dark nebulae in Perseus, Taurus, and Auriga". Astrophysical Journal Supplement Series, 63: 645-660.

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