SH2-86 is an emission nebula in constellation Vulpecula with an apparent diameter of about 40' (arcminutes). The nebula is not very bright but contains some interesting pillar-structures and Bok globules. If is assumed that the nebula is ionized by the Vulpecula OB1 association which lies at a distance of about 6000 ly from Earth ([1]) and which contains NGC 6823, the star cluster in the center of the nebula.

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SH2-86 in [SII], H-alpha and [OIII]
This image is a false color composite where [SII] light is mapped to red, H-alpha is mapped to green and [OIII] is mapped to blue. Stars are partially subtracted using continuum images. The magenta nebula in the bottom right quarter is the reflection nebula NGC 6820.
SH2-86 in [OIII], H-alpha and [SII]
Same view as above, but [SII] and [OIII] are swapped in order to improve the visibility of the oxygen structures (reddish).
SH2-86 in H-alpha
This image shows the H-alpha light only which is visualized using pseudo colors. Faintest region are dark(red) and brightest regions are white.

Image data

FOV: 0.69° × x 0.61°
Date: 2019-2020
Location: Pulsnitz, Germany
Instrument: 400mm Newton at f=1200mm
Camera Sensor: Panasonic MN34230
Orientation: North is up (approximately)
Scale: 1 arcsec/pixel (at full resolution)
Total exposure times:
H-alpha (3nm): 8.3 h
[OIII] (3nm): 10.0 h
[SII] (3nm): 13.1 h
NIR: 0.6 h
Blue: 0.5 h

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, photon counting
  2. Dark current subtraction, flatfield correction, noise estimation
  3. Alignment and brightness calibration using stars from reference image
  4. Stacking with masking unlikely values and background correction
  5. Extracting stars from the emission line images using information from continuum images
  6. Denoising and deconvolution both components (stars and residual)
  7. RGB-composition
  8. Dynamic range compression using non-linear high-pass filter
  9. Tonal curve correction


  1. A. M. Melnik, A. K. Dambis. (2020). "Distance scale for high-luminosity stars in OB associations and in field with Gaia DR2. Spurious systematic motions". Astrophysics and Space Science. 365: 112

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