Contains:  Extremely wide field
Sierra de Gredos (Spain), Sergio Díaz

Sierra de Gredos (Spain)

Sierra de Gredos (Spain), Sergio Díaz

Sierra de Gredos (Spain)

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Description

Sierra de Gredos as seen from the Mirador Estelar (stargaze viewpoint) of Navarredonda de Gredos (Ávila, Spain) in midsummer. This area has got a dark sky Starlight Foundation certification, but unfortunately the southern view is plagued by light pollution from several cities of central Spain. At the cenit, some places in the peninsula still are relatively good, but unfortunately, we have lost our horizons. See revision B for the original master image. 

Light pollution in Spain is getting worse, fast. Nation-wide transition to LED made under old and not very bright (pun intended) central and autonomous regulations in matter of energetic efficiency and light pollution, and managed directly and independently by every town, cannot end well. New regulations are underway, but their drafts scared all the astronomy community (1, 2). 

I've used this particular untracked sequence to test the background modeling script I've been developing over this last year. With the image revisions here you can have a glance of the resulting background model and the before/after images. I've included also the mask used to exclude the foreground during the background optimization (obtained by thresholding --in this particular case, it worked well because the foreground and the sky are well separated in the histogram-- and then cloning out the candle lights on the foreground). See this blog post for a few more comments on the background extraction process for this particular image. 

The final version is a composite of the sky, foreground, and me doing some selfie "postureo" as we would say here. Truth is I stumbled while climbing to the rock, heard the shutter, and immediately froze at some weird posture .

Comments

Revisions

  • Final
    Sierra de Gredos (Spain), Sergio Díaz
    Original
  • Sierra de Gredos (Spain), Sergio Díaz
    B
  • Sierra de Gredos (Spain), Sergio Díaz
    C
  • Sierra de Gredos (Spain), Sergio Díaz
    D
  • Sierra de Gredos (Spain), Sergio Díaz
    E

B

Title: Integrated Master (registered on the stars)

Description: Master resulting from the preprocessing. Stretched for visualization.

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C

Title: Mask

Description: Mask used for the background modeling process.

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D

Title: Background model

Description: Background estimation found by the optimization process.

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E

Title: Background-subtracted master

Description: Image resulting after subtracting the background model from the master image (hover for comparison).

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Histogram

Sierra de Gredos (Spain), Sergio Díaz