Monday, November 28, 2011

Light pollution

Here is the light pollution map for my site (in the green zone):

ColorArtificial / Natural
Sky Brightness
Sky Brightness
mags / sq arcsec
V Band
Bortle Scale
Description (Descriptions are approximate. Your sky may vary.)

< 0.0122.00 to 21.991 Gegenschein visible. Zodiacal light annoyingly bright. Rising milkyway confuses some into thinking it's dawn. Limiting magnitude 7.6 to 8.0 for people with exceptional vision. Users of large dobsonian telescopes are very happy.

0.01 to 0.1121.99 to 21.892 Faint shadows cast by milkyway visible on white objects. Clouds are black holes in the sky. No light domes. The milky way has faint extentions making it 50 degrees thick. Limiting magntiude 7.1 to 7.5.

0.11 to 0.3321.89 to 21.693 Low light domes (10 to 15 degrees) on horizon. M33 easy with averted vision. M15 is naked eye. Milky way shows bulge into Ophiuchus. Limiting magnitude 6.6 to 7.0.

0.33 to 1.021.69 to 21.254 Zodiacal light seen on best nights. Milkyway shows much dark lane structure with beginnings of faint bulge into Ophiuchus. M33 difficult even when above 50 degrees. Limiting magnitude about 6.2 to 6.5.

1.0 to 3.021.25 to 20.494.5 Some dark lanes in milkyway but no bulge into Ophiuchus. Washed out milkyway visible near horizon. Zodiacal light very rare. Light domes up to 45 degrees. Limiting magnitude about 5.9 to 6.2.

3.0 to 9.020.49 to 19.505 Milkyway washed out at zenith and invisible at horizon. Many light domes. Clouds are brighter than sky. M31 easily visible. Limiting magnitude about 5.6 to 5.9.

9.0 to 27.019.50 to 18.386 or 7 Milkyway at best very faint at zenith. M31 difficult and indestinct. Sky is grey up to 35 degrees. Limiting magntidue 5.0 to 5.5.

>27.0<18.388 or 9 Entire sky is grayish or brighter. Familliar constellations are missing stars. Fainter constellations are absent. Less than 20 stars visible over 30 degrees elevation in brigher areas. Limiting magntude from 3 to 4. Most people don't look up. CCD imaging is still possible. But telescopic visual observation is usually limited to the moon, planets, double stars and variable stars.

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