Tuesday, September 22, 2015

The Bortle Scale - Route 6 In Cortlandt NY -

The Bortle Scale - Bright suburban skies, and Route 6 In Cortlandt NY -

   Image credit: created with the free software Stellarium, retrieved from Sky & Telescope.

I'm happy to report a short, but successful "mini-field-trip" to Cortlandt New York, courtesy of my BIL, Nelson. It was the first outing for my recently acquired Binocs:

The Garrett Optical 100mm binocular telescope
-and-
The New 12x60 handhelds, from Oberwerk.

Nelson enjoyed, and remarked about the abundant FOV in the 12x60's (compared to the narrow FOV of the big Garrett's). 

Among the objects observed, were: 
M31 - The Andromeda Galaxy
M33 - The Pinwheel Galaxy
The Double Cluster in Perseus -
(NGC 869 [h Persei] and NGC 884 [Chi Persei])

And, The Milky Way looked great!

I went ahead, and set-up Google Earth, as was described on the very interesting (if somewhat eclectic Page) Here

According to this neat new map - My local skies, here at home, are:

Bortle 6   Bright suburban sky 5.1-5.5
  • the zodiacal light is invisible
  • light pollution makes the sky within 35° of the horizon glows grayish white
  • clouds anywhere in the sky appear fairly bright
  • surroundings are easily visible
  • the Milky Way is only visible near the zenith
  • M33 is not visible, M31 is modestly apparent
  • limiting magnitude with 12.5" reflector is 14.5

If this overlay technique is accurate, then my local light pollution is just about as "good" (maybe even half a magnitude better) than I had originally guesstimated. And I'm really happy about that...

If this is in fact, the case - Then I'll take it! I can work with 'Bright suburban sky'

What this all actually translates into now, for me...Is that I will (eventually) have to confirm this map's accuracy. By "manually" checking the naked-eye visibility of several different constellations / stars, etc.

According to this map, the skies (which I thought were awesome) during a recent Astro-outing, in Cortlandt New York, are:


Bortle 5   Suburban sky 5.6–6.0
  • only hints of zodiacal light are seen on the best nights in autumn and spring
  • light pollution is visible in most, if not all, directions
  • clouds are noticeably brighter than the sky
  • the Milky Way is very weak or invisible near the horizon, and looks washed out overhead
  • limiting magnitude with 12.5" reflector is 15
 Clear skies!

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