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Old 19-05-2009, 03:13 PM
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Robh (Rob)
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Join Date: Feb 2009
Location: Blue Mountains, Australia
Posts: 1,338
Volunteers Needed for Naked Eye Survey

Hi all,

Do you want to know how dark your sky is?
How does the city and suburbs compare to the country?
Then join the naked-eye limiting magnitude (NELM) survey here.
It should only take about 15 minutes of your time (you will need a little time to dark adapt your eyes).

For any of the nights of the 19th through to the 25th May, could you simply note the magnitude of the faintest star you can see (naked-eye) in Crux from the attached maps. Anywhere between 7pm and midnight will be fine. Most people will only need Crux NELM 1. If you can see beyond magnitude 6 (you lucky devils!) you will need Crux NELM 2.

Then report two things back to this thread:
a) NELM
b) whether it was an inner city, an inner suburban, an outer suburban or a rural reading.


When judging NELM, make sure you can actually see the star. Not just, I thought I saw it but I can't see it now. If you can see the star but it seems to continuously fade in and out, that's fine.

The map(s) have a two-fold use ...
Once you've got the hang of it, you will be able to use the map(s) on any night you are observing to judge that night's conditions.

All data can be seen here on this thread.
The more data, the better!
Hope we get some clear skies.

Thanks in advance. Rob
Attached Files
File Type: pdf Crux NELM 1.pdf (61.3 KB, 68 views)
File Type: pdf Crux NELM 2.pdf (68.8 KB, 26 views)

Last edited by Robh; 21-05-2009 at 04:10 PM. Reason: Included mag 6.4 star to instruction 11 (Crux NELM 2)
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