Re: maps for Globe at Night

[Jan Hollan <jhollan@amper....muni.cz>]

Connie, an improved set of four maps is

 http://amper.ped.muni.cz/jenik/astro/maps/GaN-Orion/45-75.pdf

including an explanatory caption replacing the maps for even poorer skies 
- for EU mid latitudes or northern US ones. I've included Sirius somehow, 
as it is the only way to find Betelgeuse and Rigel reliably under 1 mag 
limit skies, when no Orion asterism is apparent. I believe it's ready to 
be published at GaN pages -- even if OK just for our middle latitudes. 
Alternatively, those bad noisy black maps for 5 to 7 mag on GaN pages 
might be hyperlinked to my pdfs.

I was a bit angry that Petr recommended observing just an hour after 
sunset -- as it is a nonsense to investigate man-made skyglow during 
nautical twilight. But he took it from the "For Parents" page of GaN... 
One hour+ may be OK for equator, but not for mid latitudes! At 50 degrees, 
twilight (astronomical) ends 2 h after sunset these days. In London or New 
York, no change at all between 1 h and 2 h after sunset may be apparent, 
but a tremendous change continues in nature: the glory of the Heavens 
becomes revealed.

A good advice might be to observe several times, starting 1 h after sunset 
(when Evening Star with its narrow crescent is still visible in our 
latitude, through its conjunction with the Sun on Mar 27) and finishing 
when the astronomical night begins. It lasts whole two another hours at 
Polar Circle... a good way to become fully adapted to night light levels.

cheers,
 jenik