Xi UMa added to 6 mag and 7 mag Leo maps

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

Dear Connie and Mark,

today I've been informed that Xi UMa was missing from Leo maps reaching to 
6 mag and 7 mag -- obviously some problem with the Hipparcos catalogue.

Really, this is the brightest star with missing accurate coordinates there 
(due to being a quickly moving binary star -- and the first one discovered 
binary, by the very Herschel senior). My new colleague Karel tried to make 
his own detailed maps and found a problem with the star, then checked my 
maps and saw it misses there.

The star, Alula Australis, is the southermost claw of the Big Bear. It is 
important, as this leg, similarly as the two other more conspicuous ones 
in the sky, has to be formed by two stars, not just one...

I've corrected all Leo maps and the corresponding zips and tarballs; thaks 
to this, Leo graymaps are for ZE=0.25 mag as the other ones now, not 0.20 
mag as erroneously before.

As I tried to use screen maps myself (with the monitor set to minimum 
light possible, still 100x brigher than our city sky), the only usable 
mode was using a image viewer in a fullscreen mode. This way the maps with 
varying limits can be changed easily, without any disturbing white 
borders.

To ease such a way of comparing the sky and the screen, I've included a 
series of zip files for all latitudes, with the bitmaps in separate 
directories (a subset of the whole tree with the maps), see the master 
directory
           http://amper.ped.muni.cz/GaN2011/


Of course, my offer to produce graymaps with lower pixel numbers holds. 
Just, what xnumber times ynumber they should be?


In Brno, the sky was never ZE=0.25 mag. Most of the time it was over 0.40 
mag (as I measured sunset with a luxmeter), but at the end it even better 
than 0.20 mag (the darkest night ever in my 5+years measurements).
I am inclined to prepare sets for more ZEs than just one. For stars below 
40 degrees, it seems to be a must.

keep looking up,
 Jenik