Hi Bill,

adding the line you gave a couple of mail ago solved the problem.
Thanks again for the fast help.

Does the B10 file in the Guide directory grow as you download more fields of
B1 stars or it gets overwritten each time a new field is chosen?

Regards,

Josch Hambsch

http://www.astronomie.be/hambsch
http://users.pandora.be/hambsch/

----- Original Message -----
From: "Bill J Gray" <pluto@...>
To: <guide-user@yahoogroups.com>
Sent: Monday, January 29, 2007 7:02 PM
Subject: Re: [guide-user] B1 stars


> Hi Lawrence,
>
> "Being unfamiliar with B1.0 stars or what they actually mean..."
>
> Some discussion of this is at
>
> http://www.projectpluto.com/datasets.htm#b1
>
> and I should add more, about B1.0 and other large star catalogs
> (UCAC-2, CMC-14, GSC-2.2, 2MASS, and so on).
>
> Short description: USNO-B1.0 is a star catalog with about a billion
> stars (compare to half a billion for its predecessor, USNO-A2.0, and
> about 15 million for GSC.) GSC was based on scanning in photographic
> plates of various parts of the sky. A2.0 did the same thing, except
> with pairs of plates, one red and one blue. That gives you some (very
> rough) color data, and meant that spurious objects could be dropped:
> if an "object" appeared on only one plate, it was dropped as being most
> likely a plate flaw or asteroid or something else "wrong".
>
> B1.0 did the same thing, except with _five_ sets of plates: two
> red plates, two blue plates, and an infrared plate. So for each star
> in B1.0, you may get five magnitudes. That also gave better ability to
> tell false objects from real ones.
>
> As you go up the ladder from GSC to A2.0 to B1.0, you get more
> stars, somewhat more accurate positions, and better magnitudes (though
> not by much).
>
> -- Bill
>
>
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