Hi folks,

A belated reply about copying B1.0 and display of Saturn and
1.4-GHz sources:

Andrea, in truth, I'd definitely be very low on the list for
a copy of B1.0. Therefore, please note that the following
discussion is of a somewhat theoretical nature.

The data comes on an 80-GByte Linux-format hard drive. One
could, in theory, put the new disk in as a second drive, next to
an existing Linux or dual-partition Windoze/Linux disk, and start
burning CD-Rs. CD-Rs can hold about 700 MBytes, a bit more than the
usual CD-ROM, so "only" about 110 disks (plus a few to allow for
dead space, etc.) would be required. If burnt in ISO format, they
could be read under either Linux or Windows.

The hard drive could then be sent back to USNO, perhaps making
the whole scheme more palatable to them.

Andrea made reference to my burning copies of GSC-ACT at cost.
That's worked out pretty well, but burning 110-disk sets would
be a bit more problematic. More likely would be making a few
such sets, then sending them out to anyone interested... with the
provision that, after copying them to their own hard drive
and/or CD-Rs, they would then mail them to the next interested
person. (Robert Burns and I have discussed a similar scheme with
the 11-disk A2.0.) Thus, one set of disks could get the data out
to several people, all basically at the cost of postage.

One of those people might have a DVD writer, and might be
talked into making a set of DVDs.

Now, before anyone gets too enthusiastic about this: the
benefits of B1.0 over A2.0 are, for 99% of us, not that much.
It's good if you're doing astrometry and are getting results to
the .3-arcsec level or so (that is, your astrometry is so good
that even the small errors in A2.0 are noticeable.) And even
most of these people will actually be better off with UCAC-2.

Pat's point about increasing storage availability is
well-taken. Ten years from now, B1.0 won't be distributed on
110 CD-Rs, or nine DVD-Rs. It will consume part of the new
multi-terabyte XYZ-Rs. (But USNO-C2.0 will have come out,
requiring several dozen XYZ-Rs.)

Albert, about the display of Saturn in Guide: its display is
wrong in one major respect: the shadow cast on the rings (and
on other objects) is computed as if Saturn were round. You can
see this most effectively if you set your "home planet" to be the
sun, then zoom in on Saturn. You'll see a bit of shadow cast on
the far side of the rings, even though as seen from the sun,
nothing ought to have shadows.

Bob, about the display of the 1.4-GHz data: problem here is
that I _thought_ this dataset was sorted in RA order. It's almost,
but not quite, sorted in that manner. Best fix right now is to
to download this file (about 650 KBytes):

http://www.gwi.net/~pluto/north20.zip

and unZIP it in your Guide directory. It is really the same
data file as the original, except properly sorted in RA.

-- Bill