Hi folks,
Thought I'd reply on a few subjects now, and come back later to
catch up on the rest.
WEBCAM PROJECT:
I got a few replies to my question about using cheap cameras for
wide-field imaging, for use in making a simple "star tracking" setup
to replace encoders. Looks as if my use of a $50 Webcam was too
optimistic, but people are reporting success with low-light surveillance
cameras and video capture boards. So it appears to be possible, just
a few bucks more expensive than I'd thought.
MISCELLANEOUS PAGES:
Some people mentioned that they'd not seen the Webcam page, since it
is an "orphan" (not linked to from anywhere else on the site). For what
little it's worth, a few such pages covering miscellaneous topics
(mostly mathematical in nature) are now linked to from
http://www.projectpluto.com/miscell.htm
GN DEFINITION:
Click on a nebula that's listed in this catalog, and ask for "more
info", and click on the highlighted "GN", and you'll get the following
definition:
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The "Atlas of Galactic Nebulae" includes 1547 nebulae that appear
on the POSS or the ESO/SRC Atlas. The "Atlas of Galactic Nebulae"
shows positions, sizes, and images of all included nebulae. It
was one of the most important sources for the Nebula Databank.
Reference: Neckel, Th., Vehrenberg, H. 1985: Atlas Galaktischer
Nebel Teil I to III.
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The Nebula Databank is the work of Eric-Sven Vesting. I think the
Atlas of Galactic Nebulae may be somewhat more popular in Germany than
it is over here; I'd never heard of it before Eric mentioned it. (I
believe it's referred to as "GN" rather than "AGN" because the latter
acronym is in use for active galactic nuclei.)
"NOVA" IN CETUS:
This missing bright star is present in Hipparcos (HIP 2762), GSC
(GSC 4675 1216), and in Tycho-1 and Tycho-2.
In Tycho-1, it shows up as two separate components, 4675 1216 1
and 4675 1216 2. But Tycho-1 gives no magnitude for either star, so
Guide 7 omits them. I can't really cast much blame on the catalogs
here; it's just that I didn't have any code that said, "If a Tycho-1
star lacks magnitude data, but has an Hipparcos number, look in that
catalog and get the mag there."
This is the first (and, so far, only) such error of which I am
aware. In Guide 6, there were problems with certain stars, most
notably Xi UMa, which were present in Hipparcos but totally absent
in Tycho. With that error fixed, I thought Guide 7 was complete to
about mag 8 or so. Obviously, this was wrong.
In Tycho-2, this star shows up as a single object, 4675 1216 3,
with magnitude data given and a cross-reference to Hipparcos. So Guide
8 shows this object correctly.
This object is indeed a variable, BU Cet, varying about .1 mag in
the K (infrared) photometric band; I've no idea how much it varies
visually, but it's probably not a whole lot.
SAO DATA:
Ned, the SAO data is stored in the file
\sao\sao.lmp
in a horribly cryptic format. The only documentation for it is in the
C/C++ source code available at
http://www.projectpluto.com/sao.zip
My recommendation would be to ignore this completely, and to get the
ASCII version of the SAO from the Astronomical Data Center. They also
supply it on CD-ROM (their 'Selected Astronomical Catalogues Vol. 1'
disk), or you can get it via ftp:
ftp://adc.gsfc.nasa.gov/pub/adc/archives/catalogs/1/1131A
-- Bill