SCAT(7) SCAT(7)
NAME
scat - sky catalogue
SYNOPSIS
scat
DESCRIPTION
Scat looks up items in catalogues of objects outside the
solar system and implements database-like manipulations on
sets of such objects.
Items are read, one per line, from the standard input and
looked up in the catalogs. The result of the lookup becomes
the set of objects available to the database commands.
After each lookup or command, if more than two objects are
in the set, scat prints how many objects are in the set;
otherwise it prints the objects' descriptions or cross-index
listings (suitable for input to scat). An item is in one of
the following formats:
ngc1234
Number 1234 in the Revised New General Catalogue of
Nonstellar Objects. The output identifies the type
(eg=galaxy, pn=planetary nebula, gc=globular cluster,
oc=open cluster, dn=diffuse nebula or nc=nebular clus-
ter), possibly contained within the Large Magellanic
Cloud (in lmc) or Small Magellanic Cloud (in smc), its
position in 2000.0 coordinates and galactic coordi-
nates, and a brief description.
sao12345
Number 12345 in the Smithsonian Astrophysical Star Cat-
alogue. Output identifies the visual and photographic
magnitudes, 2000.0 coordinates, proper motion, spectral
type, multiplicity and variability class, and HD num-
ber.
m4 Catalog number 4 in Messier's catalog. The output is
the NGC number.
planetarynebula
The set of NGC objects of the specified type. The type
may be a two-letter NGC code or a full name, as above,
with no blank.
"α umi"
Star names are provided in double quotes. Known names
are the Greek letter designations, proper names such as
Betelgeuse, and bright variable stars. Greek letters
may be spelled out, e.g. alpha. Constellation names
Page 1 Plan 9 (printed 4/24/24)
SCAT(7) SCAT(7)
must be the three-letter abbreviations. The output is
the SAO number. For non-Greek names, SAO numbers and
names are listed for all stars with names for which the
given name is a prefix.
12h34m -16
Coordinates in the sky are translated to the nearest
`patch', approximately one square degree of sky. The
output is the coordinates identifying the patch, the
constellations touching the patch, and the NGC and SAO
objects in the patch. The program prints sky positions
in several formats corresponding to different preci-
sions; any output format is understood as input.
umi All the patches in the named constellation.
The commands are:
add item
Add the named item to the set.
keep class ...
Flatten the set and cull it, keeping only the specified
classes. The classes may be specific NGC types, all
stars (sao), all NGC objects (ngc), all M objects (m),
or a specified brightness range. Brightness ranges are
specified by a leading > or < followed by a magnitude.
Remember that brighter objects have lesser magnitudes.
drop class ...
Like keep, but keeps only the objects not in the speci-
fied classes.
flat Some items such as patches represents sets of items.
Flat flattens the set so scat holds all the information
available for the objects in the set.
print
Print the contents of the set. If the information
seems meagre, try flattening the set.
expand n
Flatten the set, expand the area of the sky covered by
the set to be n degrees wider, and collect all the
objects in that area. If n is zero, expand collects
all objects in the patches that cover the current set.
plot option
Expand and plot the set on the screen. The only option
is nogrid to suppress the lines of declination and
right ascension. Symbols for NGC objects are as in Sky
Atlas 2000.0.
Page 2 Plan 9 (printed 4/24/24)
SCAT(7) SCAT(7)
EXAMPLES
Plot the NGC objects and naked-eye stars in Orion.
ori
keep ngc <6
plot nogrid
Draw a map of the Pleiades.
"alcyone"
expand 1
plot
FILES
/lib/sky/*.scat
SEE ALSO
astro(7)
/lib/sky/constelnames for the three-letter abbreviations of
the constellation names.
The data was provided by the Astronomical Data Center at the
NASA Goddard Space Flight Center.
Page 3 Plan 9 (printed 4/24/24)