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Plan 9 - man page for scat (plan9 section 7)

SCAT(7) 			 Miscellaneous Information Manual			  SCAT(7)

NAME
       scat - sky catalogue and Digitized Sky Survey

SYNOPSIS
       scat

DESCRIPTION
       Scat looks up items in catalogues of objects outside the solar system and implements data-
       base-like manipulations on sets of such objects.  It also displays images from  the  Space
       Telescope Science Institute's Digitized Sky Survey, keyed to the catalogues.

       Items  are  read,  one  per  line,  from the standard input and looked up in the catalogs.
       Input is case-insensitive.  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 New General Catalogue of  Nonstellar  Objects,  NGC2000.0.   The
	      output  identifies the type Pl=planetary nebula, OC=open cluster, Gb=globular clus-
	      ter,  Nb=bright  nebula,	C+N=cluster  associated  with  nebulosity,  Ast=asterism,
	      Kt=knot  or  nebulous region in a galaxy, ***=triple star, D*=double star, ?=uncer-
	      tain, -=nonexistent, PD=plate defect, and (blank)=unverified or unknown), its posi-
	      tion  in	2000.0	coordinates, its size in minutes of arc, a brief description, and
	      popular names.

       ic1234 Like NGC references, but from the Index Catalog.

       sao12345
	      Number 12345 in the Smithsonian Astrophysical Star  Catalogue.   Output  identifies
	      the visual and photographic magnitudes, 2000.0 coordinates, proper motion, spectral
	      type, multiplicity and variability class, and HD number.

       m4     Catalog number 4 in Messier's catalog.  The output is the NGC number.

       abell1701
	      Catalog number 1701 in the Abell and Zwicky catalog of clusters of galaxies.   Out-
	      put  identifies  the magnitude of the tenth brightest member of the cluster, radius
	      of the cluster in degrees, its distance in megaparsecs, 2000.0 coordinates,  galac-
	      tic  latitude and longitude, magnitude range of the cluster (the `distance group'),
	      number of members (the `richness group'), population per square degree, and popular
	      names.

       planetarynebula
	      The  set	of NGC objects of the specified type.  The type may be a compact NGC code
	      or a full name, as above, with no blank.

       "a umi"
	      Names are provided in double quotes.  Known names are  the  Greek  letter  designa-
	      tions,  proper  names  such  as  Betelgeuse, bright variable stars, and some proper
	      names of stars, NGC objects, and Abell clusters.	Greek letters may be spelled out,
	      e.g.  alpha.  Constellation names must be the three-letter abbreviations.  The out-
	      put is the SAO number.  For non-Greek names, catalog numbers and names  are  listed
	      for all objects 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  Abell, NGC, and SAO objects in the
	      patch.  The program prints sky positions in several formats corresponding  to  dif-
	      ferent precisions; 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),
	      all Abell clusters (abell), 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 ...
	      Complement to keep.

       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 meager, 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.  Abell clusters are plotted as a triangle of ellipses.

       plate [[ra dec] rasize [decsize]]
	      Display the section of the Digitized Sky Survey (plate scale approximately 1.7 arc-
	      seconds per pixel) centered on the given right ascension and declination or, if  no
	      position	is  specified, the current set of objects.  The maximum area that will be
	      displayed is one degree on a side.  The horizontal and vertical sizes may be speci-
	      fied  in	the  usual  notation for angles.  If the second size is omitted, a square
	      region is displayed.  If no size is specified, the size is  sufficient  to  display
	      the  centers  of	all the objects in the current set.  If a single object is in the
	      set, the 500x500 pixel block from the survey containing the center of the object is
	      displayed.   The	survey is stored in the CD-ROM juke box; run 9fs juke before run-
	      ning scat.

       gamma value
	      Set the gamma for converting plates to bitmaps.  Default is -1.0.  Negative  values
	      display  white stars, positive black.  The images look best on displays with ldepth
	      3.  Scat does not change the hardware color map, which should be set externally  to
	      a grey scale; try the command fb/getmap gamma (see getmap(9.1)).

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

       Show a pretty galaxy.
	    ngc1300
	    plate 10'

FILES
       /lib/sky/*.scat

SOURCE
       /sys/src/cmd/scat

SEE ALSO
       astro(7)
       /lib/sky/constelnames   the three-letter abbreviations of the constellation names.

       The  data  was  provided  by the Astronomical Data Center at the NASA Goddard Space Flight
       Center, except for NGC2000.0, which is Copyright (C)  1988,  Sky  Publishing  Corporation,
       used  by  permission.   The Digitized Sky Survey, 102 CD-ROMs, is not distributed with the
       system.

											  SCAT(7)


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