tscat.1 - plan9port - [fork] Plan 9 from user space
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tscat.1 (8927B)
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1 .TH SCAT 1
2 .SH NAME
3 scat \- sky catalogue and Digitized Sky Survey
4 .SH SYNOPSIS
5 .B scat
6 .SH DESCRIPTION
7 .I Scat
8 looks up items in catalogues of objects
9 outside the solar system
10 and implements database-like manipulations
11 on sets of such objects.
12 It also provides an interface to
13 .MR astro (1)
14 to plot the locations of solar system objects.
15 Finally, it displays images from the
16 Space Telescope Science Institute's
17 Digitized Sky Survey, keyed to the catalogues.
18 .PP
19 Items are read, one per line, from the standard input
20 and looked up in the catalogs.
21 Input is case-insensitive.
22 The result of the lookup becomes the set of objects available
23 to the database commands.
24 After each lookup or command, if more than two objects are
25 in the set,
26 .I scat
27 prints how many objects are in the set; otherwise it
28 prints the objects'
29 descriptions or cross-index listings (suitable for input to
30 .IR scat ).
31 An item is in one of the following formats:
32 .TP
33 .B ngc1234
34 Number 1234 in the New General Catalogue of
35 Nonstellar Objects, NGC2000.0.
36 The output identifies the type
37 .RB( Gx =galaxy,
38 .BR Pl =planetary
39 nebula,
40 .BR OC =open
41 cluster,
42 .BR Gb =globular
43 cluster,
44 .BR Nb =bright
45 nebula,
46 .BR C+N =cluster
47 associated with nebulosity,
48 .BR Ast =asterism,
49 .BR Kt =knot
50 or nebulous region in a galaxy,
51 .BR *** =triple
52 star,
53 .BR D* =double
54 star,
55 .BR ? =uncertain,
56 .BR - =nonexistent,
57 .BR PD =plate
58 defect, and
59 (blank)=unverified or unknown),
60 its position in 2000.0 coordinates,
61 its size in minutes of arc, a brief description, and popular names.
62 .TP
63 .B ic1234
64 Like NGC references, but from the Index Catalog.
65 .TP
66 .B sao12345
67 Number 12345 in the Smithsonian Astrophysical Star Catalogue.
68 Output identifies the visual and photographic magnitudes,
69 2000.0 coordinates, proper motion, spectral type, multiplicity and variability
70 class, and HD number.
71 .TP
72 .B m4
73 Catalog number 4 in Messier's catalog.
74 The output is the NGC number.
75 .TP
76 .B abell1701
77 Catalog number 1701 in the Abell and Zwicky
78 catalog of clusters of galaxies.
79 Output identifies the magnitude of the tenth brightest member of the cluster,
80 radius of the cluster in degrees, its distance in megaparsecs,
81 2000.0 coordinates, galactic latitude and longitude,
82 magnitude range of the cluster (the `distance group'),
83 number of members (the `richness group'), population
84 per square degree, and popular names.
85 .TP
86 .B planetarynebula
87 The set of NGC objects of the specified type.
88 The type may be a compact NGC code or a full name, as above, with no blank.
89 .TP
90 \fL"α umi"\fP
91 Names are provided in double quotes.
92 Known names are the Greek
93 letter designations, proper names such as Betelgeuse, bright variable stars,
94 and some proper names of stars, NGC objects, and Abell clusters.
95 Greek letters may be spelled out, e.g.
96 .BR alpha .
97 Constellation names must be the three-letter abbreviations.
98 The output
99 is the SAO number.
100 For non-Greek names, catalog numbers and names are listed for all objects with
101 names for which the given name is a prefix.
102 .TP
103 .B 12h34m -16
104 Coordinates in the sky are translated to the nearest `patch',
105 approximately one square degree of sky.
106 The output is the coordinates identifying the patch,
107 the constellations touching the patch, and the Abell, NGC, and SAO
108 objects in the patch.
109 The program prints sky positions in several formats corresponding
110 to different precisions; any output format is understood as input.
111 .TP
112 .B umi
113 All the patches in the named constellation.
114 .TP
115 .B mars
116 The planets are identified by their names.
117 The names
118 .B shadow
119 and
120 .B comet
121 refer to the earth's penumbra at lunar distance and the comet installed in the current
122 .MR astro (1) .
123 The output is the planet's name, right ascension and declination, azimuth and altitude, and phase
124 for the moon and sun, as shown by
125 .BR astro .
126 The positions are current at the start of
127 .IR scat 's
128 execution; see the
129 .B astro
130 command in the next section for more information.
131 .PP
132 The commands are:
133 .TF print
134 .TP
135 .BI add " item"
136 Add the named item to the set.
137 .TP
138 .BI keep " class ..."
139 Flatten the set and cull it, keeping only the specified classes.
140 The classes may be specific NGC types,
141 all stars
142 .RB ( sao ),
143 all NGC objects
144 .RB ( ngc ),
145 all M objects
146 .RB ( m ),
147 all Abell clusters
148 .RB ( abell ),
149 or a specified brightness range.
150 Brightness ranges are specified by a leading
151 .B >
152 or
153 .B <
154 followed by a magnitude.
155 Remember that brighter objects have lesser magnitudes.
156 .TP
157 .BI drop " class ..."
158 Complement to
159 .BR keep .
160 .TP
161 .BI flat
162 Some items such as patches represents sets of items.
163 .I Flat
164 flattens the set so
165 .I scat
166 holds all the information available for the objects in the set.
167 .TP
168 .BI print
169 Print the contents of the set. If the information seems meager, try
170 flattening the set.
171 .TP
172 .BI expand " n"
173 Flatten the set,
174 expand the area of the sky covered by the set to be
175 .I n
176 degrees wider, and collect all the objects in that area.
177 If
178 .I n
179 is zero,
180 .I expand
181 collects all objects in the patches that cover the current set.
182 .TP
183 .BI astro " option"
184 Run
185 .MR astro (1)
186 with the specified
187 .I options
188 (to which will be appended
189 .BR -p ),
190 to discover the positions of the planets.
191 .BR Astro 's
192 .B -d
193 and
194 .B -l
195 options can be used to set the time and place; by default, it's right now at the coordinates in
196 .BR /lib/sky/here .
197 Running
198 .B astro
199 does not change the positions of planets already in the display set,
200 so
201 .B astro
202 may be run multiple times, executing e.g.
203 .B "add mars"
204 each time, to plot a series of planetary positions.
205 .TP
206 .BI plot " option"
207 Expand and plot the set in a new window on the screen.
208 Symbols for NGC objects are as in Sky Atlas 2000.0, except that open clusters
209 are shown as stippled disks rather than circles.
210 Abell clusters are plotted as a triangle of ellipses.
211 The planets are drawn as disks of representative color with the first letter of the name
212 in the disk (lower case for inferior planets; upper case for superior);
213 the sun, moon, and earth's shadow are unlabeled disks.
214 Objects larger than a few pixels are plotted to scale; however,
215 .I scat
216 does not have the information necessary to show the correct orientation for galaxies.
217 .IP
218 The option
219 .B nogrid
220 suppresses the lines of declination and right ascension.
221 By default,
222 .I scat
223 labels NGC objects, Abell clusters, and bright stars; option
224 .B nolabel
225 suppresses these while
226 .B alllabel
227 labels stars with their SAO number as well.
228 The default size is 512×512; options
229 .B dx
230 .I n
231 and
232 .BR dy
233 .I n
234 set the
235 .I x
236 and
237 .I y
238 extent.
239 The option
240 .B zenithup
241 orients the map so it appears as it would in the sky at the time and
242 location used by the
243 .B astro
244 command
245 .RI ( q.v. ).
246 .IP
247 The output is designed to look best on an LCD display.
248 CRTs have trouble with the thin, grey lines and dim stars.
249 The option
250 .B nogrey
251 uses white instead of grey for these details, improving visibility
252 at the cost of legibility when plotting on CRTs.
253 .TP
254 .B "plate \f1[[\f2ra dec\f1] \f2rasize\f1 [\f2decsize\f1]]"
255 Display the section of the Digitized Sky Survey (plate scale
256 approximately 1.7 arcseconds per pixel) centered on the
257 given right ascension and declination or, if no position is specified, the
258 current set of objects. The maximum area that will be displayed
259 is one degree on a side. The horizontal and vertical sizes may
260 be specified in the usual notation for angles.
261 If the second size is omitted, a square region is displayed.
262 If no size is specified, the size is sufficient to display the centers
263 of all the
264 objects in the current set. If a single object is in the set, the
265 500×500 pixel block from the survey containing the center
266 of the object is displayed.
267 The survey is stored in the CD-ROM juke box; run
268 .B 9fs
269 .B juke
270 before running
271 .IR scat .
272 .TP
273 .BI gamma " value"
274 Set the gamma for converting plates to images. Default is \-1.0.
275 Negative values display white stars, positive black.
276 The images look best on displays with depth 8 or greater.
277 .I Scat
278 does not change the hardware color map, which
279 should be set externally to a grey scale; try the command
280 .B getmap gamma
281 (see
282 .IR getmap (9.1))
283 on an 8-bit color-mapped display.
284 .PD
285 .SH EXAMPLES
286 Plot the Messier objects and naked-eye stars in Orion.
287 .EX
288 ori
289 keep m <6
290 plot nogrid
291 .EE
292 .PP
293 Draw a finder chart for Uranus:
294 .EX
295 uranus
296 expand 5
297 plot
298 .EE
299 .PP
300 Show a partial lunar eclipse:
301 .EX
302 astro -d
303 2000 07 16 12 45
304 moon
305 add shadow
306 expand 2
307 plot
308 .EE
309 .PP
310 Draw a map of the Pleiades.
311 .EX
312 "alcyone"
313 expand 1
314 plot
315 .EE
316 .\" .PP
317 .\" Show a pretty galaxy.
318 .\" .EX
319 .\" ngc1300
320 .\" plate 10'
321 .\" .EE
322 .SH FILES
323 .B \*9/sky/*.scat
324 .SH SOURCE
325 .B \*9/src/cmd/scat
326 .SH SEE ALSO
327 .MR astro (1)
328 .br
329 .B \*9/sky/constelnames\ \
330 the three-letter abbreviations of the constellation names.
331 .PP
332 The data was provided by the Astronomical Data Center at the NASA Goddard
333 Space Flight Center, except for NGC2000.0, which is Copyright © 1988, Sky
334 Publishing Corporation, used (but not distributed) by permission. The Digitized Sky Survey, 102
335 CD-ROMs, is not distributed with the system.