scat 8.7 KB

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  1. .TH SCAT 7
  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. .IR astro (7)
  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. .IR astro (7).
  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. .I 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. .IR astro (7)
  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 /lib/sky/*.scat
  324. .SH SOURCE
  325. .B /sys/src/cmd/scat
  326. .SH SEE ALSO
  327. .IR astro (7)
  328. .br
  329. .B /lib/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.