Date: Thu, 3 Dec 92 05:07:34 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #491 To: Space Digest Readers Precedence: bulk Space Digest Thu, 3 Dec 92 Volume 15 : Issue 491 Today's Topics: Space FAQ 03/15 - Data Sources Space FAQ 04/15 - Calculations Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: 2 Dec 92 17:43:06 GMT From: Jon Leech Subject: Space FAQ 03/15 - Data Sources Newsgroups: sci.astro,sci.space,news.answers Archive-name: space/data Last-modified: $Date: 92/12/02 12:34:36 $ ONLINE AND OTHER SOURCES OF IMAGES, DATA, ETC. INTRODUCTION A wide variety of images, data, catalogs, information releases, and other material dealing with space and astronomy may be found on the net. A few sites offer direct dialup access or remote login access, while the remainder support some form of file transfer. Many sites are listed as providing 'anonymous FTP'. This refers to the File Transfer Protocol on the Internet. Sites not connected to the Internet cannot use FTP directly, but there are a few automated FTP servers which operates via email. Send mail containing only the word HELP to ftpmail@decwrl.dec.com or bitftp@pucc.princeton.edu, and the servers will send you instructions on how to make requests. The sources with the broadest selection of material are the NASA Ames SPACE archive and the National Space Science Data Center. Don't even ask for images to be posted to the net. The data volume is huge and nobody wants to spend the time on it. VIEWING IMAGES The possible combinations of image formats and machines is forebodingly large, and I won't attempt to cover common formats (GIF, etc.) here. To read PDS and VICAR (and many other) formats on Unix systems running X, use XV 2.11, available by anonymous FTP from export.lcs.mit.edu (18.24.0.12) in contrib/xv-2.11.tar.Z and the other standard X11 FTP sites. The FAQ for the Usenet group alt.binaries.pictures discusses image formats and how to get image viewing software. A copy of this document is available by anonymous FTP from the Usenet FAQ archives at pit-manager.mit.edu (18.72.1.58), in directory pub/usenet/alt.binaries.pictures. ONLINE ARCHIVES NASA AMES Extensive archives are maintained at NASA Ames and are available via anonymous FTP or an email server. These archives include many images and a wide variety of documents including this FAQ list, NASA press releases, shuttle launch advisories, and mission status reports. Please note that these are NOT maintained on an official basis. FTP users should connect to ames.arc.nasa.gov (128.102.18.3) and look in pub/SPACE. pub/SPACE/Index contains a listing of files available in the archive (the index is about 200K by itself). To access the archives by email, send a letter to archive-server@ames.arc.nasa.gov (or ames!archive-server). In the subject of your letter (or in the body), use commands like: send SPACE Index send SPACE SHUTTLE/ss01.23.91. The capitalization of the subdirectory names is important. All are in caps. Only text files are handled by the email server at present; use one of the FTP email servers described in the introduction to this section for images or programs. The Magellan Venus and Voyager Jupiter, Saturn, and Uranus CD-ROM image disks have been put online in the CDROM and CDROM2 directories. The disks will be rotated on a weekly basis. Thousands of images are available in these collections. The GIF directory contains images in GIF format. The VICAR directory contains Magellan images in VICAR format (these are also available in the GIF directory). A PC program capable of displaying these files is found in the IMDISP directory (see the item "VIEWING IMAGES" below). The NASA media guide describes the various NASA centers and how to contact their public affairs officers; this may be useful when pursuing specific information. It's in MISC/media.guide. Any problems with the archive server should be reported to Peter Yee (yee@ames.arc.nasa.gov). NASA SPACELINK SpaceLink is an online service located at Marshall Space Flight Center in Huntsville, Alabama. The system is specifically designed for teachers. The data base is arranged to provide easy access to current and historical information on NASA aeronautics, space research, and technology transfer information. Also included are suggested classroom activities that incorporate information on NASA projects to teach a number of scientific principles. Unlike bulletin board systems, NASA Spacelink does not provide for interaction between callers. However it does allow teachers and other callers to leave questions and comments for NASA which may be answered by regular mail. Messages are answered electronically, even to acknowledge requests which will be fulfilled by mail. Messages are generally handled the next working day except during missions when turnaround times increase. The mail system is closed- loop between the user and NASA. SpaceLink also offers downloadable shareware and public domain programs useful for science educators as well as space graphics and GIF images from NASA's planetary probes and the Hubble Telescope. You can dial in at (205)-895-0028 (300/1200/2400/9600(V.32) baud, 8 bits, no parity, 1 stop bit), or telnet to spacelink.msfc.nasa.gov (128.158.13.250, also known as xsl.msfc.nasa.gov) if you're on the Internet. Anonymous FTP capability will be offered in the future. Most of this information is also available from the Ames server in directory SPACELINK. NATIONAL SPACE SCIENCE DATA CENTER (NSSDC) The National Space Science Data Center is the official clearinghouse for NASA data. The data catalog (*not* the data itself) is available online. Internet users can telnet to nssdca.gsfc.nasa.gov (128.183.36.23) and log in as 'NODIS' (no password). You can also get the catalog by sending email to 'request@nssdc.gsfc.nasa.gov'. You can also dial in at (301)-286-9000 (300, 1200, or 2400 baud, 8 bits, no parity, one stop). At the "Enter Number:" prompt, enter MD and carriage return. When the system responds "Call Complete," enter a few more carriage returns to get the "Username:" and log in as 'NODIS' (no password). The system is menu-driven; topics available as of 4/10/92 are: 1 - Master Directory - NASA & Global Change 2 - Personnel Information Management System 3 - Nimbus-7 GRID TOMS Data 4 - Interplanetary Medium Data (OMNI) 5 - Request data and/or information from NSSDC 6 - Geophysical Models 7 - CANOPUS Newsletter 8 - International Ultraviolet Explorer Data Request 9 - CZCS Browse and Order Utility 10 - Astronomical Data Center (ADC) 11 - STEP Bulletin Board Service 12 - Standards and Technology Information System Data can be ordered from the NSSDC on CD-ROM and other formats. Among the many types of data available are Voyager, Magellan, and other planetary images, Earth observation data, and star catalogs. Viewers for Macintosh and IBM systems are also available. As an example of the cost, an 8 CD set of Voyager images is $75. Data may ordered online, by email, or by physical mail. The postal address is: National Space Science Data Center Request Coordination Office Goddard Space Flight Center Code 633 Greenbelt, MD 20771 Telephone: (301) 286-6695 Email address: request@nssdca.gsfc.nasa.gov NSSDCA is also an anonymous FTP site, but no comprehensive list of what's there is available at present. SPACE AND PLANETARY IMAGE FACILITY Available 24 hours a day via anonymous FTP from pioneer.unm.edu. Has approximately 150 CD-ROM's full of imagery, raw, and tabular data. To start, get the file: pioneer.unm.edu:pub/info/beginner-info This will hopefully give you all of the information you need to get data from their machine. beginner-info has been translated to other languages, you should look inside pub/info for the particular language that meets your needs. Contact help@pioneer.unm.edu. SPACE TELESCOPE SCIENCE INSTITUTE ELECTRONIC INFORMATION SERVICE stsci.edu (130.167.1.2) has a large amount of information about the Hubble Space Telescope available by anonymous FTP, such as status reports and newsletters, in addition to material oriented towards HST observers and proposers. Get the top level README file to begin with. Contact Pete Reppert (reppert@stsci.edu) or Chris O'Dea (odea@stsci.edu). ASTRONOMICAL DATABASES The full SAO stellar database is *NOT* available online, probably due to the 40 MB size. It may be ordered on magnetic tape from the NSSDC. A subset containing position and magnitude only is available by FTP (see "Astronomy Programs" below). nic.funet.fi (128.214.6.100) has a large collection of astronomical programs for many types of computers, databases of stars and deep sky objects, and general astronomy information in directory /pub/astro. This site is mainly for European users, but overseas connections are possible. mandarin.mit.edu (18.82.0.21) has the following data available via anonymous FTP in directory /astro: StarChart v3.2, orbital elements for bright comets and asteroids, the Yale Bright Star catalog, Saguaro Astronomy Club Deepsky and Double Star databases, some PC astronomy programs, and possibly more. Get astro/README. Contact ccount@athena.mit.edu with questions. The Ames archives contain a database of 8,436 galaxies including name, RA, declination, magnitude, and radial velocity in MISC/galaxy.dat. Supplied by Wayne Hayes (wayne@csri.utoronto.ca). iris1.ucis.dal.ca (129.173.18.107) has a number of GIFs from Voyager, Hubble, and other sources available by anonymous FTP in pub/gif (most of this data is also in SPACE/GIF on the Ames server). Please restrict access to 5pm - 8am Atlantic time. pomona.claremont.edu has the Yale Bright Star catalog for anonymous FTP in directory [.YALE_BSC]. Contact James Dishaw (jdishaw@hmcvax.claremont.edu). The Hubble Guide Star catalog is available on CD-ROM for the Mac and PC for $49.95 US (catalog # ST101). Astronomical Society of the Pacific 390 Ashton Ave. San Francisco, CA 94112 Phone: (415) 337-2624 9 AM - 3 PM Pacific Time FAX: (415) 337-5205 For German (and possibly other European) readers, Jost Jahn has a service to distribute astronomical data to interested amateurs at cost. About 30-40 catalogs are available for DM 6..8/disk. Several floppy disk formats are available. Because of the expense of receiving email on his system, he asks that you contact him by physical mail: Jost Jahn Neustaedter Strasse 11 W-3123 Bodenteich GERMANY Phone: FRG-5824-3197 ASTRONOMY PROGRAMS Various astronomy-related programs and databases posted to the net in the past are archived for anonymous FTP at multiple sites, including ftp.uu.net (137.39.1.9). Also see the ASTRO-FTP list posted to sci.astro monthly, which is more complete than this list. Astonomical/Space-related sources of interest in comp.sources.unix: Volume 8: phoon moon phase and date routines Volume 12,13: starchart starchart program & Yale Star data Volume 15: moontool shows moon phase picture on Suns Volume 16: sao reduced SAO catalog Astonomical/Space-related sources of interest in comp.sources.misc: Volume 8: moon another moon phase program Volume 11: starchart starchart program, version 3.2 Volume 11: n3emo-orbit orbit: track earth satellites Volume 12: starchart2 starchart program, update to version 3.2.1 Volume 13: jupmoons plotter for Jupiter's major moons [in perl] Volume 13: lunisolar lunisolar (not sure what this does) Volume 14: ephem-4.21 astronomical ephemeris, v4.21 Volume 14: n3emo-orbit patch to orbit 3.7 Volume 18: planet planet generation simulator Elwood Downey (e_downey@tasha.cca.cr.rockwell.com), the author of "ephem", has offered to mail copies to people who can't find it on one of the archives. XSAT, an X Window System based satellite tracking program, is available by anonymous FTP from export.lcs.mit.edu (18.24.0.12) in contrib/xsat1.0.tar.Z. Contact Dave Curry (davy@ecn.purdue.edu) for more information. Xsky, a computerized sky atlas for the X Window System, is available for anonymous FTP on arizona.edu in the directory [.SOFTWARE.UNIX.XSKY] as xsky.tarz. Contact Terry R. Friedrichsen (terry@venus.sunquest.com) for more information. The "Variable Stars Analysis Software Archive" is available via anonymous FTP from kauri.vuw.ac.nz (130.195.11.3) in directory pub/astrophys. This is intended for specialists in this field, and they would appreciate people from outside New Zealand confining their FTP access to the astrophys directory, as they pay a significant amount for Internet access. Contents are relatively sparse at present due to the youth of the archive - contributions are encouraged. Contact the archive administrator, Timothy Banks (bankst@kauri.vuw.ac.nz) for more information. The "IDL Astronomy Users Library" is available by anonymous FTP from idlastro.gsfc.nasa.gov (128.183.57.82). This is a central repository for general purpose astronomy procedures written in IDL, a commercial image processing, plotting, and programming language. Contact Wayne Landsman (landsman@stars.gsfc.nasa.gov) for more information. ORBITAL ELEMENT SETS The most recent orbital elements from the NASA Prediction Bulletins are carried on the Celestial BBS, (513)-427-0674. Documentation and tracking software are also available on this system. The Celestial BBS may be accessed 24 hours/day at 300, 1200, or 2400 baud using 8 data bits, 1 stop bit, no parity. Orbital element sets are available via anonymous FTP from the following sites: archive.afit.af.mil (129.92.1.66) NASA,TVRO,Shuttle directory: /pub/space ftp.funet.fi (128.214.6.100) NASA,TVRO,Molczan,CelBBS, directory: /pub/astro/pc/satel Shuttle (*) kilroy.jpl.nasa.gov (128.149.1.165) NASA,Molczan directory: /pub/space/ SPACE DIGEST ARCHIVES Copies of back issues of Space Digest are archived on LISTSERV@UGA.BITNET. Send mail containing the message "INDEX SPACE" to get an index of files; send it the message "GET filename filetype" to get a particular file. LANDSAT AND NASA PHOTOS You can get black-and-white 1:1M prints, negatives, or positives for $10, $18, $12 respectively for any Landsat data more than 2 years old from EDC, (Eros (Earth Resources Orbiting Satellite) Data Center). Call them at (605)-594-6511. You get 80 meter resolution from the MSS scanner, 135x180 kilometers on a picture 135x180 mm in size. I think you have to select one band from (green, red, near IR, second near IR), but I'm not sure. Digitial data is also available at higher prices. Transparencies of all NASA photos available to the public can be borrowed from the NASA photo archive; you can have copies or prints made. NASA Audio-Visual Facility 918 North Rengstorff Ave Mountain View, CA 94043 (415)-604-6270 PLANETARY MAPS The USGS address for maps of the planets is: U.S. Geological Survey, Distribution Branch, Box 25286, Federal Center, Bldg. 41 Denver, CO 80225 Maps cost $2.40 to $3.10 per sheet (a few come in sets of 2 or 3 sheets). The best global maps of Mars based on Viking images are 1:15,000,000 scale in 3 sheets. These maps are: I-1535 (2 sheets only) - relief, albedo, names I-1535 I-1618 (3 sheets) - relief, names I-2030 (3 sheets) - relief, topographic contours I-1802-A,B,C (3 sheets) - geology There are many other maps as well: 30 sheets at 1:5,000,000 scale in relief, albedo, geology, photomosaic forms (not all 30 sheets available in all formats); 140 sheets at 1:2,000,000 scale as photomosaics of the whole planet, about 100 sheets of interesting sites at 1:500,000 scale in photomosaic format, and lots of special sheets. Then there are maps of Mercury, Venus, the Moon, the four Galilean Satellites, six moons of Saturn and five of Uranus. [Phil Stooke (stooke@vaxr.sscl.uwo.ca), the author of this item, has offered to respond to email requests for information on any topic relating to lunar and planetary maps.] COMETARY ORBIT DATA The Central Bureau for Astronomical Telegrams and the Minor Planet Center announce the sixth edition of the Catalogue of Cometary Orbits in IAU Circular 4935. The catalogue contains 1292 entries which represent all known comets through November 1989 and is 96 pages long. Non-subscribers to the Circulars may purchase the catalogue for $15.00 while the cost to subscribers is $7.50. The basic catalogue in ASCII along with a program to extract specific orbits and calculate ephemerides is available on MS-DOS 5.25-inch 2S2D diskette at a cost of $75.00 (the program requires an 8087 math coprocessor). The catalogue alone is also available by e-mail for $37.50 or on magnetic tape for $300.00. Except for the printed version of the catalogue, the various magnetic media or e-mail forms of the catalogue do not specifically meantion non-subscribers. It is possible that these forms of the catalogue may not be available to non-subscribers or that their prices may be more expensive than those given. Mail requests for specific information and orders to: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory Cambridge, MA 02138, USA NEXT: FAQ #4/15 - Performing calculations and interpreting data formats ------------------------------ Date: 2 Dec 92 17:43:15 GMT From: Jon Leech Subject: Space FAQ 04/15 - Calculations Newsgroups: sci.astro,sci.space,news.answers Archive-name: space/math Last-modified: $Date: 92/12/02 12:34:43 $ PERFORMING CALCULATIONS AND INTERPRETING DATA FORMATS COMPUTING SPACECRAFT ORBITS AND TRAJECTORIES References that have been frequently recommended on the net are: "Fundamentals of Astrodynamics" Roger Bate, Donald Mueller, Jerry White 1971, Dover Press, 455pp $8.95 (US) (paperback). ISBN 0-486-60061-0 NASA Spaceflight handbooks (dating from the 1960s) SP-33 Orbital Flight Handbook (3 parts) SP-34 Lunar Flight Handbook (3 parts) SP-35 Planetary Flight Handbook (9 parts) These might be found in university aeronautics libraries or ordered through the US Govt. Printing Office (GPO), although more information would probably be needed to order them. M. A. Minovitch, _The Determination and Characteristics of Ballistic Interplanetary Trajectories Under the Influence of Multiple Planetary Attractions_, Technical Report 32-464, Jet Propulsion Laboratory, Pasadena, Calif., Oct, 1963. The title says all. Starts of with the basics and works its way up. Very good. It has a companion article: M. Minovitch, _Utilizing Large Planetary Perubations for the Design of Deep-Space Solar-Probe and Out of Ecliptic Trajectories_, Technical Report 32-849, JPL, Pasadena, Calif., 1965. You need to read the first one first to realy understand this one. It does include a _short_ summary if you can only find the second. Contact JPL for availability of these reports. "Spacecraft Attitude Dynamics", Peter C. Hughes 1986, John Wiley and Sons. "Celestial Mechanics: a computational guide for the practitioner", Lawrence G. Taff, (Wiley-Interscience, New York, 1985). Starts with the basics (2-body problem, coordinates) and works up to orbit determinations, perturbations, and differential corrections. Taff also briefly discusses stellar dynamics including a short discussion of n-body problems. COMPUTING PLANETARY POSITIONS More net references: Van Flandern & Pullinen, _Low-Precision Formulae for Planetary Positions_, Astrophysical J. Supp Series, 41:391-411, 1979. Look in an astronomy or physics library for this; also said to be available from Willmann-Bell. Gives series to compute positions accurate to 1 arc minute for a period + or - 300 years from now. Pluto is included but stated to have an accuracy of only about 15 arc minutes. _Interactive Computer Ephemeris_ (from the US Naval Observatory) distributed on IBM-PC floppy disks, $35 (Willmann-Bell). Covers dates 1800-2049. "Planetary Programs and Tables from -4000 to +2800", Bretagnon & Simon 1986, Willmann-Bell. Floppy disks available separately. "Fundamentals of Celestial Mechanics" (2nd ed), J.M.A. Danby 1988, Willmann-Bell. A good fundamental text. Includes BASIC programs; a companion set of floppy disks is available separately. "Astronomical Formulae for Calculators" (4th ed.), J. Meeus 1988, Willmann-Bell. "Astronomical Algorithms", J. Meeus 1991, Willmann-Bell. If you actively use one of the editions of "Astronomical Formulae for Calculators", you will want to replace it with "Astronomical Algorithms". This new book is more oriented towards computers than calculators and contains formulae for planetary motion based on modern work by the Jet Propulsion Laboratory, the U.S. Naval Observatory, and the Bureau des Longitudes. The previous books were all based on formulae mostly developed in the last century. Algorithms available separately on diskette. "Practical Astronomy with your Calculator" (3rd ed.), P. Duffett-Smith 1988, Cambridge University Press. "Orbits for Amateurs with a Microcomputer", D. Tattersfield 1984, Stanley Thornes, Ltd. Includes example programs in BASIC. "Orbits for Amateurs II", D. Tattersfield 1987, John Wiley & Sons. "Astronomy / Scientific Software" - catalog of shareware, public domain, and commercial software for IBM and other PCs. Astronomy software includes planetarium simulations, ephemeris generators, astronomical databases, solar system simulations, satellite tracking programs, celestial mechanics simulators, and more. Andromeda Software, Inc. P.O. Box 605 Amherst, NY 14226-0605 COMPUTING CRATER DIAMETERS FROM EARTH-IMPACTING ASTEROIDS Astrogeologist Gene Shoemaker proposes the following formula, based on studies of cratering caused by nuclear tests. (1/3.4) D = S S c K W : crater diameter in km g p f n (1/6) S = (g /g ) : gravity correction factor for bodies other than g e t Earth, where g = 9.8 m/s^2 and g is the surface e t gravity of the target body. This scaling is cited for lunar craters and may hold true for other bodies. (1/3.4) S = (p / p ) : correction factor for target density p , p a t t p = 1.8 g/cm^3 for alluvium at the Jangle U a crater site, p = 2.6 g/cm^3 for average rock on the continental shields. C : crater collapse factor, 1 for craters <= 3 km in diameter, 1.3 for larger craters (on Earth). (1/3.4) K : .074 km / (kT TNT equivalent) n empirically determined from the Jangle U nuclear test crater. 3 2 19 W = pi * d * delta * V / (12 * 4.185 * 10 ) : projectile kinetic energy in kT TNT equivalent given diameter d, velocity v, and projectile density delta in CGS units. delta of around 3 g/cm^3 is fairly good for an asteroid. An RMS velocity of V = 20 km/sec may be used for Earth-crossing asteroids. Under these assumptions, the body which created the Barringer Meteor Crater in Arizona (1.13 km diameter) would have been about 40 meters in diameter. More generally, one can use (after Gehrels, 1985): Asteroid Number of objects Impact probability Impact energy diameter (km) (impacts/year) (* 5*10^20 ergs) 10 10 10^-8 10^9 1 1 000 10^-6 10^6 0.1 100 000 10^-4 10^3 assuming simple scaling laws. Note that 5*10^20 ergs = 13 000 tons TNT equivalent, or the energy released by the Hiroshima A-bomb. References: Gehrels, T. 1985 Asteroids and comets. _Physics Today_ 38, 32-41. [an excellent general overview of the subject for the layman] Shoemaker, E.M. 1983 Asteroid and comet bombardment of the earth. _Ann. Rev. Earth Planet. Sci._ 11, 461-494. [very long and fairly technical but a comprehensive examination of the subject] Shoemaker, E.M., J.G. Williams, E.F. Helin & R.F. Wolfe 1979 Earth-crossing asteroids: Orbital classes, collision rates with Earth, and origin. In _Asteroids_, T. Gehrels, ed., pp. 253-282, University of Arizona Press, Tucson. Cunningham, C.J. 1988 _Introduction to Asteroids: The Next Frontier_ (Richmond: Willman-Bell, Inc.) [covers all aspects of asteroid studies and is an excellent introduction to the subject for people of all experience levels. It also has a very extensive reference list covering essentially all of the reference material in the field.] MAP PROJECTIONS AND SPHERICAL TRIGNOMETRY Two easy-to-find sources of map projections are the "Encyclopaedia Brittanica", (particularly the older volumes) and a tutorial appearing in _Graphics Gems_ (Academic Press, 1990). The latter was written with simplicity of exposition and suitability of digital computation in mind (spherical trig formulae also appear, as do digitally-plotted examples). More than you ever cared to know about map projections is in John Snyder's USGS publication "Map Projections--A Working Manual", USGS Professional Paper 1395. This contains detailed descriptions of 32 projections, with history, features, projection formulas (for both spherical earth and ellipsoidal earth), and numerical test cases. It's a neat book, all 382 pages worth. This one's $20. You might also want the companion volume, by Snyder and Philip Voxland, "An Album of Map Projections", USGS Professional Paper 1453. This contains less detail on about 130 projections and variants. Formulas are in the back, example plots in the front. $14, 250 pages. You can order these 2 ways. The cheap, slow way is direct from USGS: Earth Science Information Center, US Geological Survey, 507 National Center, Reston, VA 22092. (800)-USA-MAPS. They can quote you a price and tell you where to send your money. Expect a 6-8 week turnaround time. A much faster way (about 1 week) is through Timely Discount Topos, (303)-469-5022, 9769 W. 119th Drive, Suite 9, Broomfield, CO 80021. Call them and tell them what you want. They'll quote a price, you send a check, and then they go to USGS Customer Service Counter and pick it up for you. Add about a $3-4 service charge, plus shipping. A (perhaps more accessible) mapping article is: R. Miller and F. Reddy, "Mapping the World in Pascal", Byte V12 #14, December 1987 Contains Turbo Pascal procedures for five common map projections. A demo program, CARTOG.PAS, and a small (6,000 point) coastline data is available on CompuServe, GEnie, and many BBSs. Some references for spherical trignometry are: _Spherical Astronomy_, W.M. Smart, Cambridge U. Press, 1931. _A Compendium of Spherical Astronomy_, S. Newcomb, Dover, 1960. _Spherical Astronomy_, R.M. Green, Cambridge U. Press., 1985 (update of Smart). _Spherical Astronomy_, E Woolard and G.Clemence, Academic Press, 1966. PERFORMING N-BODY SIMULATIONS EFFICIENTLY "Computer Simulation Using Particles" R. W. Hockney and J. W. Eastwood (Adam Hilger; Bristol and Philadelphia; 1988) "The rapid evaluation of potential fields in particle systems", L. Greengard MIT Press, 1988. A breakthrough O(N) simulation method. Has been parallelized. L. Greengard and V. Rokhlin, "A fast algorithm for particle simulations," Journal of Computational Physics, 73:325-348, 1987. "An O(N) Algorithm for Three-dimensional N-body Simulations", MSEE thesis, Feng Zhao, MIT AILab Technical Report 995, 1987 "Galactic Dynamics" J. Binney & S. Tremaine (Princeton U. Press; Princeton; 1987) Includes an O(N^2) FORTRAN code written by Aarseth, a pioneer in the field. Hierarchical (N log N) tree methods are described in these papers: A. W. Appel, "An Efficient Program for Many-body Simulation", SIAM Journal of Scientific and Statistical Computing, Vol. 6, p. 85, 1985. Barnes & Hut, "A Hierarchical O(N log N) Force-Calculation Algorithm", Nature, V324 # 6096, 4-10 Dec 1986. L. Hernquist, "Hierarchical N-body Methods", Computer Physics Communications, Vol. 48, p. 107, 1988. INTERPRETING THE FITS IMAGE FORMAT If you just need to examine FITS images, use the ppm package (see the comp.graphics FAQ) to convert them to your preferred format. Failing that, the basic reference for FITS may be found in the following 3 papers: Wells, D. C., Greisen, E. W., and Harten, R. H., "FITS: a flexible image transport system," Astronomy and Astrophysics Supplement Series, 44, 363-370, 1981. Grosbol, P., Harten, R. H., Greisen, E. W., and Wells, D. C., "Generalized extensions and blocking factors for FITS," Astronomy and Astrophysics Supplement Series, 73, 359-364, 1988 Harten, R. H., Grosbol. P., Greisen, E. W., and Wells, D. C., "The FITS tables extension, Astronomy and Astrophysics Supplement Series, 73, 365-372, 1988. A DRAFT document describing FITS and the Floating Point Agreement defining FP storage formats is available by anonymous FTP from nssdca.gsfc.nasa.gov (128.183.36.23). Get ANON_DIR:[FITS]README.;1 to begin with. There are known to be errors and ambiguities in this document, so it should not be used as a fundamental reference. Questions should be sent by email to the FITS support office (bschlesinger@nssdca.gsfc.nasa.gov) or telephone at (301)-513-1634 A FORTRAN library for reading and writing FITS files is available by anonymous FTP from tetra.gsfc.nasa.gov (128.183.8.77) in directory pub/fitsio3. Contact the author, William Pence (pence@tetra.gsfc.nasa.gov) for more details. SKY (UNIX EPHEMERIS PROGRAM) The 6th Edition of the Unix operating system came with several software systems not distributed because of older media capacity limitations. Included were an ephmeris, a satellite track, and speech synthesis software. The ephmeris, sky(6), is available within AT&T and to sites possessing a Unix source code license. The program is regarded as Unix source code. Sky is <0.5MB. Send proof of source code license to E. Miya MS 258-5 NASA Ames Research Center Moffett Field, CA 94035-1000 eugene@orville.nas.nasa.gov THREE-DIMENSIONAL STAR/GALAXY COORDINATES To generate 3D coordinates of astronomical objects, first obtain an astronomical database which specifies right ascension, declination, and parallax for the objects. Convert parallax into distance using the formula in part 6 of the FAQ, convert RA and declination to coordinates on a unit sphere (see some of the references on planetary positions and spherical trignometry earlier in this section for details on this), and scale this by the distance. Two databases useful for this purpose are the Yale Bright Star catalog (sources listed in FAQ section 3) or "The Catalogue of Stars within 25 parsecs of the Sun" (in pub/SPACE/FAQ/stars.data and stars.doc on ames.arc.nasa.gov). NEXT: FAQ #5/15 - References on specific areas ------------------------------ End of Space Digest Volume 15 : Issue 491 ------------------------------