***** File AAREADME.TXT This compact disc (CD-ROM) is one of a 5-disc set containing digital data obtained through the efforts of all the International Halley Watch (IHW) Disciplines and their corresponding Networks. Because of their multi-Discipline composition, the five discs, which are Volumes 19-23 in the total set of IHW CD-ROMs, have become known informally as the "mixed discs." Volumes 1-18 are dedicated to the Large-Scale Phenomena Discipline and its very large image files, which have been deposited on disc in compressed form. Finally, Volume 24 contains data from the IHW "Trial Run" targets--comets P/Crommelin and Giacobini-Zinner--and Volumes 25-26 are devoted to space data returned by the Halley intercept spacecraft and the International Cometary Explorer (ICE). In addition to the data themselves, this disc contains a wide variety of supporting files and tools for the Archive user; the major categories are documentation, ephemeris information, searchable tables and indices, and software (source code as well as executable modules). These have been organized into four principal directories one level below the root: DOCUMENT, EPHEM, INDEX, and SOFTWARE. It is suggested that the Archive user review the document files listed below before roaming through the multi-level data directories: \DOCUMENT\HALGUIDE.TXT Brief guide to use of discs \DOCUMENT\CDTREE.TXT Schematic, annotated layout of disc \DOCUMENT\VOLINFO.TXT More complete description of disc, history of IHW CD-ROM generation \DOCUMENT\APPENDIX\*.APX Appendices for (all) nine IHW Disciplines \INDEX\INDXINFO.TXT Description of basic indices \INDEX\NETABLES\NETINFO.TXT Description of "printed archive" and Discipline-specific indices \SOFTWARE\SOFTINFO.TXT Brief enumeration of software on disc The time period covered by this disc is Feburary 10, 1986 through April 13, 1986 inclusive. Data from all nine IHW Disciplines, except Meteor Studies, are included (the Meteor data are contained on the last "mixed disc," Volume 23). Astrometry data from the previous apparitions of 1835 and 1910 have been put on this disc, as well as data from the "current" (1985-86) apparition. Data preparation for the IHW Archive has been the work of many people within each Discipline, of the Lead Center personnel at JPL, and of those at NASA/GSFC who actually generated the CD-ROMs. Efforts at the Discipline level are described in the Appendix files in the \DOCUMENT\APPENDIX directory, and a history of IHW CD-ROM generation is given in the ACKNWLDG.TXT file of the root directory. Although many people have been involved in this project (including the observers), the individuals listed below were responsible for actually making the discs and they accept responsibility for any errors in disc format and/or layout, but not actual file content. All of the text files on this disc have fixed length records padded to either 80 or 132 bytes per record. The last two characters of each record are a carriage return and line feed. This has been done to files with the following extensions (*.txt, *.str, *.apx, and *.lbl). M. Niedner, Jr. E. Grayzeck, Jr. IHW Discipline Specialist Small Bodies Node of for Large-Scale Phenomena Planetary Data System Laboratory for Astronomy Astronomy Department and Solar Physics University of Maryland Code 684.1 College Park, MD 20742 NASA/GSFC Greenbelt, MD 20771 D. Klinglesmith III A. Warnock III IHW Team Member for IHW Team Member for Large-Scale Phenomena Large-Scale Phenomena Laboratory for Astronomy ST Systems Corp. and Solar Physics Code 681 Code 684.0 NASA/GSFC NASA/GSFC Greenbelt, MD 20771 Greenbelt, MD 20771 M. Aronsson IHW Lead Center Jet Propulsion Laboratory MS 169-237 4800 Oak Grove Dr. Pasadena, CA 91109