% % WDCPAPER.TEX % % Paper sent to the World Data Center describing the catalogues of % constellation boundary data. % % A C Davenhall (ROE). 1/8/88. % A C Davenhall (ROE). {Revised} 20/2/90. % \documentstyle[12pt]{article} \title{A Catalogue of Constellation Boundary Data} \author{A.C. Davenhall \thanks{Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, Scotland.} \\ S.K. Leggett \thanks{Dept. of Astronomy, University of Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ, Scotland.} \thanks{Present address, US Naval Observatory, Flagstaff, Arizona, USA.} } \date{February 1990} \setcounter{secnumdepth}{3} \setcounter{tocdepth}{3} % % Start document. % \begin{document} \maketitle \begin{abstract} A computer readable catalogue of constellation boundary data is presented in a form suitable for the construction of star charts and atlases. Two files are available, one for equator and equinox 1875 and the other for equator and equinox 2000. \end{abstract} \section{INTRODUCTION} The definitive list of constellation boundary data was published by Delporte (1930). A computer-readable catalogue compiled from these data has been produced by Roman (1987) and is available from the International Network of Astronomical Data Centers (catalogue number 6042). However, the format of this catalogue has been chosen to facilitate locating the constellation in which a given object lies and is unsuited to the construction of star charts and atlases. The present catalogue was also constructed from Delporte's lists, but the files are arranged in a format suitable for constructing star charts and atlases. Two files are available in a computer-readable form. The first gives the boundaries as delineated by Delporte, in their original orientation, 1875. The second file gives the boundaries computed for equator and equinox 2000. In equator and equinox 1875 the lines joining the corners of the constellations were great circles of right ascension and parallels of declination. However, precession to equator and equinox 2000 distorts the boundaries so that they no longer lie along lines of constant right ascension or declination. Thus, prior to precession to equator and equinox 2000, points were interpolated at one degree intervals along the boundaries in order that they should continue to enclose the same area of sky (and thus the same set of stars). \section{THE CATALOGUE} Brief details of the two files of the catalogue are given below. \subsection{Equator and equinox 1875 file} The data in this file was taken directly from Delporte with the exception that several extra points were added to the constellation Octans (which covers the South Pole) in order to facilitate plotting in some projections. These extra points `traverse' the line of 0hr right ascension to the Pole and `return' at 24hr. The file consists of the right ascension and declination of every corner of every constellation. Each record consists of a single point along the constellation boundary and contains the right ascension and declination of the point and an abbreviation identifying the constellation of which it is a part. The abbreviations used to identify each constellation are taken from Delporte, and for completeness they are listed together with the full name in Table 1. All the abbreviations consist of three characters except those for Serpens Caput and Serpens Cauda which contain four. All records referring to a given constellation occur contiguously in the file. Successive records correspond to successive points along the constellation boundary. The last point in the constellation should be joined to the first. Table 2 gives details of the structure of each record. The following fragment of FORTRAN could be used to read a single record from the file \begin{verbatim} REAL RA, DEC CHARACTER*4 CONNAM . . READ(13, 1000) RA, DEC, CONNAM 1000 FORMAT(F8.5, 1X, F9.5, 1X, A4) . . \end{verbatim} \subsection{Equator and equinox 2000 file} In equator and equinox 1875, lines joining the corners of constellations are either great circles of right ascension or parallels of declination. When the coordinates are converted to equator and equinox 2000, the boundaries are distorted by precession so that they no longer lie along lines of constant right ascension or declination. In order that the new boundaries should enclose the same area of sky (and thus include the same stars) it is necessary that points should be interpolated along the boundary prior to calculating the precession. Thus the orientation 2000 file was generated from the orientation 1875 file with points interpolated at one-degree intervals along the boundaries. When the file is used to construct a chart, a smooth curve should be drawn through the interpolated points (but obviously not through those original points that define corners). Records in the file are ordered into constellations and successive corners within each constellation in a similar fashion to the orientation 1875 file. Table 3 lists the details of the structure of each record. Like the orientation 1875 file, each record contains the right ascension and declination of a point together with an abbreviation for the constellation to which it belongs. However an additional field indicates whether the point is an original point taken directly from Delporte (code `O') or an interpolated point (code `I'). It should be noted that original points can be points along a meridian or parallel where three constellations meet as well as corners. The following fragment of FORTRAN could be used to read a single record from the file \begin{verbatim} REAL RA, DEC CHARACTER*4 CONNAM CHARACTER*1 TYPE . . READ(13, 1001) RA, DEC, CONNAM, TYPE 1001 FORMAT(F10.7, 1X, F11.7, 1X, A4, 1X A1) . . \end{verbatim} \section{DISCUSSION} The present catalogue of constellation boundary data is complementary to that of Roman (1987). Roman's catalogue should be used to determine which constellation an object lies in. The present catalogue is more suited to the construction of star charts and atlases. \section{ACKNOWLEDGEMENTS} We are grateful to Mr D.A. Pickup for useful discussions about the format of Delporte's lists and the effect of precession on the shape of the constellation boundaries and to Dr W.H. Warren Jr for several useful suggestions. All computations were carried out on the Starlink VAX 11/780 at the Royal Observatory Edinburgh, and the catalogue was precessed using the SCAR astronomical database software available within the Starlink software collection. This work was carried out as part of a contract with the Edinburgh publishers John Bartholomew and Son Ltd. to provide data for a revised edition of `Norton's Star Atlas'. \section{REFERENCES} Delporte, E. 1930, {\it Delimitation Scientifique des Constellations} (Cambridge: Cambridge University Press). \\[2.0ex] Roman, N.G. 1987, {\it Publ. Astron. Soc. Pac.} \underline{99}, pp695-699. % % Constellation names and abbreviations. % \begin{table} \begin{tabular}{|l|l|l|l|l|}\hline Abbreviation & Constellation Name & & Abbreviation & Constellation Name \\ \hline AND & Andromeda & & DOR & Dorado \\ ANT & Antila & & DRA & Draco \\ APS & Apus & & EQU & Equuleus \\ AQR & Aquarius & & ERI & Eridanus \\ AQL & Aquila & & FOR & Fornax \\ ARA & Ara & & GEM & Gemini \\ ARI & Aries & & GRU & Grus \\ AUR & Auriga & & HER & Hercules \\ BOO & Bootes & & HOR & Horologium \\ CAE & Caelum & & HYA & Hydra \\ CAM & Camelopardis & & HYI & Hydrus \\ CNC & Cancer & & IND & Indus \\ CVN & Canes Venatici & & LAC & Lacerta \\ CMA & Canis Major & & LEO & Leo \\ CMI & Canis Minor & & LMI & Leo Minor \\ CAP & Capricornus & & LEP & Lepus \\ CAR & Carina & & LIB & Libra \\ CAS & Cassiopeia & & LUP & Lupus \\ CEN & Centaurus & & LYN & Lynx \\ CEP & Cepheus & & LYR & Lyra \\ CET & Cetus & & MEN & Mensa \\ CHA & Chamaeleon & & MIC & Microscopium \\ CIR & Circinus & & MON & Monoceros \\ COL & Columba & & MUS & Musca \\ COM & Coma Berenices & & NOR & Norma \\ CRA & Corona Australis & & OCT & Octans \\ CRB & Corona Borealis & & OPH & Ophiuchus \\ CRV & Corvus & & ORI & Orion \\ CRT & Crater & & PAV & Pavo \\ CRU & Crux & & PEG & Pegasus \\ CYG & Cygnus & & PER & Perseus \\ DEL & Delphinus & & PHE & Phoenix \\ \hline \end{tabular} \begin{center} Table 1: Abbreviations for constellation names. \end{center} \end{table} \begin{table} \begin{tabular}{|l|l|l|l|l|}\hline Abbreviation & Constellation Name & & Abbreviation & Constellation Name \\ \hline PIC & Pictor & & SEX & Sextans \\ PSC & Pisces & & TAU & Taurus \\ PSA & Pisces Austrinus & & TEL & Telescopium \\ PUP & Puppis & & TRI & Triangulum \\ PYX & Pyxis & & TRA & Triangulum Australe \\ RET & Reticulum & & TUC & Tucana \\ SGE & Sagitta & & UMA & Ursa Major \\ SGR & Sagittarius & & UMI & Ursa Minor \\ SCO & Scorpius & & VEL & Vela \\ SCL & Sculptor & & VIR & Virgo \\ SCT & Scutum & & VOL & Volans \\ SER1 & Serpens Caput & & VUL & Vulpecula \\ SER2 & Serpens Cauda & & & \\ \hline \end{tabular} \begin{center} Table 1 (continued): Abbreviations for constellation names. \end{center} \end{table} % % details for equator and equinox 1985 file. % \begin{table} \begin{tabular}{|l|l|}\hline Number of records & 1566 \\ Record size (bytes) & 25 \\ \hline \end{tabular} \begin{tabular}{|l|l|l|l|}\hline Field & Units & Starting byte & Format \\ \hline Right ascension & Decimal hours & 1 & F8.5 \\ Declination & Decimal degrees & 10 & F9.5 \\ Constellation & & 20 & A4 \\ Type of point & & 25 & A1 \\ \hline \end{tabular} \begin{center} Table 2: Format of equator and equinox 1875 file. \end{center} \end{table} % % details of equator and equinox 2000 file. % \begin{table} \begin{tabular}{|l|l|}\hline Number of records & 13422 \\ Record size (bytes) & 29 \\ \hline \end{tabular} \begin{tabular}{|l|l|l|l|}\hline Field & Units & Starting byte & Format \\ \hline Right ascension & Decimal hours & 1 & F10.7 \\ Declination & Decimal degrees & 12 & F11.7 \\ Constellation & & 24 & A4 \\ Type of point & & 29 & A1 \\ \hline \end{tabular} \begin{center} Table 3: Format of equator and equinox 2000 file. \end{center} \end{table} \end{document}