VI/42 Identification of a Constellation From Position (Roman 1987)
Identification of a Constellation from a Position
Roman N. G.
<Pub. Astron. Soc. Pac. 99, 695, (1987)>
=1987PASP...99..695R 1987PASP...99..695R
ADC_Keywords: Constellations
Description:
A table of constellation boundaries was rearranged to permit the
rapid identification of the constellation to which a position refers.
A software program is provided to precess positions at another
equinox to those at 1875.0.
Introduction:
Barry Rappaport put the list of constellation boundaries that was
published in 1930 (Delporte 1930) into electronic form. This form
made it convenient to manipulate the data into an arrangement that
is easier to use for finding a constellation from a position. The
southern boundaries of each constellation are listed in order of
declination and then by the eastern terminus of each declination arc.
A program, in FORTRAN77, for determining the constellation using the
data in data.dat is provided in two forms. Comments describe
the format in which the positions must be entered. The main program is
followed by a precession subroutine which permits the use of positions at
any epoch.
The file data.dat is a list of constellation boundaries in the form
Lower Right Ascension, Upper Right Ascension, Lower Declination,
three letter abbreviation for the Constellation.
The following is an example of the output of the program:
RA = 9.0000 DEC = 65.0000 IS IN CONSTELLATION UMa
RA = 23.5000 DEC = -20.0000 IS IN CONSTELLATION Aqr
RA = 5.1200 DEC = 9.1200 IS IN CONSTELLATION Ori
RA = 9.4555 DEC = -19.9000 IS IN CONSTELLATION Hya
RA = 12.8888 DEC = 22.0000 IS IN CONSTELLATION Com
RA = 15.6687 DEC = -12.1234 IS IN CONSTELLATION Lib
RA = 19.0000 DEC = -40.0000 IS IN CONSTELLATION CrA
RA = 6.2222 DEC = -81.1234 IS IN CONSTELLATION Men
END OF INPUT POSITIONS AFTER: RA = 6.2222 DEC = -81.1234
THE EQUINOX FOR THESE POSITIONS IS 1950.0
A C version of the program for those who have not access to a f77
compiler is also available.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
program.f 76 127 FORTRAN version of the software
program.c 77 156 C version of the software
data.dat 29 357 The data file with constellation boundaries
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Byte-by-byte Description of file: data.dat
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Bytes Format Units Label Explanations
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2- 8 F7.4 h RA_low Lower right ascension range, equinox=1875
10-16 F7.4 h RA_up Upper right ascension range, equinox=1875
18-25 F8.4 deg DE_low Lower (southern) declination, equinox=1875
27-29 A3 --- const Constellation name
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History:
* 30-Dec-1999: one line (#229) was corrected by Nancy G. Roman
References:
Delporte, E. 1930, Delimitation Scientifique des Constellations,
Cambridge: Cambridge U. Press
Roman N.G. 1987, Publ. Astron. Soc. Pacific, 99, 695-699
(End) Nancy Grace Roman [ADC/SSDOO] 22-Feb-1996