by Benjamin Apthorp Gould
Reprinted and Updated by
Frederick Pilcher
Benjamin Apthorp Gould was a giant of late 19th century astronomy, whose
legacy extends into the 21st century. He set constellation boundaries for
southern hemisphere constellations which with only a few small changes were
accepted when they were permanently fixed by the International Astronomical
Union in 1930. He was first to call attention to the belt of bright stars
through the southern Milky Way which is still termed "Gould's belt." And he
published a catalog of positions of southern stars, the Uranometria Argentina,
of very high accuracy and completeness. Yet as a historical figure he has been
undeservedly nearly forgotten. To restore his historical role in the
consciousness of 21st century astronomers, and to provide a simple number
identification scheme for all naked eye stars in southern hemisphere
constellations, this writer presents a reprint and update of his Uranometria
Argentina.
In 1879 Benjamin Apthorp Gould published the Uranometria Argentina: Vol. 1
of Resultados del Observatorio Nacional Argentino en Cordoba. It includes 7756
southern hemisphere stars within 100 degrees of the south pole whose positions
he himself had measured at the Observatorio Nacional Argentino in Cordoba.
This he intended to be complete to all naked eye stars to magnitude 7.0,
although comparison of his magnitudes to modern photoelectric magnitudes shows
his were systematically 0.2 to 0.6 magnitudes too faint, more so in some
constellations than in others.
This catalog is somewhat analogous to John Flamsteed's Catalogus
Brittanicus prepared more than 150 years earlier for stars visible from
Greenwich. Flamsteed's catalog omits a number of naked eye stars magnitudes
4.5 and fainter, and contains many errors which later stellar cartographers
have largely corrected. Gould's Uranometria Argentina, however, is essentially
complete to his stated magnitude limit. A very small number of errors were in
subsequent decades published by himself and others. Gould, like Flamsteed,
numbers his stars separately for each constellation and, except in some cases
as explained in the next paragraph, in sequence of increasing right ascension
in the coordinates of his epoch, 1875. Flamsteed's numbers have been included
in most modern star catalogs, atlases, and planetarium-type programs, and are
valuable to designate naked eye stars beyond the limits of Bayer letters.
Regrettably Gould's star designations have disappeared from modern literature.
Especially for observers of southern hemisphere stars the loss of this simple
nomenclature is unfortunate, as without it many naked eye stars can only be
identified with their awkward 5 or 6 digit numbers from the HD (Henry Draper),
SAO (Smithsonian Astrophysical Observatory), or other catalogs.
In the Uranometria Argentina Gould lists many instances of two or more
close together stars. These include some stars which he considered fainter
than magnitude 7.0 which were close to other stars and for which the combined
light he considered magnitude 7.0 or brighter. To these Gould did not assign
numbers. In the Uranometria Argentina these are connected by curly brackets,
which are not easily represented on computer text files. In this updated
listing stars associated with other stars the curly brackets are replaced with
the symbol #. In some cases Gould's listing of stars in sequence of increasing
right ascension is interrupted to allow two or more stars connected by curly
brackets, or the symbol # in this updated version, to appear on consecutive
lines. To follow the Uranometria Argentina faithfully they are included in
this listing.
Gould catalog star numbers are almost unknown in 20th and early 21st
century popular star catalogs, atlases, and planetarium programs. Indeed, the
Gould catalog might have vanished from modern astronomical consciousness except
for the use of Gould catalog numbers in the Fundamental Katalog (FK) series by
the Astronomische Rechen-Institute and in the Astronomical Almanac of the U. S.
Naval Observatory prior to the year 1979 for extremely precise star positions
of fundamental stars. These appeared with the letter G following the star
number from the Gould Uranometria Argentina catalog, and should be contrasted
with Flamsteed numbers which did not carry any letter following the Flamsteed
number. For example in Orion the star Pi6 carries the Flamsteed number 10 and
the Gould number 22G. The star o is Flamsteed 22 and Gould 61G. Any modern
use of Gould star numbers should always be followed by the letter G to
unambiguously distinguish Flamsteed unlettered numbers from Gould G numbers.
This practice should be followed even for far southern constellations which
have no Flamsteed numbers because they were permanently below the horizon at
Flamsteed's Greenwich observatory.
In the 21st century Gould's Uranometria Argentina can be found only in a
few libraries with specialized collections. To make them available once more
to star enthusiasts this author has laboriously copied all the tabulated
information from the Uranometria Argentina into digital format with the
capability of printout or digital manipulation for exporting elsewhere.
This work is more than just a reprint of the Uranometria Argentina. For
all the stars listed in this Catalog the author has included the modern J2000
coordinates, photoelectric magnitudes, spectral classes, and both their HD and
SAO numbers. This is in addition to all the information in Gould's Uranometria
Argentina including his designations from historic catalogs, coordinates in the
equinox of 1875, and Gould's original magnitude estimates. Gould was very
careful to determine magnitudes, and especially to look for variable stars.
Compared with modern magnitudes his tend to be systematically 0.2 to 0.6 too
faint, varying somewhat among different constellations, with an additional
random error around 0.3 magnitudes rms.
As in Gould's original catalog, each constellation is listed separately
and within each constellation the stars are listed in the same sequence as in
the Uranometria Argentina. The columns in the tabulation are from the left the
Gould number, Flamsteed number and letter, if any, modern photoelectric
magnitude, spectral class, right ascension in hours, minutes, and seconds,
declination in hours, minutes, and seconds, both in J2000 coordinates, HD
catalog number, SAO catalog number. For cases in which the full spectral
class requires more than the eight character column width provided for spectral
class, an abbreviated and usually less precise form written with the * symbol
referrs to the complete form in the Notes following the star list for each
constellation. An asterisk standing alone in this column indicates that no
spectral class is available. The symbol v following the magnitude indicates a
variable star with the stated magnitude in most cases the brightest observed,
and the symbol v? indicates possibly variable. Because the degree symbol for
declination is not represented in digital alphanumeric format, the h, m, s for
right ascension and degree symbol, ', " for declination are omitted. The user
should recognize the usual format of representation of these quantities and be
able to correctly interpret their meaning without these symbols. Following
these data shown in current catalogs are the original data from Gould's
Uranometria Argentina. These are intended to be an exact duplication of the
numerical data in the Uranometria Argentina except for error corrections
identified by asterisks. In sequence from left to right these are: Gould's
references to star designations from earlier catalogs, the right ascension in
hours, minutes, and seconds, declination in degrees and minutes to the nearest
0.1 minute, both in the equator and equinox of 1875, magnitude as determined by
Gould, and notes for some stars. Symbols in the Notes column include dpl. for
double stars with the magnitudes of the components in sequence of increasing
right ascension; var. for variable stars with the magnitude range of variation
in some instances; var? for stars which Gould considered as possibly variable;
r to denote red stars; rr to denote excessively red stars; and c to denote
otherwise colored stars. It should be noted that Gould also stated Flamsteed
numbers and letters along with other catalog references. As these are all
given in earlier columns, there is no need to repeat them here. It should be
noted that in Gould's Uranometria Argentina, the - sign was omitted without
ambiguity from all declinations -10 degrees and farther south, as the catalog
contained no stars north of +10 degrees declination. The + sign was omitted
from declinations for stars in constellations lying enirely north of the
celestial equator. For the convenience of 21st century users, in this work the
+ and - signs have been restored to Gould's 1875 declinations for all stars for
which they were omitted. Except for some faint stars which Gould connected
with braces to nearby stars and for many of which he did not assign numbers,
within each constellation Gould arranged the stars in sequence of increasing
right ascension in 1875 coordinates. Because precession in right ascension is
dependent upon the tangent of the declination and is greater at greater angles
from the celestial equator, the reader will note that the numerical sequence of
Gould numbers is not strictly a sequence of increasing right ascension in J2000
coordinates.
The reader will note many asterisks in the star tabulations for each of
the separate constellations. Each of these is explained in another listing
below the star tabulation. While many of these should be self-explanatory, the
user should use special caution with the following. A * in the Gould number
column indicates that Gould did not provide a number for this star, usually
because he considered it fainter than magnitude 7.0, although he included all
other information customarily provided for individual stars. A * following the
letter indicated that Gould did NOT include it in the Uranometria Argentina,
often because Gould did not approve of lettering stars fainter than magnitude
6.0. The letter has been restored here because it appears in some modern
catalogs and star atlases, and its inclusion may be helpful to some modern
users. In some other cases a variable star designation was assigned after the
Uranometria Argentina was published and is included here although it does not
appear in in Gould's original catalog. A * following the spectral class
indicates that the spectral class has too many characters to fit in the 8
character column width and that the representation here is an abbreviation, or
if no spectral class is provided here it is not available. A * following the
right ascension or declination in 1875 coordinates indicates that a correction
to the value in the Uranometria Argentina has been published. Here the
corrected value is shown in the tabulation with a reference to the value in the
original Uranometria Argentina from which it was corrected. A # following the
magnitude indicates this star is one of two or more stars linked by a brace in
the Uranometria Argentina.
One page of errata was published with the original catalog. In addition,
two publications supply further corrections to the printed work. These are by
B. A. Gould, Astronomische Nachrichten 116, pp 379-382 (1887AN....116..379G),
and by T. W. Backhouse, Astronomical Journal 12, 112 (1892AJ.....12Q.112B).
To simplify use of this expansion of the original catalog, the corrected values
are written into the tables with footnotes to the original values. All of
these, and a few others, mostly typographical misprints found by the present
author, are presented in this digital version.
In the Uranometria Argentina Gould frequently used braces to associate two
or more stars which were close together in the sky. Digital representation
prevents the use of this original notation and is replaced here by # symbols.
But all such associations are stated for each constellation in the footnotes
following the star lists as "connected by braces." In some cases Gould
assigned a combined magnitude for the set of brace-associated stars. Readers
will note that in a majority of cases the combined magnitude is fainter than
would be found by the modern formula for the addition of star magnitudes. As
one purpose of this work is to reprint the Gould Uranometria Argentina catalog,
these incorrect combined magnitudes have been allowed to stand. Readers
wishing to make corrections should use the modern photoelectric magnitudes
rather than Gould's original magnitudes.
The preparation of this "Updated Uranometria Argentina" was all done by
hand entry. Some errors of transcription are inevitable. While these will
cause the user some inconvenience, there is enough redundancy in the tables
in principle to correct them. Each star has a unique data set consisting of
J2000 coordinates, magnitude, spectral class, HD and SAO numbers. A
typographical error will usually cause one of these parameters to be
inconsistent with all the others in the set and therefore be capable of
identification. The modern J2000 coordinates and Gould 1875 coordinates should
be consistent within a few arcseconds in most cases after applying precession
and proper motion between these years.
The Astronomical Almanac published annually by the U. S. Naval Observatory
carried Gould number star designations for several stars in the "Apparent
Places of Fundamental Stars" section until the year 1980. The reorganization
of the Astronomical Almanac which occurred the next year eliminated these
designations. The FK5 catalog of 1535 fundamental stars published annually by
the Astronomisches Rechen-Institute, Heidelberg, Germany, continued the use
of Gould number designations through the year 1999.
It is noteworthy that Gould assigned letters to previously unlettered
5th magnitude stars which Gould considered worthy of having letters, and
unlike his numbers these have survived in modern literature. In his
Uranometria Argentina Gould dropped some previously assigned letters from stars
which he considered fainter than magnitude 6. Those letters which still
appear in some modern atlases and catalogs are restored, although denoted with
asterisks, in this updated version. Very significant for the history of
astronomy is that Gould defined constellation boundaries south of +10 degrees
declination which with very few exceptions were those adopted and permanently
fixed by the IAU in 1930.
It would be a simple matter to add the Gould designations of stars from
the digital version of this work to lists of other designations in planetarium
programs, as modern precise magnitudes, spectral classes, coordinates for the
year 2000, and identifications with other catalogues are included. The author
encourages producers of these planetarium programs to do this. Once again, all
Gould catalog numbers in such a presentation should always be followed by the
letter G.
In the Uranometria Argentina Gould arranged his constellations in
sequence of increasing distance from the South Celestial Pole and provided a
number for each constellation in this sequence. Thus there is published
1. - Octans; 2. - Mensa; 3. - Hydrus, and so forth. In this update of the
original the constellations are rearrangeded to alphabetical sequence, but in
each case the original constellation number assigned by Gould is included in
the constellation name heading.
Gould included 66 constellations all or part of which are south of +10
degrees declination. The left column list rearranges the original sequence
alphabetically. The right column list retains Gould's original sequence in
terms of increasing distance from the south celstial pole.