Catalog of Positions of Infrared Stellar Sources
-- Original 1994 information
Readers should understand that the CPIRSS catalog has been
updated since the writing of the following document. Hence, some of
the information in this document is outdated or repeated elsewhere.
However, since much of the initial work
on this project was performed in 1994, it was decided to give the
project report from that time in its entirety.
THE U.S. NAVAL OBSERVATORY CATALOG
OF POSITIONS OF INFRARED STELLAR SOURCES
1994 VERSION
Robert B. Hindsley and Robert S. Harrington*
*Deceased 23 Jan 1993
Astrometry Deptartment
U.S. Naval Observatory
Washington, DC 20392-5420
ABSTRACT: Star identifications in the IRAS Point Source Catalog
have been combined with optical positions from 4 astrometric catalogs to
yield a catalog with positional accuracies of about 0.2 arcsecond for
33,678 infrared sources. The identification of IRAS sources with bright
optical stars has been checked by requiring the color V-[12] (with [12]
being a magnitude derived from the IRAS flux) to be consistent with the
optical colors or spectral type. Observed V-[12] colors several
magnitudes redder than predicted from optical colors have usually been
interpreted as evidence of excess 12 micron flux, but many stars with
such colors are shown also to have an overly red V-K color. A
K magnitude (2.2 microns) has been estimated using the 12-micron flux
and the spectral type or observed optical color for the the 18,525 stars
that have no evidence of an unusual 12-micron flux.
1. INTRODUCTION
The Infrared Astronomical Satellite (IRAS) carried out an all-sky survey
at 12, 25, 60, and 100 microns. Approximately 250,000 point sources
were identified. However, by the standards of optical astrometry, the
positions of these sources are poorly determined, with errors of tens of
arcseconds. Optical astrometric catalogs such as the ACRS (Corbin &
Urban 1990) have errors in position of about 0.2 arc seconds, some two
orders of magnitude less than the IRAS position errors.
Many of the sources in the IRAS Point Source Catalog (1987, henceforth
PSC) have been identified as stars. SAO numbers are given for
approximately 1/8 of the entries in the PSC. Almost all of these stars
have positions given in optical astrometric catalogs. Thus it is possible to
construct a higher quality astrometric catalog of infrared sources by
combining these positions with the IRAS identifications.
Furthermore, if the spectral type or suitable photometry is available for
the star, the identification of IRAS sources with particular stars can be
confirmed. Because the IRAS positions have such large errors, the
identifications provided in the PSC are suspect. The V-[12] color, with
[12] being a magnitude determined from the 12-micron flux, is very
sensitive to temperature. If the optical identification of an IRAS source
is correct, the V-[12] color should be consistent with optical colors or
spectral type, with due allowance made for interstellar reddening.
Section 2 of this paper describes the various optical astrometric catalogs
that provided positions for the PSC sources. Section 3 deals with the
confirmation of identification based on color. In Section 4 the results of
the confirmation are discussed. Section 5 describes the estimation of
Johnson system K magnitudes for those stars with confirmed
identifications. Most of the catalog data needed for this work was taken
from the Astronomical Data Center CDROM "Selected Astronomical
Catalogs" (ADC 1991; henceforth CDROM).
2. OPTICAL ASTROMETRY
There are 34,438 stars with SAO identifications in the PSC. For
purposes of cross-referencing, the Durchmusterung (DM) catalog
number was obtained from the SAO/J2000/DM/HD/GC Cross Reference
Index (Roman, Warren, & Schofield 1991). For most stars south of -52
degrees, this number is the Cape Photographic Durchmusterung (CPD)
number. For stars north of -23 degrees, the number is from the Bonner
Durchmusterung or Southern Durchmusterung (henceforth BD for
both). In between, the DM number is from the Cordoba
Durchmusterung (CD). Stars with a single entry in the SAO and
multiple entries in the DM catalogs, or multiple entries in the SAO
catalog corresponding to one DM entry, were eliminated from further
consideration.
There were 34,407 stars with DM identifications. Four astrometric
catalogs were then searched for positions for these stars. Positions taken
from the FK5 (Fricke et. al. 1988) and the FK5 Extension (Fricke,
Schwan, & Corbin 1991) have errors at 1992 of 0.10 and 0.14 arcsecond
respectively, were the most accurate, and were favored over positions
from the other catalogs. The International Reference Stars catalog
(IRS; Corbin 1978, Corbin & Urban 1990) consists of those stars with
sufficient transit circle observations to define proper motions and
exhibits errors at 1992 of 0.20 arcseconds. The Astrographic Catalog
Reference Stars catalog (ACRS; Corbin & Urban 1990) is the next most
accurate astrometric catalog, with an error at 1992 of 0.21 arcseconds.
All of the determinations of positions and proper motions in the ACRS
include photographic data. The ACRS and FK5 Extension were
supplied by T. Corbin and S. Urban of the U.S. Naval Observatory. The
FK5 and the IRS were taken from the CDROM. Four FK5 stars have
incorrect DM numbers on the CDROM. The FK5 numbers for these
stars, with the correct DM number following in parentheses, are: 655
(BD+55 1944); 833 (BD+32 4349); 1387 (BD-15 3965); and 1527
(BD-12 5683). Some identifications of ACRS stars with DM numbers
were also revised with data from Roman (1993).
Of the IRAS PSC stars with Durchmusterung identifications, 33,678
have a position in one of the optical catalogs. The accuracy of the
catalog positions is the same as the source catalogs, about 0.2 arcseconds.
3. COLOR CONFIRMATION
Waters, Cote, and Aumann (WCA; 1987) compared V-[12] observed
colors for those IRAS sources also found in the Bright Star (BS) Catalog
(Hoffleit & Jaschek 1982) to more traditional color indices such as B-V.
They chose only those stars that had precise photometry available, and
were only slightly affected by interstellar reddening. There proved to be
a fairly tight correlation between B-V and V-[12] for that color regime in
which B-V is correlated with temperature (i.e., all but the M spectral
class stars). Figure 3 from WCA is reproduced here as Figure 1. From
Table 1 of WCA, it can be calculated that the rms scatter about the mean
relationship is about 0.13 mag for 0.2 < (B-V)0 < 1.6. A similar plot,
but with more scatter and a less tightly correlated relationship, can be
made for spectral type vs. V-[12] color.
Thus, for unreddened stars with available photometry, one can predict
the 12 micron flux. If it deviates from observation by significantly more
than the rms scatter around the mean relationship (~ 0.13 mag), the
association of the star with the IRAS point source must be viewed
suspiciously (or the star has an IR excess/deficit and is very interesting if
the identification can be confirmed by other means).
If one uses the spectral type to predict the V-[12] color, the acceptable
error would be larger, because there is an intrinsic spread in B-V color
within a given spectral class. WCA found that this spread is typically 0.1
mag for stars later than spectral type G. Given that the slope of the
V-[12] vs. B-V relationship is about 1.75, this intrinsic spread would
imply an additional error of 0.2 mag in estimating V-[12]. Added in
quadrature, this would increase the expected error in the prediction
from 0.13 mag to 0.24 mag.
A very serious problem encountered in predicting the V-[12] color is
interstellar reddening. The difficulty is not so serious when a color is
used to predict V-[12], because the effect of reddening is to move the
star along a reddening line that is somewhat parallel to the relationship.
A B-V color excess of 0.1 mag causes a V-[12] excess of 0.31 mag, but the
error in estimating V-[12] is only about 0.14 mag. If the R-I color is used
in place of B-V, the error is reduced to 0.05 mag or 0.11 mag, depending
on the R-I value. But if the spectral type is used in place of B-V as a
temperature indicator, the error is the entire amount of the V-[12]
excess, 0.31 mag, because only the V-[12] value is changed by the
reddening. In other words, the displacement in Figure 1 would be
vertical if spectral type is used instead of an observed color.
Various spectral type and photometric catalogs were obtained from the
CDROM. Spectral types were obtained from three different catalogs.
The Henry Draper catalog (Cannon & Pickering 1918-24; Cannon
1925-36) has spectral types for nearly 28,000 of the stars in the PSC,
more than 85%. However the HD catalog has no luminosity class
information, and the M spectral types do not have subclasses equivalent
to the MK system. The MHD catalog (Houk & Cowley 1975; Houk
1978; Houk 1982; Houk & Smith-Moore 1988) has the most complete
spectroscopic data, but covers only the sky south of -12 degrees
declination. The MK Extension catalog (Morris-Kennedy 1983) contains
very few of the stars in the PSC. The most extensive photometric catalog
is that of Mermilliod (1991), which has entries for about 8500 stars. The
combined catalog of Lanz (1986) was also included, but contains data for
only about 1600 stars. The catalog of Morel and Magnenat (1978) was
used as the primary source of the color R-I on the Johnson system.
For those stars with known color and spectral class the intrinsic color
was obtained from FitzGerald (1970). Comparing the intrinsic color to
the observed color yielded the color excess directly. The effect of
reddening was then removed from the estimation of V-[12]. The error
resulting from removal of the reddening is equal to the spread in color
with spectral type, so that the overall error is 0.24 mag. To confirm an
IRAS source as a particular star, it was required that the residual
calculated-observed V-[12] color be within 0.5 mag, or almost exactly 2
sigma.
For stars with only a spectral type, the problem was approached in a
different manner. The intrinsic color determined from the spectral type
was used to calculate a value of V-[12]. The B-V color excess was
determined using the empirical relationship of Arenou, Grenon, and
Gomez (1992). This relationship estimates the visual absorption from
the galactic coordinates and the distance. If a luminosity class was
available, the absolute magnitude was determined from the spectral type
using the empirical relationships of Schmidt-Kaler (1982), and distance
determined from the difference between the apparent and absolute
magnitude (this was calculated in an iterative manner, with the
absorption used to correct the distance estimate). If no luminosity data
were available, the star was assumed to be a dwarf (class V) if earlier
than G5; otherwise the star was assumed to be a giant (class III),
consistent with the treatment of Arenou, Grenon, and Gomez (1992). It
should also be noted that while this scheme is much too smooth to match
the rather clumpy extinction within a few degrees of the galactic plane,
only a small fraction of the sources are in that region. The value of the
color excess E(B-V) calculated this way was used to correct the
estimation of V-[12].
For those stars with only an observed color, the reddening was again
estimated in the same manner, but the technique was more complicated
in practice because the intrinsic color, absolute magnitude, and distance
had to be recalculated in every iteration as they depend on the
reddening. Again the luminosity was assumed to be class III or V. A
color excess was calculated for both classes, and the value that gave the
best match between the observed and predicted V-[12] was adopted.
As lack of a good reddening estimate can be expected to increase the
error, it was decided to adopt a maximum acceptable difference between
the observed and calculated V-[12] of 0.75 mag when only color or
spectral type data are available. When using the spectral type to estimate
V-[12], this limit corresponds to E(B-V) = 0.75/3.1 = 0.24 mag (that is,
an error in color excess of 0.24 mag would produce an error in V-[12] of
0.75 mag). When B-V color is used, E(B-V) = 0.75/1.4 = 0.54 mag
corresponds to the limit. Use of the R-I color on the Johnson system
yields E(B-V) = 0.75/0.55 = 1.4 mag (R-I<0.72) or 0.75/1.1 = 0.68
(R-I>0.72).
4. DISCUSSION
The numbers of stars with each type of data available, and the numbers
of color or questionable identifications, are given in Table 2. For a
normal distribution one would expect to find 95% of the residuals within
2 sigma. For those stars with photometric colors and spectral type data
that permit accurate determination of the reddening, 91% are
confirmed. This suggests that almost all of these stars do match the
IRAS sources. For stars with only photometric or only spectral type
data, the percentages of confirmed matches are somewhat lower. This is
partially explained in terms of the cruder estimate of the reddening. In
addition, V magnitudes for stars without an observed color have been
determined photographically, and are much less accurate than
photometric magnitudes.
There is a striking difference in confirmation rates between those stars
with an MK spectral type (from either the MK Extension catalog or the
MHD catalog) but no observed color and those stars with an HD
spectral type but no observed color. Spectral types from the MK
Extension catalog and the MHD catalog are two-dimensional (i.e. have
luminosity class data), while the HD catalog provides only
one-dimensional spectral types. To determine if the luminosity data
might be the reason for the difference in confirmation rates, the analysis
was repeated using the MK spectral types, but the luminosity class data
were ignored; instead the luminosity class was assumed in the same
manner as for the HD spectral types. The confirmation rates were
unchanged, which implies that the MK Extension and MHD catalogs are
superior for this purpose regardless of the luminosity data. On the other
hand, for those stars with both an observed color and a spectral type, the
confirmation rates seem practically independent of the spectral type
source catalog used.
In an effort to better understand this dependence of confirmation rate
on the spectral types catalog, the data in Table 2 were broken down by
spectral type, with the results given in Table 3. The confirmation rates
are nearly identical when an observed color is available regardless of the
spectral type source catalog, except for the M stars. For stars without an
observed color, the rates are very different for stars of spectral type F or
later. Thus it seems that the spectral types in all the catalogs are
consistent for those stars with an observed color, but not for the redder
stars without an observed color.
The stars with an observed color and spectral type are different from
those with a spectral type but without a color in that the former group is
brighter overall. Stars with an observed color have a median visual
magnitude of 6.32, with only 31% fainter than 7.0. Those stars without
an observed color but with an observed MK spectral type have a median
visual magnitude of 7.91, and 88% are fainter than visual magnitude 7.0.
Stars with only an HD spectral type are fainter still, with a median visual
magnitude of 8.37, and 94% are fainter than 7.0. Because there is little
difference in confirmation rates for the brighter stars (those with an
observed color), it is tempting to state that the HD spectral types are
poor for fainter stars in general. However, because this sample consists
of stars with an IRAS 12-micron magnitude brighter than 5.0, a star with
V fainter than 7.0 must have V-[12] color redder than 2.0 and is thus
spectral type G3 or later. So the difference in confirmation rates
suggests that the HD spectral types differ systematically from the MK
spectral types for the reddest stars, particularly visually faint stars
redder than the Sun.
It can be seen in Table 3 that the confirmation rates vary with spectral
type even for those stars with an observed color and an observed spectral
type. Large percentages of stars with V-[12] excesses for spectral types
B, A, and M have been observed previously. Considering only those
stars in Table 3 with an observed color and spectral type, the percentages
of stars with a V-[12] excess greater than 0.5 mag (i.e., not confirmed) is
given in Table 4, along with the equivalent percentage found by WCA.
The results are very similar. Patten and Willson (1991) considered only
stars of types B, A, and F; while the percentages with an excess were not
broken down by spectral type, it was shown that an excess is correlated
with rapid rotational velocity, which is known to be more common for
stars of spectral type earlier than F. Iyengar and Rengarajan (1991)
analyzed stars of type A to M in the Catalogue of Nearby Stars of Gliese
(1969). Excesses greater than 0.3 mag were found to occur for more
than 5% of the stars in class A and possibly M, but less than 5% of F, G,
and K stars had such an excess.
Thus it seems that 12-micron excesses greater than 0.5 magnitude are
not unusual for stars of spectral types O, B, A, and M. Those star
identifications from the PSC that are not confirmed may not be due to
misidentifications, but rather due to excess flux at 12 microns. For this
reason, no source has been excluded from the catalog because of the
results of the color confirmation. Rather, the residual (calculated -
observed) value of V-[12] has been included in the catalog for
consideration by the user. Those sources considered questionable are
flagged, as are those without sufficient data for analysis. Certainly
source identifications that are confirmed should be regarded as more
reliable.
5. K MAGNITUDES
The technique of WCA to predict the V-[12] color can of course be used
to predict other colors involving IRAS magnitudes if sufficient
observational data exist. For example, Odenwald (1991) suggested that
the Johnson system K filter (2.2 micron) magnitudes should be very
similar to the IRAS 12-micron magnitudes. Using those stars with both
an observed K magnitude and an IRAS 12-micron flux, the relationship
between K-[12] and (B-V)0 can be determined and then used to predict
the K magnitudes. The catalog of Morel and Magnenat (1978) contains
K magnitudes for 425 stars that have IRAS identifications confirmed by
color and 87 stars that do not have confirmed identifications. A
two-color plot of these data is shown in Figure 2. As Odenwald
predicted, the K magnitudes and 12-micron magnitudes are nearly
identical, with the (K-[12])0 color showing only a small trend with
(B-V)0. A line was fitted to all the data, then a new fit was derived after
deleting all data more than 0.4 mag from the previous line. This
iterative approach is very similar to the treatment of WCA. The final
result was
(K-[12])0 = 0.012 + 0.104*(B-V)0, (B-V)0 < 1.6
~ .006 ~ .006
For the 474 points included in the fit (all but 3 of the confirmed stars,
plus 52 of the unconfirmed stars), the rms deviation from the line is
0.087 mag.
Because this fitted line is very insensitive to (B-V)0, it is fairly insensitive
to errors in (B-V) or to reddening. The color excess E(K-[12]) is
assumed to be 0.4*E(B-V), and should be due entirely to absorption in
the K filter. The small errors in slope and intercept yield errors in the
(K-[12])0 color small relative to the error in the 12-micron magnitude,
which is assumed to be 0.10 mag (see Table VII.D.2 of the Explanatory
Supplement). Thus the error in the K0 magnitude, derived by adding
[12] to (K-[12])0, can be taken to be 0.10 also. If the error in E(B-V) is
assumed to be 0.1 mag (due mostly to variation in intrinsic color for a
particular spectral type), then the error in the reddened K magnitude K
= K0 + 0.4*E(B-V) is about 0.11 mag.
If the (K-[12])0 excess were due to excess flux in the 12-micron filter
only, then predicting the (V-K)0 color and determining the K magnitude
from that color would be a viable option for those stars whose IRAS
identifications were not confirmed by the V-[12] color. For the same
sample of 512 stars used previously a two-color plot is shown in Figure 3.
Many of the stars whose IRAS identifications cannot be confirmed by
color also show unusual (V-K)0 values. One obvious explanation is that
both the K and the 12-micron fluxes are larger than expected. Also
noteworthy is the extreme sensitivity of V-K to reddening, with E(V-K)
= 2.7*E(B-V), but there would have to be huge errors in E(B-V) to
account for the V-K excesses seen in Figure 3. Such errors might arise if
there were an identification error in the spectral type catalog, for
example. It is possible that the absorption as a function of wavelength is
atypical, so that the reddening corrections are inappropriate.
Multiplicity involving a faint red companion is certainly possible for the
bluer stars. Further work, possibly including K magnitude observations,
may be needed to explain this correlation of excesses in the K and
12-micron magnitudes. The important fact for this work is that there
seems to be no advantage in using the (V-K)0 color to estimate the K
magnitudes for stars without confirmed identifications.
6. THE CATALOG
The catalog contains an identifier from one of the Durchmusterung
catalogs as well as the IRAS PSC identification. The right ascension,
declination, and proper motions are given on both the FK5 (J2000.0)
system and the FK4 (B1950.0) system. There is a flag to indicate which
of the astrometric catalogs is the source of the position. Besides the
IRAS fluxes for each of the bands, the V magnitude is given along with
an indicator of the source of the V magnitude value. A spectral type and
source is given, along with an estimate of the B-V color excess and a flag
to indicate the method by which the excess was determined.
The types of data used for color confirmation of PSC identifications are
also indicated. The (calculated - observed) V-[12] is given in
magnitudes, and a flag indicates whether this deviation is within the
acceptable limits (which are based on the types of data used). If there
are not sufficient data to attempt color confirmation, there is an
indication as to what data are lacking. Predicted K magnitudes are given
for those stars whose identifications are considered to be confirmed.
Finally the catalog contains several useful quantities from the IRAS PSC
catalog, such as the flux quality indicator, the point source correlation
coefficient, and an estimate of the probability of variability as
determined from the IRAS data. These are more fully described in the
IRAS Explanatory Supplement.
RBH wishes to thank Sten Odenwald, Tom Corbin, and Gart
Westerhout for helpful comments, Sean Urban and Geoff Douglass for
help obtaining data, and Stephen Gauss for assistance in arranging the
layout of this paper and distribution of the catalog. Also the help and
patience of Brenda Corbin and Greg Shelton of the USNO library is
greatly appreciated. The conception of and groundwork for this project
was done exclusively by Dr. Robert S. Harrington, whose untimely death
in January 1993 at age 50 is still mourned by his staff.
REFERENCES
Arenou, F., Grenon, M., and Gomez, A. 1992, Astron. & Astrophys., 258,
104
Cannon, A.J. 1925-36, "The Henry Draper Extension", Ann. Astron.
Obs. Harvard College, 100
Cannon, A.J., & Pickering, E.C. 1918-24, "The Henry Draper Catalog",
Ann. Astron. Obs. Harvard College, 91-99
Cannon, A.J. 1925-36, "The Henry Draper Extension", Ann. Astron.
Obs. Harvard College, 100
Corbin, T.E. 1978, in IAU Colloquium No. 48, "Modern Astrometry",
edited by F.V. Prochazka and R.H. Tucker, (University Observatory,
Vienna), p.505
Corbin, T.E., & Urban, S.E. 1990, in IAU Symposium No. 141, "Inertial
Coordinate System on the Sky", edited by J.H. Lieske and V.K.
Abalakin, (Kluwer,Dordrecht), p.433
FitzGerald, M.P. 1970, A&A, 4, 234
Fricke, W., et. al. 1988, Fifth Fundamental Catalogue (FK5) Part I: The
Basic Fundamental Stars, Veroeff. Astron., Rechen-Institute
Heidelberg, No. 32
Fricke, W., Schwan, H., & Corbin, T.E. 1991, Fifth Fundamental
Catalogue (FK5) Part II: The FK5 Extension- New Fundamental Stars,
Veroeff. Astron., Rechen-Institute Heidelberg, No. 33
Hoffleit, D., & Jaschek, C. 1982, The Bright Star Catalogue, Yale
University Observatory, New Haven, USA
Houk, N. 1978, University of Michigan Catalogue of Two-Dimensional
Spectral Types for the HD Stars, vol. 2, University of Michigan
Houk, N. 1982, University of Michigan Catalogue of Two-Dimensional
Spectral Types for the HD Stars, vol. 3, University of Michigan
Houk, N., & Cowley, A.P. 1975, University of Michigan Catalogue of
Two-Dimensional Spectral Types for the HD Stars, vol. 1, University of
Michigan
Houk, N., & Smith-Moore, M. 1988, University of Michigan Catalogue
of Two-Dimensional Spectral Types for the HD Stars, vol. 4, University
of Michigan
IRAS Catalogues and Atlases: The Explanatory Supplement 1987, edited
by C.A. Bechman, G. Neugebauer, H.J. Habing, P.E. Clegg, T.J. Chester,
NASA RP-1190, vol. 1
IRAS Catalogues and Atlases: The Point Source Catalog 1987, edited by
C.A. Bechman, G. Neugebauer, H.J. Habing, P.E. Clegg, T.J. Chester,
NASA RP-1190, vol. 2-6
Iyengar, K.V.K., and Rengarajan, T.N. 1991, Astron. Astrophys., 250, 420
Lanz, T. 1986, A&A Suppl., 65, 195 (from CDROM)
Mermilliod, J.-C. 1991, unpublished (from CDROM)
Morel, M., & Magnenat, P. 1978, Astron. Astrophys. Suppl, 34, 477
Morris-Kennedy, P. 1983, unpublished (from CDROM)
Odenwald, S. 1991 (private communication)
Patten, B.M., & Willson, L. A. 1991, A.J., 102, 323
Roman, N.G. 1993 (private communication)
Roman, N.G., Warren, W.H., and Schofield, N.J. 1991, unpublished
(from CDROM)
Schmidt-Kaler, T. 1982, Landolt-Bornstein, Neue Ser., Gruppe VI, 2b, 14
Selected Astronomical Catalogs, vol. 1, No. 1 (USA_NASA_ADC_CAT_0011),
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Worley, C.E., and Douglass, G.G. 1984, unpublished (from CDROM).
Table 1:
Catalog Number %
=======================================
FK5 1352 4
FK5 Extension 1229 4
IRS 8110 24
ACRS 22987 68
=====================================
Total 33678
Table 2
Confirmation Number Color Number
Data Available Criterion Total Confirmed Questionable
-----------------------------------------------------------------------
Color and MK within
Spectral Type 0.5 mag 3408 3140 = 92 % 268 = 8%
Color and HD within
Spectral Type 0.5 mag 3564 3206 = 90 % 358 = 10%
MK Spectral within
Type Only 0.75 mag 8571 7374 = 86 % 1197 = 14%
HD Spectral within
Type Only 0.75 mag 10234 4647 = 45 % 5587 = 55%
Color Only within
0.75 mag 202 158 = 78 % 44 = 22%
------------------------------------------------------------------------
Total with Data 25979 18525 = 71 % 7454 = 29%
No Data Available 7699 0 = 0 % 7699 = 100%
Total 33678 18525 = 55 % 15153 = 45%
Table 3
Data Available O B A F G K M
-----------------------------------------------------------------------
Color and MK
Spectral Type
% confirmed 0 75 93 97 99 98 50
Total number 2 195 209 434 648 1618 302
Color and HD
Spectral Type
% confirmed - 67 92 95 97 97 40
Total number 0 92 214 254 450 2199 355
MK Spectral
Type Only
% confirmed - 37 62 78 84 91 72
Total number 0 37 53 147 854 5985 1495
HD Spectral
Type Only
% confirmed - 31 35 64 52 47 19
Total number 0 35 57 120 997 8079 946
=======================================================================
Table 4
Source B A F G K M
-----------------------------------------------------------------------
This work(a) 28 7 4 3 4 56
WCA (1987) 40 13 5 3 1 29
Notes to Table 4
(a) includes all data with an observed color and spectra type