A&A 365, 222-227 (2001)
DOI: 10.1051/0004-6361:20000010
G. A. Gontcharov1 - A. A. Andronova1 - O. A. Titov2 - E. V. Kornilov1
Send offprint request: G. A. Gontcharov
1 - Pulkovo Observatory, Saint-Petersburg 196140, Russia
2 -
Astronomical Institute, Saint-Petersburg State University,
Saint-Petersburg, Russia
Received 26 April 2000 / Accepted 28 September 2000
Abstract
A direct combination of the positions given in the HIPPARCOS catalogue
with astrometric ground-based catalogues having epochs later than 1939
allows us to obtain new proper motions for the 1535 stars of the Basic
FK5. The results are presented as the catalogue Proper Motions of
Fundamental Stars (PMFS), Part I. The median precision of the proper
motions is 0.5 mas/year for
and 0.7 mas/year
for
.
The non-linear motions of the photocentres of a
few hundred astrometric binaries are separated into their linear and
elliptic motions. Since the PMFS proper motions do not include the
information given by the proper motions from other catalogues
(HIPPARCOS, FK5, FK6, etc.) this catalogue can be used as an
independent source of the proper motions of the fundamental
stars.
Key words: astrometry - reference systems - catalogs
Author for correspondance: olegtitov@mail.ru
The proper motions in the HIPPARCOS catalogue (hereafter HIP) (ESA 1997) can be improved by combining the HIP and ground-based data. The reasons why this should be done are well-known. They are discussed, for example, in the description of recently realized FK6 catalogue, Part I, by Wielen et al. (1999). The FK6 is a combination of the HIP with FK5 (Fricke et al. 1988; Fricke et al. 1991). Part I contains 878 stars from the FK5 catalogue with little or no indication of duplicity. The FK6 shows non-linear motions of some of the stars, but it cannot provide details of such motions because the ground-based data are represented by the compilation catalogue FK5.
To investigate the proper motions with emphasis on non-linear motions of stars the direct combinations of the HIP with ground-based catalogues were proposed by Gontcharov & Kornilov (1997) as well as by Wielen et al. (1999) (see p. 6, 7) in their project "FK7''. In the process the systematic errors in each ground-based catalogue have to be eliminated individually reducing of each catalogue to the HIPPARCOS system.
An advantage of this approach is that one can use the same procedure both for single and non-single, linearly and non-linearly moving stars. Therefore, proper motions of thousands of stars can be improved simultaneously. It would be reasonable to begin with 4638 stars common to the HIP and FK5 because they have been the most extensively observed from the ground. The Proper Motions of Fundamental Stars (PMFS) catalogue, Part I - 1535 stars from the Basic FK5 - is the result of our direct combination of the HIP with over 60 compiled and observational ground-based catalogues. The proper motions of the stars from the FK5 Extension will be considered in Part II of the PMFS.
To trace the non-linear motions of the stars one should use the most
precise observational catalogues with a spread in epoch, especially
earlier ones. The catalogues should be evenly and closely (ideally
annually) distributed over the time interval. Moreover, for correct
estimation of the systematic errors every catalogue should contain
reasonable number of stars and cover a rather wide interval of
and
.
For the last reason we rejected several zonal
catalogues, some obtained with astrolabes and some others.
We have analyzed a hundred observational catalogues as described in
Gontcharov & Andronova (1997),
Andronova (1998) and Gontcharov et al.
(1998). Hereafter we reject the observations made at
zenith distances
as not being accurate enough. For the
evaluation of the catalogues the mean absolute values of the
differences
and
in the sense
"observational catalogue minus HIP at the observational catalogue
epoch'' were calculated twice for every catalogue: before and after the
elimination of systematic errors as described in the section "Method''.
The procedure for the determination of the systematic errors was much
less effective for older catalogues probably because of the
degradation of the HIP positions at earlier epochs. In other words,
the method of direct combination of the HIP with ground-based
catalogues seems to be acceptable only for those catalogues with
epochs at which the HIP (as the reference) is still several times more
precise. It turns out that most catalogues observed after 1940 (as
against a few observed before 1940) have mean absolute values of
coordinate differences "catalogue minus HIP'' <150 mas after
elimination of systematic errors.
In order to get a uniform and dense set of observational catalogues, we decided to reject all catalogues observed before 1939 as well as those with mean absolute value of coordinate differences "catalogue minus HIP'' <150 mas after elimination of systematic errors. The final list of catalogues used for positions includes 57 observational catalogues with epochs between 1939 and 1995 listed in Table 2 (hereafter denoted observational catalogues). It gives, on average, 20 observations per star spread over 40 years. This means that we can investigate the non-linear motions of stars with periods from about 10 to 100 years and amplitudes >100 mas. Apparently, the use of a few accurate catalogues observed before 1939 would add little to the investigation of non-linear motions of bright stars, but they may be appropriate for investigating fainter stars with poor observational histories.
We used the positions and parallaxes from the HIP; radial velocities from the HIPPARCOS input catalogue (HIC) (Turon et al. 1993); the proper motions from the HIP and best ground-based compilations: GC (Boss 1937), N30 (Morgan 1952), FK5, N70E (Kolesnik 1997), CMC9 (Carlsberg Meridian Catalogue # 9 1997), KSV2 (Time Service Catalogue 2) (Gorshkov & Scherbakova 1998); and the positions from the observational catalogues. All mentioned ground-based catalogues were transferred to the equinox J2000.
Since the discrepancies between HIP and ground-based proper motions of non-linearly moving stars may be great (sometimes >50 mas/year), proper motions from the HIP, GC, N30, FK5, N70E, CMC9 and KSV2 were used for the calculation of mean weighted proper motions as initial values for the main procedure. These ground-based compilation catalogues were first adjusted to the HIPPARCOS system: the proper motion differences in the sense "catalogue minus HIP'' were approximated by polynomials, which were then eliminated from the ground-based proper motions. The weights were calculated from an intercomparison of the catalogues by the method described by Zverev et al. (1980). We did not need a more rigorous reduction of these catalogues because these mean proper motions were used only as initial values for the first of three iterations. The proper motions from these catalogues have no influence on the final result.
The main procedure was:
There are many double and multiple stellar systems in the Basic FK5. The stars are divided into 4 classes. 760 stars can be considered as single. They are marked as the class "S''. All the pairs with separation >10 arcsec and >10000 AU are likely to be common proper motion stars or optical pairs. Their bright components are also marked as single stars.
In the case of wide pairs (separation >10 arcsec but <10000 AU, no orbital motion) the fainter component usually does not affect the ground-based or space astrometry of the brighter one. In this case the method used and the obtained proper motions are acceptable. 187 such stars are marked as the class "W''. Closer pairs need some special consideration.
The parameters (resolving power, field of view etc.) of the astrometric telescopes are so different that whereas one of them may resolve a pair and observes the brighter component, another resolves the pair and observes its photocentre, while yet another does not resolve the pair and observes its photocentre. Therefore, any combination of the results of different telescopes (in our study also) may be doubtful for some pairs, mainly with the separation from 1 to 10 arcsec. 35 such stars are marked as class "C''.
Some of the stars have been known as spectroscopic, eclipsing, close visual binaries or even single ones, but in the series of astrometric observations with different epochs they appear as non-linearly moving photocentres of astrometrically unresolved stellar systems with some hidden (i.e. faint) massive components. Such stellar systems are known as astrometric binaries (see ESA 1997). The class "A'' (astrometric binaries) in the PMFS includes 551 stellar systems with 553 brighter components in the Basic FK5 for which the astrometrically observed photocentre moves, or can move, non-linearly with an amplitude >1 mas:
The PMFS catalogue gives the proper motion components
and
in mas/year, their mean
errors and classification of the stellar systems by the type of
duplicity. The PMFS is presented in Table 3 deposited in
machine-readable form at the CDS. The mean error of the proper motion
components varies from 0.3 to 2.0 mas/year. The median precision is
0.5 mas/year for
and 0.7 mas/year for
.
The format of the catalogue is given in Table 1. The stars
are listed in order of HIP number.
Bytes | Format | Units | Explanations |
1-6 | I6 | [122,118322] HIPPARCOS number | |
7-11 | I5 | [1,1670] FK5 number | |
12-19 | F8.1 | mas/year | [-3629.0,4141.8]
![]() |
20-23 | F4.1 | mas/year | [0.4,2.0] Mean error of
![]() |
24-31 | F8.1 | mas/year | [-5811.1,3267.5]
![]() |
32-35 | F4.1 | mas/year | [0.3,2.0] Mean error of
![]() |
36-36 | I1 | blank | |
37-37 | A1 | [ACSW] Class of stellar system |
Abbreviation | Name in CDS | Observatory | Telescope | Reference | Epoch |
W150 | I/100A | Washington | 6-inch transit circle | Watts & Adams (1949) | 1939 |
W250 | I/100A | Washington | 6-inch transit circle | Watts et al. (1952) | 1945 |
W350 | I/100A | Washington | 6-inch transit circle | Adams et al. (1964) | 1953 |
W450 | I/100A | Washington | 6-inch transit circle | Adams et al. (1968) | 1960 |
W550 | I/100A | Washington | 6-inch transit circle | Hughes & Scott (1982) | 1967 |
W1j00 | Washington | 6-inch transit circle | Holdenried & Rafferty (1997) | 1980 | |
WL50 | El Leoncito | 7-inch transit circle | Hughes et al. (1992) | 1971 | |
PU55A | Pulkovo | Tepfer meridian circle | Bedin et al. (1983) | 1955 | |
PU58A | Pulkovo | Pulkovo large transit circle | Nemiro et al. (1977) | 1958 | |
PU58D | Pulkovo | Ertel-Struve vertical circle | Bagildinsky & Kossin (1966) | 1958 | |
PU72D | Pulkovo | Ertel-Struve vertical circle | Bagildinsky et al. (1986) | 1972 | |
SPU66D | Cerro Calan | photographic vertical circle | Naumov (2000) | 1966 | |
PVC96 | I/242 | Pulkovo | photographic vertical circle | Bagildinsky et al. (1998) | 1991 |
SPF1A | I/82 | Cerro Calan | Repsold meridian circle | Anguita et al. (1975) | 1965 |
SPF1DS | J/A+AS/67/1 | Cerro Calan | Repsold meridian circle | Carrasco & Loyola (1987) | 1965 |
SPF1DP | Cerro Calan | Repsold meridian circle | Gnevysheva & Zverev (1983) | 1965 | |
SPF2 | I/44 | Cerro Calan | Repsold meridian circle | Baturina et al. (1986) | 1966 |
SPF3 | I/78 | Cerro Calan | Zeiss transit instrument | Loyola & Shishkina (1974) | 1964 |
Santiago67 | I/89A | Cerro Calan | Repsold meridian circle | Carrasco & Loyola (1981) | 1967 |
SantiagoFC83 | J/A+AS/95/355 | Cerro Calan | Repsold meridian circle | Carrasco & Loyola (1992) | 1983 |
SPU71A | Cerro Calan | Pulkovo large transit circle | Varin et al. (1981) | 1971 | |
Nikolaev60A | Nikolaev | transit circle | Markina & Petrov (1969) | 1960 | |
Nikolaev60D | Nikolaev | vertical circle | Bozhko & Zimmermann (1977) | 1960 | |
Goloseevo81D | Goloseevo | vertical circle | Lazorenko (1985) | 1981 | |
Brorfelde68 | I/30 | Brorfelde | Carlsberg meridian circle | Olsen Fogh et al. (1973) | 1968 |
Brorfelde73 | I/99 | Brorfelde | Carlsberg meridian circle | Helmer & Olsen Fogh (1982) | 1973 |
Brorfelde82 | I/99 | Brorfelde | Carlsberg meridian circle | Helmer et al. (1983, 1984) | 1982 |
CMC1 | I/126 | La Palma | Carlsberg meridian circle | CMC (1989) | 1984 |
CMC2 | I/126 | La Palma | Carlsberg meridian circle | CMC (1989) | 1985 |
CMC3 | I/133 | La Palma | Carlsberg meridian circle | CMC (1989) | 1986 |
CMC4 | I/147 | La Palma | Carlsberg meridian circle | CMC (1989) | 1987 |
CMC5 | I/170A | La Palma | Carlsberg meridian circle | CMC (1991) | 1989 |
CMC6 | I/189 | La Palma | Carlsberg meridian circle | CMC (1992) | 1990 |
CMC7 | I/205 | La Palma | Carlsberg meridian circle | CMC (1993) | 1991 |
CMC8 | I/213 | La Palma | Carlsberg meridian circle | CMC (1994) | 1993 |
CMC9 | La Palma | Carlsberg meridian circle | CMC (1997) | 1994 | |
Perth70 | I/62C | Perth | Hamburg meridian teles. | Høg & von der Heide (1976) | 1970 |
Perth75 | I/97 | Perth | Hamburg meridian teles. | Nikoloff & Høg (1991) | 1975 |
Perth83 | I/168 | Perth | Hamburg meridian teles. | Harwood (1990) | 1984 |
BMC74 | I/63 | Bordeaux | meridian circle | Mazurier et al. (1977) | 1974 |
BMC89 | Bordeaux | meridian circle | Requieme (1993) | 1989 | |
Beograd69D | Beograd | vertical circle | Sadzakov & Saletic (1972) | 1969 | |
Beograd84 | J/A+AS/77/411 | Beograd | meridian circle | Sadzakov & Dacic (1989) | 1984 |
CPASJ2 | J/A+AS/136/1 | San Juan | Beijing astrolabe | Manrique et al. (1999) | 1994 |
PACP4 | I/182 | Beijing | photoelectric astrolabe | Lu Lizhi (1991) | 1987 |
PPCP3 | Beijing | transit instrument | Lu Lizhi (1990) | 1982 | |
PPCP4 | Beijing | transit instrument | Wang & Lu Lizhi (1991) | 1990 | |
QAC2 | J/A+AS/103/427 | Quito | Danjon astrolabe OPL-13 | Kolesnik & Davila (1994) | 1970 |
SAC1 | J/A+AS/18/135 | Cerro Calan | Santiago Danjon astrolabe | Noël et al. (1974) | 1969 |
SAC2 | J/A+AS/106/441 | Cerro Calan | Santiago Danjon astrolabe | Noël (1994) | 1980 |
CERGA92 | J/A+AS/96/477 | CERGA | photoelectric astrolabe | Vigouroux et al. (1992) | 1990 |
Calern99 | J/A+AS/137/269 | Calern | photoelectric astrolabe | Martin et al. (1999) | 1995 |
GCA | J/A+AS/31/159 | various | various astrolabes | Billaud et al. (1978) | 1967 |
KSV (TSC) | various | various | Pavlov (1971) | 1958 | |
KSV2 (TSC2) | various | various | Gorshkov & Scherbakova (1998) | 1982 | |
GCPA | I/180 | various | various astrolabes | GCPA (1992) | 1979 |
GCPA2 | I/181 | various | various astrolabes | Lu Lizhi (1992) | 1987 |
![]() |
Figure 1:
The proper motion differences in mas/year in the sense "FK6
minus HIP'' versus "PMFS minus HIP'' for 878 stars from the FK6, Part I:
![]() ![]() |
Open with DEXTER |
The proper motions of the fundamental stars in the PMFS and FK6 are quite independent. Therefore, it will be very interesting to make a detailed comparison of these catalogues when all parts of the FK6 have been completed. At present we restrict our comparison to the proper motions in HIP, FK6 and PMFS of the 878 stars in Part I of the FK6.
The PMFS proper motions are derived from over 40 years of astrometric observations and can be considered as a "long-term'' prediction of coordinate variations. Therefore, as recommended by Wielen et al. (1999) in Sect. 8 of the FK6, the PMFS proper motions should be compared with the long-term prediction mode of the FK6 (hereafter FK6(LTP)).
The median precision of the FK6(LTP) and PMFS is: 0.46 versus
0.50 mas/year for
and 0.45 versus 0.60 mas/year
for
.
The standard deviation of the differences
"FK6(LTP) minus HIP'' and "PMFS minus HIP'' is: 1.9 versus 2.1 mas/year
for
and 1.9 versus 2.2 mas/year for
.
Thus, formally the PMFS is only about 15% less
accurate than the FK6. One should expect such a situation for these
linearly moving stars because the ground-based data used in the FK5
cover a longer period. However, the inverse error budget may occur for
non-linearly moving stars in the other parts of the FK6.
The standard deviation of the difference "PMFS minus FK6(LTP)'' is
1.3 mas/year for
and 1.5 mas/year for
.
Thus, the PMFS and FK6 are closer to one another than
to the HIP. A strong correlation of the differences "FK6 minus HIP''
and "PMFS minus HIP'' for individual stars is evident from
Fig. 1.
We conclude that, although the accuracy of the PMFS and FK6 seems overestimated, the proper motions in both catalogues compare favourably with the HIP.
Acknowledgements
We thank Dr. Leslie Morrison for improvement of the language and Prof. Roland Wielen for useful discussion.The creators and providers of all mentioned catalogues are gratefully acknowledged. This research has made use of the Centre de Données astronomiques de Strasbourg (CDS), Astronomical Data Center (ADC) at NASA Goddard Space Flight Center and SIMBAD astronomical database.
This work was supported by the Russian foundation for basic research, RFBR, project #97-02-17111.