The ESA Hipparcos satellite made measurements of over 12,000 double stars and discovered 3406 new systems. In addition to these, 4706 entries in the Hipparcos Catalogue correspond to double star solutions that did not provide the classical parameters of separation and position angle ({rho}, {theta}) but were the so-called problem stars, flagged "G," "O," "V," or "X" (field H59 of the main catalog). An additional subset of 6981 entries were treated as single objects but classified by Hipparcos as "suspected nonsingle" (flag "S" in field H61), thus yielding a total of 11,687 "problem stars." Of the many ground-based techniques for the study of double stars, probably the one with the greatest potential for exploration of these new and problem Hipparcos binaries is speckle interferometry. Results are presented from an inspection of 848 new and problem Hipparcos binaries, using both archival and new speckle observations obtained with the USNO and CHARA speckle cameras.
We have detected the tip of the red giant branch (TRGB) in the solar neighborhood using near-infrared photometry from the Two Micron All Sky Survey (II/246) and DIRBE (J/ApJS/154/673) catalogs, and revised Hipparcos parallaxes. We confirm that the revised Hipparcos parallaxes are superior to the original ones, and that this improvement is necessary to detect the TRGB. We find a tip absolute magnitude of M_K_=-6.85+/-0.03, in agreement with that expected from previous tip measurements of the Large Magellanic Cloud, Small Magellanic Cloud, and Bulge. This represents the first geometric calibration of the TRGB and extends previous calibrations, based on metal-poor globular clusters, to solar metallicities. We attempted to use the TRGB to confirm the presence of the Lutz-Kelker bias, with inconclusive results. Attempts to detect the tip in the I band also produced inconsistent results, due to a lack of precise, homogeneous photometry for these bright stars.
We present a cross-calibration of Hipparcos and Gaia EDR3 intended to identify astrometrically accelerating stars and to fit orbits to stars with faint, massive companions. The resulting catalog, the EDR3 edition of the Hipparcos-Gaia Catalog of Accelerations (HGCA), provides three proper motions with calibrated uncertainties on the EDR3 reference frame: the Hipparcos proper motion, the Gaia EDR3 proper motion, and the long-term proper motion given by the difference in position between Hipparcos and Gaia EDR3. Our approach is similar to that for the Gaia DR2 edition of the HGCA but offers a factor of ~3 improvement in precision thanks to the longer time baseline and improved data processing of Gaia EDR3. We again find that a 60/40 mixture of the two Hipparcos reductions outperforms either reduction individually, and we find strong evidence for locally variable frame rotations between all pairs of proper motion measurements. The substantial global frame rotation seen in DR2 proper motions has been removed in EDR3. We also correct for color- and magnitude-dependent frame rotations at a level of up to ~50{mu}as/yr in Gaia EDR3. We calibrate the Gaia EDR3 uncertainties using a sample of radial velocity standard stars without binary companions; we find an error inflation factor (a ratio of total to formal uncertainty) of 1.37. This is substantially lower than the position-dependent factor of ~1.7 found for Gaia DR2 and reflects the improved data processing in EDR3. While the catalog should be used with caution, its proper motion residuals provide a powerful tool to measure the masses and orbits of faint, massive companions to nearby stars.
This database table contains the Hipparcos Input Main Cataloge of 118209 stars. The Hipparcos Input Catalogue was constructed as the observing program for the European Space Agency's Hipparcos astrometry mission. The requirements of the project in terms of completeness, sky coverage, astrometric and photometric accuracy, as well as the necessary optimization of the scientific impact, resulted in an extended effort to compile and homogenize existing data, to clarify sources and identifications, and, where needed, to collect new data matching the required accuracy. This has resulted in an unprecedented catalog of stellar data including up-to-date information of positions, proper motions, magnitudes and colors, and (wherever available) spectral types, radial velocities, multiplicity and variability information. The catalog is complete to well-defined magnitude limits and includes a substantial sampling of the most important stellar categories present in the solar neighborhood beyond these limits. The magnitudes vary from 7.3 to 9 mag as a function of galactic latitude and spectral type, and there are no stars fainter than about V=13 mag. The 118209 stars of the Hipparcos Input Catalogue were selected from some 214000 distinct candidates contained in some 214 observations programs. This is a service provided by NASA HEASARC .
The Hipparcos Input Catalogue was constructed as the observing program for ESA's Hipparcos astrometry mission. This has resulted in a catalogue of stellar data including up-to-date information on positions, proper motions, magnitudes, colors, and when available, spectral types, radial velocities, multiplicity and variability information. The catalogue is complete to well-defined magnitude limits, and includes a substantial sampling of the most important stellar categories present in the solar neighbourhood beyond these limits. The magnitude limits vary from 7.3 to 9 magnitudes as a function of galactic latitude and spectral type, and there are no stars fainter than about V = 13 mag. 118000 stars are included in the Hipparcos Input Catalogue, about half of them have been selected within well-defined limits in V magnitude, spectral type and galactic latitude (the "survey"), half of them within proposed observing programs. The mean accuracies achieved, as demonstrated by comparison with the Hipparcos results (Turon et al. 1995A&A...304...82T) are 0.3 arcsec for the positions and 0.25 mag for the Hp magnitude, with accuracies of 0.02 mag or better for more than a third of the catalogue. The data set consists of the main catalogue, and the first supplement which contains more detailed information for multiple system components. Other supplements with identification charts can be found in the published version. A complete description is provided, either as a LaTeX file (intro.tex), or as a plain ascii file (intro.cat).
The Hipparcos and Tycho Catalogues are the primary products of the European Space Agency's astrometric mission, Hipparcos. The satellite, which operated for four years, returned high quality scientific data from November 1989 to March 1993. Each of the catalogues contains a large quantity of very high quality astrometric and photometric data. In addition there are associated annexes featuring variability and double/multiple star data, and solar system astrometric and photometric measurements. In the case of the Hipparcos Catalogue, the principal parts are provided in both printed and machine-readable form (on CDROM). In the case of the Tycho Catalogue, results are provided in machine-readable form only (on CDROM). Although in general only the final reduced and calibrated astrometric and photometric data are provided, some auxiliary files containing results from intermediate stages of the data processing, of relevance for the more-specialised user, have also been retained for publication. (Some, but not all, data files are available from the Centre de Donnees astronomiques de Strasbourg.) The global data analysis tasks, proceeding from nearly 1000 Gbit of raw satellite data to the final catalogues, was a lengthy and complex process, and was undertaken by the NDAC and FAST Consortia, together responsible for the production of the Hipparcos Catalogue, and the Tycho Consortium, responsible for the production of the Tycho Catalogue. A fourth scientific consortium, the INCA Consortium, was responsible for the construction of the Hipparcos observing programme, compiling the best-available data for the selected stars before launch into the Hipparcos Input Catalogue. The production of the Hipparcos and Tycho Catalogues marks the formal end of the involvement in the mission by the European Space Agency and the four scientific consortia. For much more information about this catalog, such as fuller descriptions of the parameters, the user is urged to check the Hipparcos and Tycho Catalogs website at <a href="https://www.cosmos.esa.int/web/hipparcos/catalogues">https://www.cosmos.esa.int/web/hipparcos/catalogues</a>. This database table was created by the HEASARC in April 2000 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/I/239">CDS Catalog I/239</a> file hip_main.dat.gz, the Hipparcos Main Catalog. It was updated in October 2002 to fix some entries which were missing coordinates. This is a service provided by NASA HEASARC .
A new reduction of the astrometric data as produced by the Hipparcos mission has been published, claiming accuracies for nearly all stars brighter than Hipparcos magnitude H_p = 8 to be better, by up to a factor 4, than in the original catalog. The new Hipparcos astrometric catalog has been checked for the quality of the data and the consistency of the formal errors as well as the possible presence of error correlations. The differences with the earlier publication of the Hipparcos Catalog are explained in the reference paper. The internal errors are followed through the reduction process, and the external errors are investigated on the basis of a comparison with radio observations of a small selection of stars, and the distribution of negative parallaxes. Error correlation levels are investigated and the reduction by more than a factor 10 as obtained in the new catalog is explained. The formal errors on the parallaxes for the new catalog are confirmed. The presence of a small amount of additional noise, though unlikely, cannot be ruled out. The new reduction of the Hipparcos astrometric data provides an improvement by a factor 2.2 in the total weight compared to the Hipparcos catalog published in 1997, and, according to the author, provides much improved data for a wide range of studies on stellar luminosities and local galactic kinematics. Note that this catalog version is slightly different from the one published in the book, as an error that sometimes affected the goodness of fit value for the solution was corrected. The first version of these data archived at the CDS (between June and 15 September 2008) also contained errors which were corrected after this date. This table was created by the HEASARC in August 2009 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/I/311">CDS Catalog I/311</a> file hip2.dat, "the Astrometric Catalogue". This is a service provided by NASA HEASARC .
We compare the absolute visual magnitude of the majority of bright O stars in the sky as predicted from their spectral type with the absolute magnitude calculated from their apparent magnitude and the Hipparcos parallax. We find that many stars appear to be much fainter than expected, up to five magnitudes. We find no evidence for a correlation between magnitude differences and the stellar rotational velocity as suggested for OB stars by Lamers et al. (1997A&A...325L..25L), whose small sample of stars is partly included in ours.
The Hipparcos photometry of the chemically peculiar main-sequence B, A and F stars are examined for variability. Some non-magnetic CP stars, Mercury-Manganese and metallic-line stars, which according to canonical wisdom should not be variable, may be variable and are identified for further study. Some potentially important magnetic CP stars are noted.
For Hipparcos M, S, and C spectral type stars, we provide calibrated instantaneous (epoch) Cousins V-I color indices using newly derived HpV_T2_ photometry. Three new sets of ground-based Cousins VI data have been obtained for more than 170 carbon and red M giants, observed at SAAO in 1984 and 1987 (table1), at Siding Spring Observatory in 2002 (table2), and with the Automatic Photoelectric Telescopes located at Fairborn Observatory from 1996 (table3). These datasets in combination with the published sources of VI photometry served to obtain the calibration curves linking Hipparcos/Tycho Hp-V_T2_ with the Cousins V-I index. In total, 321 carbon stars and 4464 M- and S-type stars have new V-I indices. The standard error of the mean V-I is about 0.1mag or better down to Hp~9 although it deteriorates rapidly at fainter magnitudes. These V-I indices can be used to verify the published Hipparcos V-I color indices. Thus, we have identified a handful of new cases where, instead of the real target, a random field star has been observed. A considerable fraction of the DMSA/C and DMSA/V solutions for red stars appear not to be warranted. Most likely such spurious solutions may originate from usage of a heavily biased color in the astrometric processing.