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Space motions of low-mass stars.
Radial-velocity measures are presented for 225 stars, most of which aredwarf K and M stars. The data were obtained with the CfA digitalspeedometer, whose uncertainty is less than 1 km/s. Calibrations ofthree earlier radial-velocity studies and comparisons with three othercontemporary ones lead to the evaluation of the standard error for anindividual star as determined in each investigation. The data from twomasks, matching solar type and M type stars, form a ratio that measuresstellar surface temperature quite closely and appear to be useful indetecting the presence of unseen companions. A few previouslyunrecognized binaries have been detected; those with most certaintyinclude stars nos. 366B, 453, and 46A of the McCormick lists of dwarfstars.
| Mean positions and proper motions of 224 stars based on PZT observations at Ondrejov in 1973-1986
An improvement of the positions and proper motions for the Ondrejov PZTstar list based on observations of 224 stars in the period 1973-1986 ispresented. The mean epoch of the PZT 86 catalogue is found to be 1981.56with a standard error in right ascension equal to + or - 0.0015 s/ andin delination equal to + or - 0.017 arcsec. The proper motions in rightascension and declination were obtained with an accuracy characterizedby the average standard errors of + or - 0.051 s/cy and + or - 0.57arcsec/cy, respectively. The PZT 86 catalogue is compared with theprevious PZT (1978 and 1983) catalogues, and with the AGK 3 (Dieckvoss,1975) catalogue.
| Mean positions and proper motions of 305 stars obtained from the combination of PZT observations at Ondrejov with AGK positions
Observations of 305 stars carried out at the Ondrejov Observatory in theperiod 1973-1983 were compared to the positions of the same stars in theAGK 2 and AGK 3 catalogs in order to obtain their mean positions andproper motions. The observations were performed in the course of 1140nights using the PZT telescope and comprise more than 32 thousand startransits. The average mean errors in the right ascension and declinationof a star that was observed thoughout the whole period were + or -0.0019 s and + or - 0.019 arcsec in the epoch around 1979. It ispredicted that the errors will increase + or - 0.0055 sec and + or -0.059 arcsec in the year 2000. A table listing the errors in the rightascension and declination is provided.
| Parallaxes and proper motions. XVI
Parallaxes and proper motions are presented for 30 stars, most of whichare dK-M stars in 20 star fields. Seven of the target stars as well asten other stars have no previous parallax determinations. Six of the 20target stars are actually resolved binaries for which both componentswere measured separately; two of the six are not physical pairs. As inthe previous lists in this series, reductions have been made usinglinear plate constants and results are given to the nearestten-thousandth of a second of arc and separately in x and y coordinatesalong with a combined solution. This list is the first in the serieswhich makes full use of the prior selection of parallax stars to achievethe primary goal of the Van Vleck parallax program. This is to determineaccurate physical properties and space motions of a large and unbiasedsample of unevolved nearby stars of the lower main sequence.
| The determination of mean positions and proper motions of 304 stars from PZT observations at Ondrejov
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Osservazione e dati astrometrici
| Costellazione: | Orsa Maggiore |
| Ascensione retta: | 13h52m30.05s |
| Declinazione: | +50°01'06.8" |
| Magnitudine apparente: | 9.787 |
| Moto proprio RA: | 20 |
| Moto proprio Dec: | -3.6 |
| B-T magnitude: | 10.341 |
| V-T magnitude: | 9.833 |
Cataloghi e designazioni:
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