The teaching of astronomy in Plato's Republic

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Abstract. We present V magnitudes, (B − V ) and (U − B) colours of close visual double star components, and their differences as well as separations and position angles of 40 visual double stars. The common properties of the members of this sample are the small angular separation ρ, which is less than 7 , and the common spectral type of the primaries, which are of G-type. The observations made with the Bessel U , B and V filters, while the astrometry was performed in the V filter only. For the observations, the CCD camera attached to the Cassegrain focus of the 90 cm Dutch telescope, at La Silla, Chile, had been used. From the analysis of the data we concluded that from the sample of the fourty double stars observed seven proved to be physical pairs, while the rest must have common origin components.

“…A discussion of the calculation of the final accuracy achieved in the angular separation was presented by Nakos et al (1995) and a detailed one by Sinachopoulos & Seggewiss (1990).…”

Section: Astrometric Data Reductionmentioning

confidence: 99%

Section: Astrometric Data Reductionmentioning

confidence: 99%

${UBV}$ absolute CCD photometry and differential astrometry of close visual double stars, with G-type primaries

Nakos

Sinachopoulos

Dessel

1997

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“…Due to a possible rotation of the H37 system with respect to our data, a complete comparison has to include a rotation of the two systems. We have applied a program given by Sinachopoulos (1986), which has been used before for the determination of systematic differences between radio and optical positions (Brosche & Sinachopoulos 1987). A modification of that program was also the base for the calculation of the rotation of the Hipparcos data for all Bonn fields.…”

Section: Absolute Proper Motions For 48 Starsmentioning

confidence: 99%

Absolute proper motions for the calibration of the Hipparcos proper motion system

Geffert

Klemola

Hiesgen

et al. 1997

Abstract. Absolute proper motions of 48 Hipparcos stars in nine fields distributed over the northern hemisphere are presented. The proper motions have been recently used as part of the Bonn program for the extragalactic link of the Hipparcos proper motion system. We describe methods which have led to the absolute proper motions of the major part of the Bonn fields for the link. For six fields the extragalactic calibration was achieved using the bright quasar in the centre of the field. In addition, data of three fields of globular clusters were included. For these fields the link to an extragalactic reference system was performed by stars, whose absolute proper motions with respect to galaxies were determined on plates of the Lick astrograph. In addition, we used for the link in one field plates from the ESO Schmidt telescope in combination with measurements from glass copies of the Palomar Sky Survey. The accuracy of a single proper motion is of the order of 2 to 3 mas/a for each coordinate.

“…In addition, Oblak (1978Oblak ( , 1980Oblak ( , 1989, Olsen (1982), Lindroos (1984Lindroos ( , 1985, and Sinachopoulos (1989Sinachopoulos ( -1991 have also observed many wide visual binaries using the uvby, β system, starting from different motivations.…”

Section: Introductionmentioning

confidence: 99%

UBV photometry of wide visual double stars. V. Double stars with mainly K- and M- type primaries

Sinachopoulos

Dessel

1996

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