The Geneva photometric system

Basic Reference

Golay M. 1972, Vistas in Astron. 14, 13


The multicolour photoelectric system described here has been used at Geneva Observatory since 1963. In the first part are shown he energy distributions for several kinds of stars, obtained from seven hetero-chromatic magnitudes. With this representation it is possible to study the photometric differences produced by a variation in luminosity, spectral type, chemical composition, axial rotation, due to peculiarities, or binarity, or the choice of interstellar absorption law. Later parameters [d], [Delta], [g], B2-V1, obtained by linear combination of colour indices, are introduced. The properties of the parameters are studied and applied to the classification of stars and used to yield some information about chemical composition, axial rotation and interstellar absorption.


The catalogue is a collective work of the Geneva photometric group.

Access to the data and references

Asiago Database on Photometric System (ADPS)

Indices and Parameters

VM, U, V, B1, B2, V1, G

Reddening-free Parameters


 Filter     wavelength       Width
                [Å]           [Å]

   U           3458           170
   B           4248           283
   V           5508           298
   B1          4022           171
   B2          4480           164
   V1          5408           202
   G           5814           206



A few calibrations have been published to determine the effective temperature and log g for the B- and A-type stars.

Relation to indices of other systems

Transformation relations between Geneva colour indices and other systems have been established.

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Last update: 15 January 1999