<b>Field 26, 2nd digit</b>: Photoelectric standard stars

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Field 26, 2nd digit: Photoelectric standard stars

Two categories of photoelectric standards are distinguished: [][ C:] the star is a photoelectric standard with confirmed long-term stability (with three or more independent measurements over several years); [ S:] the star is a secondary photoelectric standard star (based on two independent measurements).

[]The photometric accuracies required for a programme star to be considered as a photometric standard range from 0.020 to 0.026 mag (standard error depending on the magnitude, Grenon 1989b). The photoelectric standard stars are used to calibrate the magnitudes derived from the detection chains of the main mission (Hipparcos magnitude, ) and of the Tycho experiment ( and magnitudes), and for monitoring the detector responses (including their colour dependence), the linearity of these responses, and their evolution throughout the mission (Grenon 1985b, 1989b). In the final version of the Hipparcos Input Catalogue, there are 10822 C stars and 3068 S stars.

The Meudon Hipparcos Input Catalogue Team
mer 16 nov 15:51:31 MET 1994