UBV photometry of Be stars at Hvar: 1972–1990^*

¹ Opservatorij Hvar, Geodetski fakultet Sveučilišta u Zagrebu, Kačićeva 26, 10$\,$000 Zagreb, Croatia
² Astronomický ústav Akademie věd České republiky, 251$\,$65 Ondřejov, Czech Republic
³ SK Press, Masarykovo náměstí 35, 251$\,$01 Říčany, Czech Republic
⁴ Odjel za fiziku i biofiziku, Medicinski fakultet Sveučilišta u Zagrebu, Šalata 3, 10$\,$000 Zagreb, Croatia

Send offprint request to: K. Pavlovski

Received: 25 July 1996
Accepted: 19 December 1996

Abstract

A summary of results of the systematic UBV photoelectric monitoring of bright northern Be stars carried out at the Hvar Observatory between 1972 and 1990 is presented. Altogether, 76 Be stars of all luminosity classes were observed and UBV measurements secured. Simultaneously, UBV measurements of 48 check stars (most of them of early spectral types) were obtained. A careful transformation of all observations into the standard Johnson system allowed detection and monitoring of even very mild long-term light and colour variations of these objects. Almost all early-type Be stars in the sample turned out to be variable. For several stars phase-locked light variations related to their binary nature were established. Sudden brightenings, on a time scale of a few days, were detected for o Cas and QR Vul.