Long-term photometry of the Wolf-Rayet stars WR 137, WR 140, WR 148, and WR 153

Kyril P. Panov, Martin Altmann, Wilhelm Seggewiss

In 1991, a long term UBV-photometry campaign of four Wolf-Rayet stars was started using the 60 cm telescope of the National Astronomical Observatory Rozhen, Bulgaria. Here we repor…