Original sentence: These were discovered by Donald Wayne Kurtz using the 20 inch telescope at the South African Astronomical Observatory, who saw 10-20 millimagnitude variations in the lightcurve of the star with a period of 12.15 min
Edited sentence: The oscillations were discovered by Donald Wayne Kurtz using the 20 inch telescope at the South African Astronomical Observatory, who saw 10-20 millimagnitude variations in the lightcurve of the star with a period of 12.15 min