Two new bright X-ray sources in globular clusters, and many less luminous ones in globular clusters and in old open clusters, have been discovered with ROSAT. Accurate positions obtained with ROSAT help identification with optical objects, which however is still very incomplete in globular clusters. One dim globular cluster source has been identified with a recycled radio pulsar; several others may be cataclysmic variables. The four brightest X-ray sources identified in the old open cluster M 67 are puzzling, as we do not understand why they emit X-rays. In comparison with the two old open clusters studied so far, globular clusters are remarkably underluminous in X-rays.
FirstI am grateful to the organizers of this meeting for the opportunity to contribute to this celebration of the 65 th birthday of Joachim Trümper. During my years (1985)(1986)(1987)(1988)(1989) at the Max Planck Institut für extraterrestrische Physik, I have always felt very much at home, as if an 'honorary German', and I thank Joachim and my other colleagues for this. I was impressed with the width and depth of Joachim Trümper's interests, and thoroughly enjoyed my many discussions with him.The deadline for the first Announcement of Opportunity for observing with ROSAT was on a Sunday evening, at midnight (in checking the date, I find it was on my birthday!). Joachim Trümper was in his office that night, to sign proposals until just before the deadline, or almost, as 11 copies needed to be made for submission. Some of the proposals he signed that night contributed to the results discussed in this review.