 He was instrumental in discovery of the first globular cluster pulsar in 1987 using a supercomputer.With Dale Frail at NRAO and Toshio Murakami and his colleagues at ISAS (predecessor of JAXA that was led by Yasuo Tanaka at that time) Kulkarni showed that soft gamma-ray repeaters are neutron stars associated with supernova remnants.This discovery eventually led to the understanding that neutron stars with extremely high magnetic field called magnetars are the soft gamma-ray repeaters.