X-ray observations of GX 1 + 4 with the monitor proportional counter on board the Einstein Observatory

The results of X-ray observations of GX 1 + 4 with the monitor proportional counter on board the Einstein Observatory (HEAO 2) are presented. Using data from the time interval processor, the value of the approximately 2 minute pulse period at the time of the observations was determined. Previous determinations are discussed, along with evidence for a suggested value of approximately 4 minutes for the pulse period. The phase of first harmonic of the Fourier decomposition of pulse profile is stable within its errors but the phases of higher harmonics are not. The spin-up time scale is determined to be approximately 40 years.