DETECTION OF A VERY-LOW HARD X-RAY PULSE FRACTION IN THE BRIGHT STATEOF GX-1+4

We have observed the Galactic center hard X-ray pulsar GX 1+4 on 1993 December 11, in the energy range of 20 - 100 keV with a balloon-borne Xenon filled Multi-cell Proportional Counter (XMPC) telescope. The sou rce was detected in a bright state, the average observed source count rate being 10.1 +/- 0.2 s(-1) per detector. X-ray pulsations with a pe riod of 121.0 +/- 0.4 s were detected in the source at a very high sig nificance level. This, compared with the BATSE observations, gives a s pin down rate of P = 1.6 +/- 1.4 s yr(-1). The pulse fraction in the h ard X-ray range is low (35%), and the observed spectrum is very hard ( power law energy index 0.54 +/- 0.18). The observed source luminosity in the 20 - 100 keV range is 7.9 +/- 0.3 x 10(37) erg s(-1). These pro perties are similar to those seen during the high luminosity spin up s tate of early 1970s and suggest that the source should revert back to a spin-up episode.