Ginga observations of Her X-1 in the short high state: evidence for an extended emission region

The short high state in Her X-1 was observed with good coverage and good sensitivity with the Ginga LAC in 1989. These observations have so far not been analysed in any detail. Here are reported the results of analyses of the light curves and spectra from this data set. The spectral model has absorbed and unabsorbed components. The behaviour of these two components during the short high state indicates a spatially extended continuum source. The iron-line intensity is linearly dependent on the total intensity, indicating that the total intensity is reprocessed emission. The equivalent width of ?0.7 keV is consistent with an illuminated disc geometry, with most of the radiation of the central source (the pulsar) blocked from the observer's view. An extended ingress is seen which is a persistent feature during the short high state. The ingress duration gives a source size of ～3×10⁹ cm, corresponding to the inner disc.