Temporal X-ray astronomy with a pinhole camera

The first preliminary results from the Ariel-5 All-Sky X-Ray Monitor are presented, along with sufficient experiment details to define the experiment sensitivity. Periodic modulation of the X-ray emission is investigated from three sources with which specific periods have been associated, with the results that the 4.8 h variation from Cyg X-3 is confirmed, a long-term average 5.6 day variation from Cyg X-1 is discovered, and no detectable 0.787 day modulation of Sco X-1 is observed. Consistency of the long-term Sco X-1 emission with a shot-noise model is discussed, wherein the source behavior is shown to be interpretable as 100 flares per day, each with a duration of several hours. A sudden increase in the Cyg X-1 intensity by almost a factor of three on 22 April, 1975 is reported, after 5 months of relative source constancy. The light curve of a bright nova-like transient source in Triangulum is presented, and compared with previously observed transient sources. Preliminary evidence for the existence of X-ray bursts with duration <1 h is offered, with the caveat that there is not yet any supporting evidence to guarantee that the effect is truly astronomical.Paper presented at the COSPAR Symposium on Fast Transients in X- and Gamma-Rays, held at Varna, Bulgaria, 29–31 May, 1975.