Simultaneous observations of energetic (similar to 150 keV) protons upstream of the Earth's bow shock at ACE and WIND

We report measurements of similar to 150 keV proton intensity enhancements obtained at ACE and WIND when both spacecraft were upstream of the Earth's bow shock. We investigate differences in the onset times, the duration's, a nd the local magnetic field orientations for 4 events observed simultaneous ly at the two spacecraft. A simple statistical analysis shows only 2% of th e simultaneous events could be random coincidences, which indicates that ou t of the 20 events observed at each spacecraft, the 4 simultaneous measurem ents are probably observations of the same events. Since these measurements were obtained when the two spacecraft were separated by distances >25 R-E these particles probably originate from a source region that possibly cover s the scale size of the Earth's bow shock (similar to 10 R-E), and this is substantially larger than the smaller source regions proposed by existing m odels.