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GRBs 050223 and 050911 are examples of Swift bursts with two of the faintest X-ray afterglows at (relatively) early times. While a faint, fading X-ray afterglow was located for GRB 050223, GRB 050911 was not detected, making any X-ray afterglow extremely faint. The faintness of the afterglow of GRB 050223 could be explained by a large opening or viewing angle, or by the burst being at high redshift. The non-detection of GRB 050911 may indicate the burst occurred in a low-density environment, or, alternatively, was due to a compact object merger, in spite of the apparent long duration of the burst. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

GRBs 050223 and 050911 were discovered by the Swift Burst Alert Telescope (BAT) on 23rd February and 11th September 2005 respectively. The observation of GRB 050223 showed a faint, fading X-ray source, which was identified as the afterglow; GRB 050911, however, was not detected, making any X-ray afterglow extremely faint. The faintness of the afterglow of GRB 050223 could be explained by a large opening or viewing angle, or by the burst being at high redshift. The non-detection of GRB 050911 may indicate the burst occurred in a low-density environment, or, alternatively, was due to a compact object merger, in spite of the apparent long duration of the burst. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In a one-day balloon flight of the Trans-Iron Galactic Element Recorder (TIGER) in 1997, the instrument achieved excellent charge resolution for elements near the Fe peak, permitting a new measurement of the element ratio Co/Ni. The best fit to the data, extrapolated to the top of the atmosphere, gives an upper limit for this ratio of 0.093 ± 0.037 over the energy interval 0.8 to 4.3 GeV/nucleon; because a Co peak is not seen in the data, this result is given as an upper limit. Comparing this upper limit with calculations by Webber & Gupta [14] suggests that at the source of these cosmic rays a substantial amount of the electron-capture isotope [sup 59]Ni survived. This conclusion is in conflict with the clear evidence from ACE/CRIS below 0.5 GeV/nucleon that there is negligible [sup 59]Ni surviving at the source. Possible explanations for this apparent discrepancy are discussed. [ABSTRACT FROM AUTHOR]