Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Monitoring of the flow of an ice sheet in Antarctica finds that the surface velocity oscillates by as much as 20 per cent every two weeks: the spring-to-neap tidal cycle seems to be the cause. Although the mechanism through which these tides couple to ice flow has yet to be elucidated, these observations caution against the use of velocity measurements over limited periods to infer long-term changes in flow rate.
Optical observations of γ-ray burst (GRB) 060614 (duration ∼100s) rule out the presence of an associated supernova. This would seem to require a new explosive process: either a massive 'collapsar' that powers a GRB without any associated supernova, or a new type of engine, as long-lived as the collapsar but without a massive star.
GRB 060505 and GRB 060614 were not accompanied by supernova emission down to limits hundreds of times fainter than the archetypal SN 1998bw that accompanied GRB 980425, and fainter than any type Ic supernova ever observed.
Deep optical observations of GRB 060614 show no emerging supernova with absolute magnitude brighter than MV = − 13.7. Any supernova associated with GRB 060614 was therefore at least 100 times fainter, at optical wavelengths, than the other supernovae associated with GRBs.
The bright, nearby γ-ray burst (GRB) 060614 does not fit in either of the two duration classes. Its ∼102-s duration groups it with long-duration GRBs, whereas its temporal lag and peak luminosity fall entirely within the short GRB subclass. This opens the door on a new GRB classification scheme that straddles both long and short bursts.
The observation of the radiative decay mode of free neutrons, with measurements that agree with theoretical predictions may provide opportunities for more detailed investigations of the weak interaction processes involved neutron beta decay.