Value for the gyromagnetic constant

The International Council for Science: Committee on Data for Science and Technology  adopted a new value for the gyromagnetic constant in 2006 (CODATA 2006). The new value is γp′=2.675153362 ⋅ 108 T-1 s-11 (Rev. Mod. Phys. Vol 80, 2008). In order to comply with international standards IAGA adopts the new value to replace the value adopted in 1991 for geomagnetic measurements from 2010 on. Observatories and instrument manufacturers should implement the new value as soon as possible. The difference between the old and new constants, however, amounts to only 15pT in 50,000nT and thus is within the noise level of most of the present day observatory measurements, therefore it can be safely adopted without problem even if immediate implementation by all observatories at the same time cannot be guaranteed.