Indications of a Spatial Variation of the Fine Structure Constant

We previously reported observations of quasar spectra from the Keck telescope suggesting a smaller value of the fine structure constant, alpha, at high redshift. A new sample of 153 measurements from the ESO Very Large Telescope (VLT), probing a different direction in the universe, also depends on redshift, but in the opposite sense, that is, alpha appears on average to be larger in the past. The combined dataset is well represented by a spatial dipole, significant at the 4.1 sigma level, in the direction right ascension 17.3 +/- 0.6 hours, declination -61 +/- 9 degrees. A detailed analysis for systematics, using observations duplicated at both telescopes, reveals none which are likely to emulate this result.