ASKAP Australia Telescope National Facility Antennas Control Systems ASKAP Antenna specification Operating parameters ASKAP ANTENNA SPECIFICATION ­ BASIC OVERVIEW The ASKAP antennas will be · Prime focus (single reflector ) antennas on an az-el mount/drive with a third (polarisation) axis to provide all-sk y coverage (illustrated in Figure 1a) · A The pointing accuracy of the antennas will be 30 arcsec (rms) or better in all operational modes. ...

metrologia The leap second: its history and possible future R. A. Nelson, D. D. McCarthy , S. Malys, J. Levine, B. Guinot, H. F. Fliegel , R. L. Beard and T. R. Bartholome w Abstract. This paper reviews the theoretica l motivatio n for the leap second in the context of the historica l evolutio n of time measurement . Th e periodic insertio n of a leap second step into th e scale of Coordinate d Universal Time (UTC) necessitates frequent changes in comple x timekeepin g systems an d is currentl y th e