... The (1-0) observations were taken in 2004 August/September with the Compact Array at 18.6 GHz. ... This chemistry is well traced by the (1-0) transitions of the HCN and HNC molecules which emit at 88.6 and 90.7 GHz, respectively. ... These observations therefore suggest that the HCN/HNC ratio may be an indicator of massive star formation. [pic] Figure 3: Contours (black) of HCN emission in the starburst galaxy NGC 253 overlaid on an HST/WFPC2 image taken with the F814W filter. ...

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