Information on physical characteristics of astrometric radio sources, magnitude and redshift in the first place, is of great importance for many astronomical studies. However, data usually used in radio astrometry is incomplete and often outdated. Our purpose is to study the optical characteristics of more than 4000 radio sources observed by the astrometric VLBI technique since 1979. Also we studied an effect of the asymmetry in the distribution of the reference radio sources on the correlation matrices between vector spherical harmonics of the first and second degrees. The radio source characteristics were mainly taken from the NASA/IPAC Extragalactic Database (NED). Characteristics of the gravitational lenses were checked with the CfA-Arizona Space Telescope LEns Survey. SIMBAD and HyperLeda databases was also used to clarify the characteristics of some objects. Also we simulated and investigated a list of 4000 radio sources evenly distributed around the celestial sphere. We estimated the correlation matrices between the vector spherical harmonics using the real as well as modelled distribution of the radio sources. A new list of physical characteristics of 3914 astrometric radio sources, including all 717 ICRF-Ext.2 sources has been compiled. Comparison of our data of optical characteristics with the official International Earth Rotation and Reference Systems Service (IERS) list showed significant discrepancies for about half of 667 common sources. Finally, we found that asymmetry in the radio sources distribution between hemispheres could cause significant correlation between the vector spherical harmonics, especially if the case of sparse distribution of the sources with high redshift. We also identified radio sources having many-year observation history and lack redshift. This sources should be urgently observed at large optical telescopes.

Map produced for the Australian Federal Police showing the logged positions of Vessel Immacolata on the 7th October 2007 on a background on AUS808 and AUS809 showing more detail such as the cable protection zone.

Flat model shows all maritime zones excluding coastal waters

This diagram was requested by G Boyes for inclusion into the Fisheries Management (Excepted Areas) Proclamation 2011. Our reference: Job 646

Map compiled on request from AGS Native Title Case QUD6040/2001 Proclamation 3 See 2008/3111 for particulars.

Map compiled on request from AGS Native Title Case QUD6040/2001 Proclamation 4 See 2008/3111 for particulars.

Map compiled on request from AGS Native Title Case QUD6040/2001 Proclamation 2 See 2008/3111 for particulars.

A new bathymetry grid for the Gulf of Papua and Northern Australia was produced for the area 137°-150°E, 6°-14°S, with 0.001° cell size using a minimum curvature spline under tension. New multibeam sonar bathymetry data and STRM topography added much needed detail to a region of the seabed where previously little was known. In shallow Australian waters bathymetry derived from Landsat satellite imagery was used to supplement traditionally acquired bathymetry data.

Map produced for the Australian Fisheries Management Authority showing the logged positions of Vessel Immacolata on the 12th and 13th September 2007 on a background on AUS808 and AUS809.

Map compiled on request from AGS Native Title Case QUD6040/2001 Proclamation 5 See 2008/3111 for particulars.