Arthur Niell
Principle Research Scientist, MIT Haystack Observatory
My association with Arecibo began in 1966 when, as a grad student in CRSR at Cornell, I spent the summer searching chart recordings to look for lunar occultation candidates.ˆà I eventually obtained a Ph. D. in Applied Physics from Cornell in the area of Radio Astronomy based on observations made at Arecibo.
Following a year at QueenòÀÙs University in Canada, I moved to the Jet Propulsion Laboratory as a post-doc where for two years I participated in monthly 24-hour Very Long Baseline Interferometry (VLBI) sessions.ˆà Through these sessions, by working with great people from MIT and GSFC one month and from Caltech and NRAO the other, I was introduced to the use of VLBI for both astronomy and geodesy.ˆà Equally important, it led to professional and personal associations that continue to this day.
I joined the staff at JPL in 1974 where we developed mobile VLBI systems that were used to make the first cm-level measurements demonstrating the large-scale crustal deformation in the region encompassing the San Andreas Fault.ˆà While at JPL I participated in early VLBI observations of the amazing micro-quasar SS43 and in radio-astrometric measurements of the positions of the Galilean satellites of Jupiter, among other projects.
In 1984 I joined the staff of the MIT Haystack Observatory to work in the geodetic VLBI group, which has funding from NASA to support and improve measurements of changes in the shape of the Earth and it orientation in space.ˆà Much of my effort has been directed to reduction of the deleterious effects of the neutral atmosphere on geodetic measurements.ˆà For the last few years I have concentrated on the development and implementation of a new geodetic VLBI concept designated VLBI2010. It is this development that has brought me back to Arecibo Observatory, as I hope to see the implementation of the VLBI2010 broadband signal chain on the 12m antenna.ˆà Puerto Rico is an important location for a new next generation geodetic VLBI system.
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Abstract: "Arecibo through the eyes of an astronomer turned geodesist"
Puerto Rico is in a highly desirable location from a global geodetic VLBI point of view.ˆà It is located on the Caribbean plate, and it is near the equator.ˆà A geophysical goal of the next generation geodetic observing system is to have at least one observatory on each tectonic plate, and Arecibo will provide this with the implementation of the broadband signal chain on the 12m antenna.ˆà A second benefit of the site is to provide a connection among other antennas in the global network, both between north and south and from east to west.ˆà With the next generation geodetic VLBI system, the accuracy of relative locations on the surface of the Earth is expected to improve to the few millimeter level.ˆà I will describe the new system and discuss some of the benefits to both geodesy and astronomy.