Speakers
Description
Astrometry at the very highest of frequencies is an unexplored frontier for VLBI observations. Astrometry is equally vital to connect observations at different times and different frequencies. The former is used for measuring proper motions and parallaxes to derive distances to the targets - and thus their physical characteristics.
The latter is to reference two images at different frequencies together, which is equally important. No spectral index or rotation measure is valid if the observations are not registered.
One of the exciting new facilities that will be available shortly is the updated Event Horizon Telescope (EHT-2030). The plan is that that multiple frequencies will be observed simultaneously; 86-, 230- and 340-GHz. Multi-frequency observations result in a transformational boost in the capabilities of the EHT, providing the vital phase referenced registration between frequencies.
We will describe how this new capability will allow ultra-precise bona-fide astrometric studies, based on simulations. We will report on our first attempts to apply frequency phase transfer at mm-wavelengths (86 to 230GHz); three demonstrations have been made, two of which are now published and the third is being correlated. These are allowing to demonstrate the potential and to discover the hidden issues to be addressed.
In addition we will discuss MultiView astrometry, which was designed for `lower' frequencies, but we are also pushing it towards mm-wavelengths, with observations at 43GHz and proposals for 86GHz.
The combination of these techniques would offer all varieties of astrometric measurements at these extreme frequencies, and thus investigations of the most extreme of physical conditions.
