Single-Band Absolute Astrometry

The ionospheric contribution affects path delay. When simultaneous dual-band observations are used for absolute astrometry, the residual contribution of the ionosphere is at a level of several picoseconds.

But there are two cases when we need to process single band group delays:

a) some observations provided usable data only for one band; b) an entire experiment used only one band. I have developed a novel approach to utilize GNSS TEC maps to get the best solutions for these two cases and provide realistic estimates of residual errors. Applications of this technology is discussed. In particular, the impact of residual ionospheric path delays at K-band on estimates of source positions is quantitatively evaluated and conclusions about advantages and disadvantages of high frequency absolute astrometry are made.