Extending the ICRF to Higher Radio Frequencies
Résumé
We present astrometric and imaging results for compact extragalactic objects observed with the Very Long Baseline Array at radio frequencies of 24 and 43 GHz. Data were obtained from ten 24-hour observing sessions made over an approximately 5-year period. These observations were motivated by the need to extend the International Celestial Reference Frame to higher radio frequencies to enable improved deep space navigation after 2015 and to improve state-of-the-art astrometry. With observations over five years we have achieved a precision at 24 GHz approaching that of the ICRF but unaccounted for systematic errors such as residual tropospheric and ionospheric refraction limit the overall accuracy of the catalogs. We conclude that the reduction in the effects due to source structure gained by observing at higher frequencies will result in an improved celestial reference frame and a pool of high-quality fiducial reference points for use in spacecraft navigation over the next decade.