Assessment of the accuracy of daily UT1 determinations by very long baseline interferometry

E-ISSN： 2156-2202|100|B5|8193-8200

ISSN： 0148-0227

Source： Journal Of Geophysical Research, Vol.100, Iss.B5, 1995-05, pp. : 8193-8200

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Abstract

By comparing UT1 determinations from the International Radio Interferometric Surveying intensive program of quasi‐daily, single‐baseline, 1‐hour very long baseline interferometry (VLBI) measurement sessions with coincident, multibaseline 24‐hour VLBI determinations, we estimate the overall accuracy of the intensive UT1 results, averaged over 5.4 years of data, to be ∼52 μs, depending somewhat on the amount of error attributed to the multibaseline results. The largest error contributions are due to interpolated values for polar motion X and y coordinates (<38 μs), short‐term variability in atmospheric propagation (∼48 μs during summers but much less at other times), and extended brightness structures in the radio sources (∼22 μs). Because the atmospheric effect is most pronounced during summers, the UT1 accuracy of the intensives is ∼47 μs most of the year but degrades to ∼67 μs during the third quarter of each year.