Group delay precision from these setups is close to the precision reached at geodetic setups. Since 2016–2020, astronomical observations typically cover frequency bands of 256 or 512 MHz. Progress in radio astronomy instrumentation resulted in an increase of recorded bandwidth. However, single-band observations at rather low frequencies such as 5 GHz are affected by the ionospheric refraction, and this limits their usability for geodesy. 2007), processing astronomical data in a geodetic/astrometric mode was feasible and provided good results (Petrov and Taylor 2011). In case the goal of astronomical observation requires wide spanned bandwidth, e.g., for VLBA (Very Long Baseline Array) Imaging and Polarimetry Survey at 5 GHz (Helmboldt et al. A non-contiguous allocation of intermediate frequencies for astronomy projects was rare because usually it was not required, and commonly used software packages, such as AIPS (Greisen 2003), that implemented the fringe fitting procedure do not support direct processing of such data. Although such data were still useful for astrometry (Petrov 2011, 2013), they were too coarse for precise geodesy. As a result, group delay uncertainty at a given signal-to-noise ratio (SNR) was an order of magnitude worse than from geodetic schedules. The use of data for geodesy and astrometry from astronomical programs designed for imaging was not common in the past because four to eight intermediate recorded frequencies (IFs) were usually allocated contiguously, while for geodetic applications the frequencies are allocated as wide as possible. Astronomical schedules usually avoid subarrays. This leads to a substantial reduction of the number of closures in phase and amplitude required for robust imaging. A typical geodetic schedule splits the network into a number of ad hoc subarrays, so a subset of stations observes one source and a subset of other stations observes another source at the same time, and upon completion of integration another subset of stations observes the next source. Unfortunately, geodetic observing schedules are not well suited for producing good quality images. One of the most promising ways to compute the source structure contribution to group delay is to generate images from the same VLBI observations, perform their 2D Fourier transform over spatial coordinates, and use it for calculation of structure delay (see, e.g., Petrov and Kovalev 2017). 2015 Petrov and Kovalev 2017) or even the major (Anderson and Xu 2018) contributor to the error budget in geodetic VLBI. 2002 Tornatore and Charlot 2007 Shabala et al. It was known for long time that source structure is a significant (e.g., Zeppenfeld 1993 Sovers et al. Up to now, the contribution of source structure is not included in routine analysis of VLBI data. Group delay of an extended source observed with very long baseline interferometry (VLBI) differs from the group delay of a point source. We conclude that systematic errors in MOJAVE-5 dataset are low enough for these data to be used as an excellent testbed for further investigations on the radio source structure effects in geodesy and astrometry. We showed that the major factor causing discrepancies in the estimated geodetic parameters is the different scheduling approach of the datasets. the scheduling approach, treatment of the ionospheric delay, and selection of target radio sources. We isolated three major differences between the datasets in terms of their possible impact on the geodetic results, i.e. The wrms of the difference of estimated Earth orientation parameters with respect to the reference IERS C04 time series are a factor of 1.3 to 1.8 worse. We showed that the baseline length repeatability from MOJAVE-5 experiments is only a factor of 1.5 greater than from the dedicated geodetic dataset and still below 1 ppb. We processed a concurrent dedicated VLBA geodesy program observed at 2.3 GHz and 8.6 GHz starting on September 2016 through July 2020 as reference dataset. We investigated the suitability of the astronomical 15 GHz Very Long Baseline Array (VLBA) observing program MOJAVE-5 for estimation of geodetic parameters, such as station coordinates and Earth orientation parameters.
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