K-band 24-hour EOPs and UT1-UTC Intensives

We investigate the potential for EOP and UT1-UTC measurements at K-band (24 GHz). A ‘K-band collaboration’ has been making regular VLBA K-band astrometry sessions since 2016 for expansion and improvement of the ICRF at K-band. Since 2017, these sessions have been made approximately monthly under the US Naval Observatory’s VLBA 50% time allocation. Though designed for astrometry, these 24-hr sessions also yield accurate EOP measurements.We will compare the K-band EOPs with various other series, such as the IERS C04 series, USNO’s Legacy S/X (2.3/8.4 GHz) series from IVS data, and a USNO series from VLBA S/X astrometry sessions. Over the next few years, the 10 VLBA antennas will be equipped with broadband receivers capable of observing from 8 to 40 GHz, and could thus simultaneously observe at X/K- or X/Ka- or even X/K/Ka-bands, allowing better ionosphere calibration than the current application of ionosphere corrections from GNSS ionosphere maps. To explore the potential for K- or X/K-band UT1-UTC measurements, we ran a series of four 4-hour VLBA K-band UT1-UTC Intensive-type sessions, in July 2023, spaced one week apart. We have processed these into sets of 16 1-hr single-baseline databases for several long baselines. We will show the comparison of the UT1-UTC solutions and formal errors versus other UT1-UTC series, such as the IVS S/X UT1-UTC series and USNO’s VLBA UT1-UTC series.