One of the core products of VLBI is the rapid determination of the Earth rotation parameter, expressed through dUT1. Multiple so-called Intensive observing programs exist that are observing dUT1 on a regular basis. Within this work, a detailed overview over the last five years of the VLBI Intensive observing programs INT2 and INT3 is provided. INT2 sessions are typically observed with a single baseline using a recording rate of \({256}\,\hbox {Mbps}\) while INT3 sessions are multi-baseline Intensives with up to five stations and a recording rate of \({1}\,\hbox {Gbps}\). The median dUT1 precision estimated from INT2 sessions is \({10.5}\,{\mu }\hbox {s}\) while it is \({5.9}\,\mu \hbox {s}\) for INT3 sessions. The best performing INT2 baseline is between station MK-VLBA and WETTZELL with a median dUT1 formal error of \({6.4}\,\mu \hbox {s}\) and showing only a small bias of \({-2.5}\,\mu \hbox {s}\) w.r.t. the JPL EOP2 series. Starting in 2019, the scheduling strategy of the INT3 sessions was significantly changed, leading to a reduction in the estimated average dUT1 formal errors by 25 % for 4-station sessions and 45 % for 5-stations sessions. Mid-2020, the same change was performed for INT2 sessions, leading to a reduction in the average dUT1 mean formal error of up to 44 % for the baseline between MK-VLBA and WETTZELL. It is further revealed that the precision of single-baseline INT3 analysis is not significantly better than its INT2 counterpart, although a four-times higher data-rate is used. The reason for this is differences in scheduling optimization. On average, the mean formal error of the best single-baseline INT3 analysis is 50 % higher compared to utilizing the whole network. Besides analyzing dUT1 formal errors, the latency of the dUT1 results is compared for three analysis centers. For INT3 sessions, results are typically available within 24 hours, while it takes two to three days for INT2 sessions, due to observations occurring on weekends. Overall, this work provides detailed insight into the INT2 and INT3 session performances while revealing a strong positive trend in the precision of dUT1 measurements over the last years due to changes in the scheduling strategy.

VLBI的核心产品之一是快速确定地球自转参数，用dUT1表示。存在多个定期观测 dUT1 的所谓密集观测计划。在这项工作中，提供了过去五年 VLBI 强化观测计划 INT2 和 INT3 的详细概述。INT2 会话通常使用单个基线观察，记录速率为\({256}\,\hbox {Mbps}\)，而 INT3 会话是多基线密集型，最多五个站点，记录速率为\({1 }\,\hbox {Gbps}\)。从 INT2 会话估计的中值 dUT1 精度是\({10.5}\,{\mu }\hbox {s}\)而它是\({5.9}\,\mu \hbox {s}\)对于 INT3 会话。表现最好的 INT2 基线在 MK-VLBA 和 WETTZELL 站之间，dUT1 形式误差的中位数为\({6.4}\,\mu \hbox {s}\)，并且仅显示出小的偏差\({-2.5}\ ,\mu \hbox {s}\)Wrt JPL EOP2 系列。从 2019 年开始，INT3 会议的调度策略发生了重大变化，导致 4 站会议的估计平均 dUT1 形式错误减少了 25%，5 站会议减少了 45%。2020 年年中，对 INT2 会话进行了相同的更改，导致 MK-VLBA 和 WETTZELL 之间基线的平均 dUT1 平均形式误差减少了高达 44%。进一步显示，单基线 INT3 分析的精度并不明显优于 INT2 分析，尽管使用了高四倍的数据速率。原因是调度优化的差异。与使用整个网络相比，最佳单基线 INT3 分析的平均形式误差平均高出 50%。除了分析 dUT1 形式错误，比较了三个分析中心的 dUT1 结果的延迟。对于 INT3 会议，通常会在 24 小时内获得结果，而对于 INT2 会议则需要两到三天，因为观察发生在周末。总体而言，这项工作提供了对 INT2 和 INT3 会话性能的详细洞察，同时揭示了由于调度策略的变化，过去几年 dUT1 测量精度的强烈积极趋势。