VLBI schedules for Galileo Frame Tie Study

Description

The dataset contains Very Long Baseline Interferometry (VLBI) schedules in form of NGS files that include observations of both quasars and Galileo satellites are were created with the scheduling software VieSched++ (version v1.3.1; Schartner and Böhm 2019, available on GitHub). These schedules are used to find the optimal distribution of VLBI transmitters (VT) in the Galileo space segement for frame ties. Therefore different numbers and distributions of Galileo satellites being equipped with a VT are investigated. The scenarios having either one, two or three satellites of the Galileo space segment equipped with a VT are investigated. 

Context and methodology

In total, six different satellite configurations ("scenarios") are considered, varying in the number and orbital plane distribution of Galileo satellites equipped with a VT:

1A – 1 satellite with VT in plane A

1A1B – 1 satellite with VT in plane A and 1 in plane B

2A – 2 satellites with VT in plane A

1A2B – 1 satellite with VT in plane A and 2 in plane B

3A – 3 satellites with VT in plane A

1A1B1C – 1 satellite with VT in each of the planes A, B, and C

For each scenario, different proportions of satellite observations relative to the total number of observations are tested. These satellite-to-quasar observation ratios range from 10% to 60%, except for scenarios 1A and 1A1B, for which only 10% to 40% are tested due to limited visibility of the satellite(s).

Each schedule file is named according to the scenario and the satellite observation ratio. For example:

2A_10p refers to the scenario with two satellites in plane A and 10% satellite observations.

1A1B_30p refers to the scenario with one satellite in plane A and one in plane B and 30% satellite observations.

### 数据集说明
本数据集包含以NGS文件格式存储的甚长基线干涉测量（Very Long Baseline Interferometry, VLBI）观测调度方案，涵盖类星体与伽利略卫星的观测任务。该调度方案由调度软件VieSched++（版本v1.3.1；Schartner与Böhm, 2019，开源于GitHub）生成。本数据集用于探索伽利略航天段内甚长基线干涉测量发射机（VLBI Transmitter, VT）的最优布设方案，以实现参考架联结。为此，研究了搭载VT的伽利略卫星的不同数量与轨道分布情况，共涉及航天段内1颗、2颗或3颗搭载VT的伽利略卫星的场景。

### 背景与研究方法
本次研究共考虑6种不同的卫星配置（即"场景"），其差异体现在搭载VT的伽利略卫星的数量与轨道面分布上：
1. 1A：轨道面A内1颗搭载VT的卫星
2. 1A1B：轨道面A内1颗、轨道面B内1颗搭载VT的卫星
3. 2A：轨道面A内2颗搭载VT的卫星
4. 1A2B：轨道面A内1颗、轨道面B内2颗搭载VT的卫星
5. 3A：轨道面A内3颗搭载VT的卫星
6. 1A1B1C：轨道面A、B、C内各1颗搭载VT的卫星

针对每个场景，我们测试了卫星观测任务占总观测任务的不同比例。卫星与类星体的观测占比范围为10%至60%；但由于单颗或两颗卫星的可见性受限，场景1A与1A1B仅测试了10%至40%的观测占比。

每个调度文件的命名规则遵循场景名称与卫星观测占比，例如：
- `2A_10p` 对应轨道面A内2颗搭载VT的卫星、卫星观测占比为10%的场景；
- `1A1B_30p` 对应轨道面A内1颗、轨道面B内1颗搭载VT的卫星、卫星观测占比为30%的场景。