To assure high pointing precision of the Tianma radio telescope (TMRT), new models based on a inclinometer measurement system are added to the classical pointing model. This involves four main tasks. Firstly, the inclinometer measurement system is set up and its precision is evaluated. Secondly, a feedback control strategy for pointing error for the turbulences of uneven azimuth track and thermal deformations of alidade is implemented. Thirdly, after removing the linear effect of uneven track, sine fitting inclinometer data obtains the model of nonlinear effect of azimuth-track-level unevenness. The nonlinear effect is less than ±5 arc-sec. The azimuth angles associated with large pointing error show a good agreement with those corresponding to poor track unevenness. Finally, the TMRT inclinometers monitor the effect of thermal deformations of alidade on the pointing precision of elevation from stow position, to observing almost motionless radio source, to arbitrary postures of radio telescope. The measured data after subtracting other affected factors of inclinometer including intrinsic drift, azimuth-track unevenness, variation of the center of gravity have similar tendency with the simulated results of finite element model (FEM). Applying established real-time modified model to observe the radio source 2334 + 8226, the checking results show that the pointing precision improved 65%.

中文翻译：

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用测斜仪测量系统提高天马射电望远镜指向精度

为保证天马射电望远镜（TMRT）的高指向精度，在经典指向模型的基础上增加了基于测斜仪测量系统的新模型。这涉及四个主要任务。首先，搭建测斜仪测量系统并对其精度进行评价。其次，针对不均匀方位轨迹的湍流和alidade的热变形，实现了指向误差的反馈控制策略。第三，在去除不均匀轨道的线性效应后，正弦拟合测斜仪数据得到方位轨道级不平整度非线性效应模型。非线性效应小于±5 弧秒。与大指向误差相关的方位角与对应于较差轨道不平整度的方位角显示出良好的一致性。最后，TMRT 倾角仪监测 alidade 的热变形对从收起位置到观察几乎静止的射电源到射电望远镜任意姿势的仰角指向精度的影响。减去固有漂移、方位轨道不平度、重心变化等测斜仪其他影响因素后的实测数据与有限元模型（FEM）模拟结果具有相似的趋势。应用建立的实时修正模型对射源2334+8226进行观测，检测结果表明指向精度提高了65%。减去固有漂移、方位轨道不平度、重心变化等测斜仪其他影响因素后的实测数据与有限元模型（FEM）模拟结果具有相似的趋势。应用建立的实时修正模型对射源2334+8226进行观测，检测结果表明指向精度提高了65%。减去固有漂移、方位轨道不平度、重心变化等测斜仪其他影响因素后的实测数据与有限元模型（FEM）模拟结果具有相似的趋势。应用建立的实时修正模型对射源2334+8226进行观测，检测结果表明指向精度提高了65%。