乌鲁木齐南山站25m射电望远镜在6cm波段对地面辐射的总功率响应

The Total Power Response to the Ground Radiation at 6cm Wavelength of the Urumqi 25m Radio Telescope at Nanshan Station

利用乌鲁木齐南山站25m望远镜6cm系统对观测站周边的地面辐射做了仔细的观测。发现该系统对地面辐射的响应在天空的不同方向有显著的变化。望远镜俯仰为8°时,南方由于高山的影响,对地面辐射的响应已经饱和;甚至在望远镜指向高俯仰（60°）时,总功率响应随不同方位的起伏也可达到0.3K,大于银道面0.01-0.1K的响应,因此它对射电天文观测有显著的影响。根据这些观测数据,建立了6cm系统在不同方向处对地面辐射的响应模型。此模型能够大致描述地面辐射的特征,但尚不能用来完全消除地面辐射的影响。

We present the result of intensive observations of the ground radiation around the Nanshan Station using the 6cm system of Urumqi 25m radio telescope. The response of the system to the ground radiation varies significantly in different directions of the sky. The response in the southwest direction, where there are many mountains, was saturated when the telescope pointed to the elevation of 8° ; at the elevation of 60° the response to the ground radiation still varied at a level of 0.3 K, larger than the system response to the Galactic Plane of 0.01 - 0.1K. Therefore the ground radiation affects the radio observation seriously. Using the observational data, we constructed a simple template of the ground radiation of the 6cm system in the directions of the sky. However, the accuracy of the template remains inadequate for real observations.