长期视宁度监测DIMM系统设计方案  

A Design of a DIMM System for Long-Term Seeing Measurement

作　　者：辛玉新[1,2] 范玉峰[1,2] 伦宝利[1,2] 张瑞龙[1,2] 

机构地区：[1]中国科学院云南天文台,云南昆明650011 [2]中国科学院天体结构与演化重点实验室,云南昆明650011

出　　处：《天文研究与技术》2012年第4期397-404,共8页Astronomical Research & Technology

基　　金：云南省基础研究面上项目(2009CD121)资助

摘　　要：视宁度参数r0是现代天文选址中需要测量的一个重要物理量,而差分像视宁度监测仪(Differential Image Motion Monitor,DIMM)是目前普遍采用的测量视宁度参数r0的天文仪器。详细介绍了可进行长期视宁度监测的DIMM系统的设计方案,重点讨论了目标星指向、自动导星、自动测量和数据保存等部分。长期视宁度监测DIMM系统的部署,有助于分析已选站址或候选站址的本征视宁度,评价一个站址的成像质量。The Fried （or seeing） parameter r0 is very important in modern site surveys, and a DIMM （Differential-Image Motion Monitor） is a general-purpose equipment to measure r0. We introduce a design of a remote-control DIMM system in detail, including target-star pointing, automatic guiding, automatic measurement, data storage, and etc. Employing a DIMM system to monitor long-term seeing will be helpful to find the intrinsic site seeing for a checked or candidate site, and to evaluate the imaging quality. We use a 12 telescope--Meade LX2OOGPS for measuring the atmospheric seeing. With conventional methods we would have to manually adjust the telescope pointing for tracking the target during the measurement, as the tracking accuracy of the small telescope is not excellent. However, we often need to observe a bright star for several hours for r0 and to keep the target in the field of view of the CCD. We adopt a more effective method, i.e. to install a guide camera for the telescope. For our remote DIMM system we choose the LPI as the guide camera （instead of DSI or others ） and the Guider Master as our guiding software, which leads to a very good performance. Through the Remote Desktop Protocol or VNC, the system acquires a remote observation mode, which brings about many advantages for long-term seeing measurement. In addition, the system is capable of real time processing of images, which are recorded at a rate of 250 frames per 10 seconds with the exposure time of 8 miliseconds per frame. In this way we can measure nearly six sets of r0 values per minute. In the night of April 9, 2011 we measured the seeing at the Phoenix Mountain, Kunming using our DIMM system, and obtained the r0 curve from 20 ： 50 to 2 ： 30. We also obtained the FWHM values of stellar images （ for targets not identical to those for the DIMM） of the lm telescope of the Yunnan Observatory. We find a good correlation between the seeing values measured by the DIMM and the FWHM values measured by the 1 m telescope. This indicates that

关 键 词：视宁度 DIMM 自动导星 本征视宁度 

分 类 号：P126[天文地球—天体测量]