LAMOST望远镜平场特性及改进研究

LAMOST DR3 has released more than 5.7 million spectra, and increasing at the rate of 1.2 million each year. DR3 stellar catalog contains stellar parameters for 3.1 million spectra. Theare are quite lot of spectra are failed to measure the parameters due to the bad quality in this mass data set. Sky subtraction is one of key factors affecting the spectral quality, especially for the faint objects that their bightness are close to sky brightness. For the multi-fiber spectra reduction, sky subtraction is based on the precision of flat fielding, which corrects the total throughput of each fiber..In this proposal, firstly I briefly introduce the unique optical design of LAMOST telescope, and the difficulty caused by this to the flat fielding correction. Then the flat fielding method using in the pipeline is briefly presented, and the some exiting problems also been discuseed. Later, with the analysis of the optical properties, I propose three innovative methods for increasing the accuracy of flat fielding correction for LAMOST. The feasibility and the approach of these study works are also been discussed.

LAMOST DR3已经释放了超过570万光谱数据，并正在以每年120万的速度增加。DR3恒星参数星表给出了310万光谱的恒星物理参数。在这海量的光谱数据中，有相当一部分质量不好的光谱没能给出参数信息。减天光是影响光谱质量的最重要因素之一，特别是对亮度接近天光背景的暗源而言。而对于多光纤光谱数据处理，改正光纤传输效率的平场改正是减天光的基础。.本申请书首先简要介绍了LAMOST望远镜光学系统的特殊性，以及由此导致的平场改正问题。然后介绍了目前正在使用的平场改正方法以及光谱数据中与平场相关的一些问题。之后，在分析LAMOST光学特性的基础上，本文创新性地提出了三个提高平场改正精度的方法，并讨论了研究这些改进的途径和可行性问题。

LAMOST望远镜是一台性能独特的大视场光谱巡天望远镜，具有非常高的光谱观测效率。为了获得高光谱获得率，LAMOST望远镜的光学设计给光谱的平场改正和减天光处理带来了困难。主要表现在望远镜的渐晕和光纤的传输效率随观测指向发生动态变化。本项目在完善对望远镜渐晕的理论模型研究的基础上，开展利用与观测同步的激光发射线来进行光纤效率测量和二次平场改正的研究工作。经过测试，完成了同步观测激光发射线，测量激光发射线计算光纤传输效率和构建光纤传输效率模型的完整流程。