扣除天光背景的好坏是影响谱线信噪比很重要的因素, 同时由于天光光纤数量有限以及光谱仪漂移等多方面因素的影响导致减天光是光纤光谱数据处理中公认的难点。 目前已有的减天光方法主要是针对全谱的天光成分扣除, 没有关注在特殊谱线位置上的局部天光情况, 尤其是低红移类星体非常重要的［OIII］线附近的天光背景。 探索了一种局部精细的天光背景扣除方法, 解决了类星体中Hβ-［OIII］的宽线经常受到减天光精度干扰的问题。 利用LAMOST减天光前的原始流量以及相对流量改正数据, 根据同一观测天区的超级天光光谱对背景进行扣除。 实验结果表明, 在不同红移类星体中, 该方法减天光后Hβ-［OIII］区间的光谱质量相对于原始LAMOST光谱批处理程序都有了明显的提高, 这更有利于后续的谱线分析, 同时为少部分LAMOST光谱批处理程序没处理好的特殊光谱提供了补充的解决方法。 该方法目前已应用于搜寻双峰活动星系核候选体的预处理中。

At present, most sky-subtraction methods focus on the full spectrum, not the particular location, especially for the backgroud sky around ［OIII］ line which is very important to low redshift quasars. A new method to precisely subtract sky lines in local region is proposed in the present paper, which sloves the problem that the width of Hβ-［OIII］ line is effected by the backgroud sky subtraction. The exprimental results show that, for different redshift quasars, the spectral quality has been significantly improved using our method relative to the original batch program by LAMOST. It provides a complementary solution for the small part of LAMOST spectra which are not well handled by LAMOST 2D pipeline. Meanwhile, This method has been used in searching for candidates of double-peaked Active Galactic Nuclei.