天光作为一种主要的噪声, 叠加在目标天体光谱之中, 降低了光谱的信噪比。 经过减天光处理后, 若光谱中仍含有大量强度高的天光残差将不利于对目标光谱的后续分析。 自动识别减天光异常恒星光谱的研究较少, 目前只能通过人工检测的方法去寻找减天光异常的光谱, 效率较低。 首先对影响减天光结果的因素进行分析, 找出减天光异常光谱的特征, 然后提出一种简单有效的方法能够自动识别LAMOST巡天经过Pipeline处理之后仍然存在减天光异常的恒星光谱并检测其位置。 该方法先对光谱进行归一化处理, 然后通过检测天光线附近是否有一定强度的类似发射线或吸收线的残留来判定该天光线位置是否出现减天光异常, 最后得出光谱中所有的减天光异常的天光位置。 通过对LAMOST光谱数据的实验表明, 这种方法可以有效识别出减天光异常的光谱和发现不同残留强度的天光线异常位置, 并且该方法简单易懂, 识别效率高, 可以应用于大量的减天光异常光谱的识别与检测问题。

The skylines, superimposing on the target spectrum as a main noise, will reduce the signal-to-noise ratio of the spectrum. If the spectrum still contains a large number of high strength skylight residuals after sky-subtraction processing, it will not be conducive to the follow-up analysis of the target spectrum. At present, the study on the automatic recognition of the abnormal sky-subtraction stellar spectra is limited in number. We can only find the abnormal sky-subtraction spectra by manual inspection, and this will reduce the speed of detection. This paper analyzes the influence factors of sky-subtraction results and finds the characteristics of the abnormal sky-subtraction spectra. A simple and effective method is proposed to automatic recognize the abnormal sky-subtraction stellar spectra which have been processed with the LAMOST Pipeline processing procedure and find the positions of the abnormal skylines. In this method, all the spectra are normalized first; the abnormal skyline is determined by detecting whether there exits any high strength skyline residuals which are similar to the emission line or absorption line. Finally, all the abnormal skyline positions in the spectra are obtained in this method. The experimental results with the LAMOST spectroscopic dataset show that this method can recognize the abnormal sky-subtraction spectra and find the abnormal skyline positions of different residual strength effectively. In addition, the method is simple and has high recognition efficiency, and can be applied to the automatic detection of abnormal sky-subtraction of large number of spectra.