云南暗弱天体光谱及成像仪长缝光谱研究

The Study of the YFOSC Long-Slit Spectrograph

云南暗弱天体光谱及成像仪(Yunnan Faint-Object Spectrograph and Camera,YFOSC)是一台能够快速切换工作模式,进行天文成像及光谱观测的仪器。其中长缝光谱作为该仪器的主要光谱观测模式广泛应用于点源以及面源的分光测量研究。通过测量该模式下YFOSC系统的波长响应曲线,各块光栅的波长范围,并对定标灯谱进行波长证认,同时在考虑大气吸收以及望远镜效率的情况下给出了曝光时间曲线,为观测者更好地使用该仪器提供参考。最后以近期拍摄的一条超新星光谱为例,介绍长缝光谱模式的实际观测能力。

The YFOSC （Yunnan Faint-Object Spectrograph and Camera） is a powerful instrument for astronomical research which can quickly switch its working mode from the photometric to the spectrophotometric. A main spectroscopic mode is using a long slit with a low-resolution Grism （a combination of grating and prism） to observe point sources or extended objects. This paper first describes the system response function and the wavelength coverage of each grism. We then describe the calibration of the wavelengths of three lamps for observation. We also give the relation between exposure time and object magnitude for practical reference. In the past year we carried out many observations with the YFOSC and obtained some useful data for objects such as supernovae, QSOs, and normal galaxies. We have also used long-slit modes to scan some extended objects such as nearby galaxies to find their velocity fields. We finally present a spectrum from a supernova as an example of application of this instrument.