[An automated measurement of the galaxies spectra of LAMOST].
To measure redshifts of the marge amount of galaxies' spectra automatically is the main goal of the data processing for the LAMOST project (Large Sky Area Multi-Object Optical Fiber Spectroscopic Telescope). A method called PCAZ can be applied to measure the very small redshifts (generally z < 0.2) due to the restriction of the wavelength range of the templates that are composed to make orthogonal templates. In the present article, the authors break the restriction by improving PCAZ method according to the characteristic of LAMOST spectra. Applying this new method to the SDSS data, more than 90% of the results are correct. The maximum limitation for redshift measurement of this new method depends on the wavelength range of the templates and the S/N of the blue parts of the spectra. According to the spectral feature of LAMOST, the authors can measure the galaxies with z < 0.8 correctly. From the experiment the authors concluded: first, this method can be used to measure the redshift of LAMOST spectra; second, the authors need to compose self-contained templates of various galaxies (UV-IR) to measure the survey redshift; finally, the S/N of the blue end of the spectra influences the measurement of the large redshift.
Zhu
Guang-hua
GH
National Astrophysics Observatory of China, Beijing 100012, China.
Luo
A-Li
AL
Zhao
Yong-heng
YH
D000465:Algorithms; D005336:Fiber Optic Technology / Q000295:instrumentation / Q000379:methods*; D055608:Galaxies; D055100:Optical Fibers; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods*