LAMOST Spectrograph Response Curves: Stability and Application to flux calibration

Abstract

The task of flux calibration for LAMOST (Large sky Area Multi-Object Spectroscopic Telescope) spectra is difficult due to many factors. For example, the lack of standard stars, flat fielding for large field of view, and variation of reddening between different stars especially at low galactic latitudes etc. Poor selection, bad spectral quality, or extinction uncertainty of standard stars not only might induce errors to the calculated spectral response curve (SRC), but also might lead to failures in producing final 1D spectra. In this paper, we inspected spectra with Galactic latitude |b|>=60 degree and reliable stellar parameters, determined through the LAMOST Stellar Parameter Pipeline (LASP), to study the stability of the spectrograph. To guarantee the selected stars had been observed by each fiber, we selected 37,931 high quality exposures of 29,000 stars from LAMOST DR2, and more than 7 exposures for each fiber. We calculated the SRCs for each fiber for each exposure, and calculated the statistics of SRCs for spectrographs with both the fiber variations and time variations. The result shows that the average response curve of each spectrograph (henceforth ASPSRC) is relatively stable with statistical errors <= 10%. From the comparison between each ASPSRC and the SRCs for the same spectrograph obtained by 2D pipeline, we find that the ASPSRCs are good enough to use for the calibration. The ASPSRCs have been applied to spectra which were abandoned by LAMOST 2D pipeline due to the lack of standard stars, increasing the number of LAMOST spectra by 52,181 in DR2. Comparing those same targets with SDSS, the relative flux differences between SDSS spectra and that of LAMOST spectra with the ASPSRC method are less than 10%, which underlines that the ASPSRC method is feasible for LAMOST flux calibration.

23 pages,22 figures, accepted by ApJS

References in corpus (2)

• An Analysis of the Shapes of Interstellar Extinction Curves. V. The IR-Through-UV Curve Morphology
• Relative Flux Calibration of the LAMOST Spectroscopic Survey of the Galactic Anti-center

Cited by in corpus (13)

• Spectral classification and composites of galaxies in LAMOST DR4
• The study of eleven contact binaries with mass ratios less than 0.1
• A Systematic Analysis of Stellar Populations in the Host Galaxies of Changing-look AGNs
• Strong [OIII]λ5007 emission line compact galaxies in LAMOST DR9: Blueberries, Green Peas and Purple Grapes
• The first photometric and spectroscopic analysis of the extremely low mass ratio contact binary NSVS 5029961
• M Subdwarf Research. II. Atmospheric Parameters and Kinematics
• Intermediate-Mass Black Holes in Green Pea Galaxies (IMBH-GP) I: a Candidate Sample from LAMOST and SDSS
• Unbiased Spectroscopic Study of the Cygnus Loop with LAMOST. I. Optical Properties of Emission Lines and the Global Spectrum
• Photometric and spectroscopic studies of the long period low mass ratio deep contact binary KN Per
• Study on Outliers in the Big Stellar Spectral Dataset of the Fifth Data Release (DR5) of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST)
• Discovery of Five Green Pea Galaxies with Double-peaked Narrow [OIII] Lines
• Looking for Signs of Unresolved Binarity in the Continuum of LAMOST Stellar Spectra
• Characterizing Some Gaia Alerts with LAMOST and SDSS