Peering through the OH Forest: public release of sky-residual subtracted spectra for SDSS DR7
arXiv:1010.2500
Abstract
The Sloan Digital Sky Survey (SDSS) automated spectroscopic reduction pipeline provides >1.5 million intermediate resolution, R~2000, moderate signal-to-noise ratio (SNR), SNR~15, astronomical spectra of unprecedented homogeneity that cover the wavelength range 3800-9200AA. However, there remain significant systematic residuals in many spectra due to the sub-optimal subtraction of the strong OH sky emission lines longward of 6700AA. The OH sky lines extend over almost half the wavelength range of the SDSS spectra, and the SNR over substantial wavelength regions in many spectra is reduced by more than a factor two over that expected from photon counting statistics. Following the OH line subtraction procedure presented in Wild & Hewett (2005), we make available to the community sky-residual subtracted spectra for the Sloan Digital Sky Survey Data Relase 7. Here we summarise briefly the method, including minor changes in the implementation of the procedure with respect to WH05. The spectra are suitable for many science applications but we highlight some limitations for certain investigations. Details of the data model for the sky-residual subtracted spectra and instructions on how to access the spectra are provided.
arXiv comment11 pages, 5 figures. Spectra may be downloaded from the JHU SDSS server http://www.sdss.jhu.edu/skypca/spSpec, additionally the QSOs can be found on the DR7 Value Added Catalogue web page: http://www.sdss.org/dr7/products/value_added/index.html#quasars
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