Improved spectral line measurements of the SDSS galaxy spectra

We have established a database of galaxy spectral line strengths for the SDSS database using an improved line measuring method. Our work includes the entire SDSS DR7 galaxies within redshift of 0.2. The absorption line strengths measured by the SDSS pipeline are seriously contaminated by emission filling. Our code, GANDALF (gas and absorption line fitting code) performs more accurate measurements by effectively separating emission lines from absorption lines. A significant improvement has also been made on the velocity dispersion measurement, more notably in late-type galaxies. We have also identified a number of broad line region galaxies which were misclassified as normal galaxies by the SDSS pipeline. We developed an effective method measuring their line strengths. The database will be provided with new parameters that are indicative of the line strength measurement quality. In addition, we made galaxy templates for the Hubble sequence. The database will be useful for many fields of galaxy studies including star formation and AGN activities.