Abundance determination in HII regions from spectra without the
  [OII]3727+3729 line
  We suggest an empirical calibration for determination of oxygen and nitrogen
abundances and electron temperature in HII regions where the [OII]3727+3729
line (R_2) is not available. The calibration is based on the strong emission
lines of OIII, NII, and SII (NS calibration) and derived using the spectra of
HII regions with measured electron temperatures as calibration datapoints. The
NS calibration makes it possible to derive abundances for HII regions in nearby
galaxies from the SDSS spectra where R_2 line is out of the measured wavelength
range, but can also be used for the oxygen and nitrogen abundances
determinations in any HII region independently whether the nebular oxygen line
[OII]3727+3729 is available or not. The NS calibration provides reliable oxygen
and nitrogen abundances for HII regions over the whole range of metallicities.
