Oxygen and helium abundances in Galactic HII regions - I. Observations

Absolute integrated line fluxes of HII regions have been measured using a Fabry-Perot spectrophotometer. We describe the observations and calibration procedures. Fluxes are given for 36 HII regions with Galactocentric distances ranging from 6.6 to 17.7kpc. Several emission lines have been measured, mainly [OII] λλ3726 and 3629, Hβ, [OIII] λ5007, Hei λ5876 and Hα. The very faint [OIII] λ4363 line has been measured in six regions, allowing a direct determination of the electron temperature. New photometric distances have been derived based on data from the literature. A discussion of these results in terms of extinction, electron density and temperature, and oxygen and helium abundances is given in Paper II.