We have re-analyzed continuum and recombination lines radio data available in the literature in order to derive the luminosity function ( LF ) of Galactic HII regions .
The study is performed by considering the first and fourth Galactic quadrants independently .
We estimate the completeness level of the sample in the fourth quadrant at 5 Jy , and the one in the first quadrant at 2 Jy .
We show that the two samples ( fourth or first quadrant ) include , as well as giant and super-giant HII regions , a significant number of sub-giant sources .
The LF is obtained , in each Galactic quadrant , with a generalized Schmidt ’ s estimator using an effective volume derived from the observed spatial distribution of the considered HII regions .
The re-analysis also takes advantage of recently published ancillary absorption data allowing to solve the distance ambiguity for several objects .
A single power-law fit to the LFs retrieves a slope equal to -2.23 \pm 0.07 ( fourth quadrant ) and to -1.85 \pm 0.11 ( first quadrant ) .
We also find marginal evidence of a luminosity break at L _ { knee } = 10 ^ { 23.45 } erg s ^ { -1 } Hz ^ { -1 } for the LF in the fourth quadrant .
We convert radio luminosities into equivalent H { \alpha } and Lyman continuum luminosities to facilitate comparisons with extra-galactic studies .
We obtain an average total HII regions Lyman continuum luminosity of 0.89 \pm 0.23 \times 10 ^ { 53 } \hbox { sec } ^ { -1 } , corresponding to 30 \% of the total ionizing luminosity of the Galaxy .