Massive star formation in the outer Galaxy: S284

S284 is a diffuse HII region located in the anti-centre of the galactic disk (l=212, b=−1.3), at a distance of 5.5 kpc and it is relatively isolated. S284 harbours a cluster of stars in its centre known as Dolidze 25 (also known as C 0642+0.03). A spectroscopic study of the cluster sources (Lennon et al. 1990, A&A, 240, 349) revealed: a) the spectral types of these central sources and b) the low metallicity of the cluster (a factor six lower than the solar metallicity). The age of the cluster (6 Myr) has been determined through isochrone fitting of precision photometry (Turbide & Moffat, 1993, AJ, 105, 1831).