Spatial correlation between H alpha emission and infrared cirrus

Cross-correlation of the DIRBE 100 mu u-m survey with previously published H alpha maps tests correlations between far-infrared dust and the warm ionized interstellar medium in different regions of the sky. A 10 degrees X 12 degrees patch at Galactic latitude b=-21 degrees shows a correlation slope a(0)=0.85+/-0.44 Rayleighs MJy(-1) sr significant at 97% confidence. A set of H alpha images over the north celestial polar cap yields a weaker correlation slope a(0)=0.34+/-0.33 Rayleighs MJy(-1) sr. Combined with observations from microwave anisotropy experiments, the data show roughly similar correlations on angular scales 0.degrees 7 to 90 degrees. Microwave experiments may observe more emission per unit dust emission than are traced by the same structures observed in H alpha. (C) 1997 American Astronomical Society.