Over 24 000 δ Scuti Stars in the Galactic Bulge and Disk from the OGLE Survey

We present the largest collection of δ Scuti-type stars in the Milky Way. Together with the recently published OGLE collection of δ Sct variables in the inner Galactic bulge, our sample consists of 24 488 objects distributed along the Milky Way plane, over galactic longitudes ranging from about -170^o to +60^o. The collection data include the I- and V-band time-series photometry collected since 1997 during the OGLE-II, OGLE-III, and OGLE-IV surveys. We show the on-sky distribution of δ Sct stars in the Galactic bulge and disk, discuss their period, luminosity and amplitude distributions, present Petersen diagram for multimode pulsators, distinguish 34 δ Sct stars in eclipsing and ellipsoidal binary systems, and list probable members of globular clusters.