We describe the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) Early Re- lease Science (ERS) observations in the Great Observatories Origins Deep Survey (GOODS) South eld. The new WFC3 ERS data provide calibrated, drizzled mosaics in the mid-UV lters F225W, F275W, and F336W, as well as in the near-IR lters F098W (Ys), F125W (J), and F160W (H) in 1{2 HST orbits per lter. Together with the existing HST Advanced Camera for Surveys (ACS) GOODS-South mosaics in the BVi\u27z\u27 lters, these panchromatic 10-band ERS data cover 40{50 square arcmin from from 0.2-1.7 m in wavelength at 00:007{ 000 :15 FWHM resolution and 000 :090 multidrizzled pixels to depths of AB\u3c 26.0{27.0 mag (5-sigma) for point sources, and AB\u3c 25.5{26.5 mag for compact galaxies. In this paper, we describe: a) the scientic rationale, and the data taking plus reduction procedures of the panchromatic 10-band ERS mosaics; b) the procedure of generating object catalogs across the 10 dierent ERS lters, and the specic star-galaxy separation techniques used; and c) the reliability and completeness of the object catalogs from the WFC3 ERS mosaics. The excellent 00:007{00:015 FWHM resolution of HST/WFC3 and ACS makes star- galaxy separation rather straightforward over a factor of 10 in wavelength to AB\u3c 25{26 mag from the UV to the near-IR, respectively. Our main scientic results are: 1) We present the resulting Galactic star counts and galaxy counts in 10 dierent lters. From the ERS data, these could be accurately determined from AB\u2719 mag to AB\u3c 26 from the mid-UV to the near-IR, respectively. 2) Both the Galactic stars counts and the galaxy counts show mild but signicant trends of decreasing count slopes from the mid{UV to the near-IR over a factor of 10 in wavelength. 3) We combine the 10-band ERS counts with the panchromatic GAMA counts at the bright end (10\u3c AB\u3c 20 mag), and with the ultradeep BVizYJH HUDF counts and other avail- able HST UV counts at the faint end (24\u3c AB\u3c 30 mag). The galaxy counts are now well measured over the entire magnitude range 10\u3c AB\u3c 30 mag from 0.2{2 m in wavelength. 4)We t simple galaxy evolution models to these panchromatic galaxy counts over this entire ux range, using the best available 10-band local galaxy luminosity functions (LFs) from the GAMA survey, as well as simple prescriptions of luminosity and/or density evolution. While these models can explain each of the 10-band counts from 10\u3c AB\u3c 30 mag well, no single one of these simple models can explain the counts over this entire ux range in all 10 lters simultaneously. 5) The 10-band panchromatic ERS data base is very rich in structural information at all rest-frame wavelengths where young or older stars shine during the peak epoch in the cosmic star-formation rate (z\u271{2), and constitutes a unique new HST data base for the community to explore in the future
