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The Hubble Deep Field (HDF) is the deepest set of multicolor opticalphotometric observations ever undertaken, and offers a valuable data set withwhich to study galaxy evolution. Combining the optical WFPC2 data withground-based near-infrared photometry, we derive photometrically estimatedredshifts for HDF galaxies with J<23.5. We demonstrate that incorporating thenear-infrared data reduces the uncertainty in the estimated redshifts byapproximately 40% and is required to remove systematic uncertainties within theredshift range 1<z<2. Utilizing these photometric redshifts, we determine theevolution of the comoving ultraviolet (2800 A) luminosity density (presumed tobe proportional to the global star formation rate) from a redshift of z=0.5 toz=2. We find that the global star formation rate increases rapidly withredshift, rising by a factor of 12 from a redshift of zero to a peak at z~1.5.For redshifts beyond 1.5, it decreases monotonically. Our measures of the starformation rate are consistent with those found by Lilly et al. (1996) from theCFRS at z<1, and by Madau et al. (1996) from Lyman break galaxies at z > 2, andbridge the redshift gap between those two samples. The overall star formationor metal enrichment rate history is consistent with the predictions of Pei andFall (1995) based on the evolving HI content of Lyman-alpha QSO absorption linesystems.Comment: Latex format, 10 pages, 3 postscript figures. Accepted for  publication in Ap J Letter

The Evolution of the Global Star Formation History as Measured from the Hubble Deep Field