Chapman, S. C.Barger, A. J.Cowie, L. L.Scott, D.Borys, C.Capak, P.Fomalont, E. B.Lewis, G. F.Richards, E. A.Steffen, A. T.Wilson, G.Yun, M.2014-03-122014-03-122003-03Chapman, S. C., A. J. Barger, L. L. Cowie, D. Scott, et al. 2003. "The Properties of Microjansky Radio Sources in the HDF-N, SSA13, and SSA22 Fields." The Astrophysical Journal 585(1): 57-660004-637Xhttp://dx.doi.org/10.1086/345980http://hdl.handle.net/10222/45502(abridged) We present multiwavelength observations for a large sample of microjansky radio sources detected in ultradeep 1.4GHz maps centered on the Hubble Deep Field-North (HDF-N) and the Hawaii Survey Fields SSA13 and SSA22. Our spectroscopic redshifts for 169 radio sources reveal a flat median redshift distribution, and these sources are hosted by similarly luminous optical L* galaxies, regardless of redshift. This is a serious concern for radio estimates of the local star formation rate density, as a substantial fraction of the ultraviolet luminosity density is generated by sub-L* galaxies at low redshifts. From our submillimeter measurements for 278 radio sources, we find error-weighted mean 850micron fluxes of 1.72$\pm$0.09 mJy for the total sample, 2.37$\pm$0.13 mJy for the optically-faint (I>23.5) subsample, and 1.04$\pm$0.13 mJy for the optically-bright (I3\sigma) detect in the submillimeter 50 of the radio sources, 38 with I>23.5. Spectroscopic redshifts for three of the I23.5. We also find that 66\pm7% of the S850>5 mJy (>4\sigma) sources are radio-identified. We find that millimetric redshift estimates at low redshifts are best made with a FIR template intermediate between a Milky Way type galaxy and a starburst galaxy, and at high redshifts with an Arp220 template.article585157