MAPS OF DUST INFRARED-EMISSION FOR USE IN ESTIMATION OF REDDENING ANDCOSMIC MICROWAVE BACKGROUND-RADIATION FOREGROUNDS

We present a full-sky 100 mu m map that is a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and co nfirmed point sources removed. Before using the ISSA maps, we remove t he remaining artifacts from the IRAS scan pattern. Using the DIRBE 100 and 240 mu m data, we have constructed a map of the dust temperature so that the 100 mu m map may be converted to a map proportional to dus t column density. The dust temperature varies from 17 to 21 K, which i s modest but does modify the estimate of the dust column by a factor o f 5. The result of these manipulations is a map with DIRBE quality cal ibration and IRAS resolution. A wealth of filamentary detail is appare nt on many different scales at all Galactic latitudes. In high-latitud e regions, the dust map correlates well with maps of H I emission, but deviations are coherent in the sky and are especially conspicuous in regions of saturation of H I emission toward denser clouds and of form ation of H, in molecular clouds. In contrast, high-velocity H I clouds are deficient in dust emission, as expected. To generate the full-sky dust maps, we must first remove zodiacal light contamination, as well as a possible cosmic infrared background (CIB). This is done via a re gression analysis of the 100 mu m DIRBE map against the Leiden-Dwingel oo map of H I emission, with corrections for the zodiacal light via a suitable expansion of the DIRBE 25 mu m flux. This procedure removes v irtually all traces of the zodiacal foreground. For the 100 mu m map n o significant CIB is detected. At longer wavelengths, where the zodiac al contamination is weaker, we detect the CIB at surprisingly high flu x levels of 32 +/- 13 nW m(-2) sr(-1) at 140 mu m and of 17 +/- 4 nW m (-2) sr(-1) at 240 mu m (95% confidence). This integrated flux similar to 2 times that extrapolated from optical galaxies in the Hubble Deep Field. The primary use of these maps is likely to be as a new estimat or of Galactic extinction. To calibrate our maps, we assume a standard reddening law and use the colors of elliptical galaxies to measure th e reddening per unit flux density of 100 mu m emission. We find consis tent calibration using the B-R color distribution of a sample of the 1 06 brightest cluster ellipticals, as well as a sample of 384 elliptica ls with B-V and Mg line strength measurements. For the latter sample, we use the correlation of intrinsic B-V versus Mg, index to tighten th e power of the test greatly. We demonstrate that the new maps are twic e as accurate as the older Burstein-Heiles reddening estimates in regi ons of low and moderate reddening. The maps are expected to be signifi cantly more accurate in regions of high reddening. These dust maps wil l also be useful for estimating millimeter emission that contaminates cosmic microwave background radiation experiments and for estimating s oft X-ray absorption. We describe how to access our maps readily for g eneral use.