Multiwavelength Study of the NEPR Sample. The 60µm Luminosity Function Paola Mazzei 1 , Daniela Bettoni 1 , Antonio Della Valle 1,3 , Herv´ e Aussel 2 , Gianfranco De Zotti 1 , and Alberto Franceschini 3 1 INAF, Osservatorio Astronomico, Vicolo dell’Osservatorio 5, 35122 Padova, Italy 2 University of Hawaii, USA 3 Universit´a di Padova,Vicolo dell’Osservatorio 6, 35122 Padova, Italy Abstract. We present the 60µm luminosity function (LF) of the deepest complete IRAS selected sample [1] so far available, in the North Ecliptic Polar Region (NEPR). The LF here is the first step in the multi-wavelength study of this sample which, thanks to our ISOCAM observations, provides a direct link between IRAS and ISOCAM sur- veys and the forthcoming deeper SIRTF cosmological surveys. The sample is unique in allowing a direct investigation of the evolution of the global Spectral Energy Dis- tribution (SED) of dusty galaxies up to a redshift of about 0.3, where the global star formation rate is known to evolve very fast. 1 Redshift Distribution and 60 µm LF The IRAS Deep Survey (IDS) sample was defined by Hacking and Houck [1] co-adding IRAS scans of the North Ecliptic Polar Region (NEPR), representing more than 20 hours of integration time. It comprises 98 galaxies with S(60 µm)> 50 mJy over an area of 6.25 sq. deg. and is still the deepest complete and sta- tistically significant 60 µm selected sample available before the advent of the SIRTF observatory; for comparison the deepest ISOPHOT surveys, FIRBACK at 175µm [2], ELAIS and Lookman Hole at 90 µm, [3], [4], are all complete at 100 mJy. The IDS sample is also superior to those in the coverage of the SED of its member galaxies. In fact, in addition to 60 µm fluxes, most of them have also 100 µm fluxes and several have 25 µm fluxes. VLA observations for a good fraction of sample sources have been made by [5]. Moreover we have obtained ISOCAM observations in the LW3 filter (range 12-18 µm) of 94 of these sources [6]. Our spectroscopy runs at the TNG, Keck II, Subaru and Asiago telescopes, from 1999 to 2002, have yielded redshifts for all the optical counterparts of our ISOCAM sources, the best candidates of the IRAS sources. The data by [7], who measured the redshifts of 76 tentative optical counterparts of IDS sources, turned out indeed to be not the correct identifications, based on our ISOCAM positions. The redshift distribution of our sample is shown in Fig. 1 (left panel). Two sub-clusters, at z=0.055 and 0.080, are visible. IRAS fluxes at ISOCAM positions have been recently revised [8] showing that our sample is complete for S(60 µm)> 80mJy. Our derived 60 µm LF, in Fig. 1 (right panel), is in good agreement with previous estimates [9]. Optical imaging has been planned for the whole sample; B, R and Ks images ESO Symposia: Multiwavelength Mapping of Galaxy Evolution and Formation, pp. 424–425, 2005. © Springer-Verlag Berlin Heidelberg 2005