A classical approach to faint extragalactic source extraction from ISOCAM deep surveys. Application to the Hubble Deep Field

摘要

We have developed a general data reduction technique for ISOCAM data comingfrom various deep surveys of faint galaxies. In order to reach the fundamentallimits of the camera (due to the background photon noise and the readoutnoise), we have devised several steps in the reduction processes that transformthe raw data to a sky map which is then used for point source and sligthlyextended source extraction. We show illustrative examples of our present schemeby using data taken from the publicly available Hubble Deep Field ISOCAM surveyin order to demonstrate its characteristics. More than thirty sources down tothe 60 (resp. 100) microJy level are clearly detected above 4 sigma atwavelengths of 7 (resp. 15) micron, the vast majority at 15 micron. A largefraction of these sources can be identified with visible objects of medianmagnitude 22 and K-band magnitude of 17.5 and redshifts between 0.5 and 1 (whenavailable). A few very red objects could be at larger redshifts.