ISOCAM observations in the Lockman Hole^*,**,***

I. The 14.3 μm shallow survey: Data reduction, catalogue, and optical identifications

¹ Spitzer Science Center, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91126, USA e-mail: fadda@ipac.caltech.edu
² Instituto de Astrofísica de Canarias (IAC), via Lactea S/N, 38200 La Laguna, Spain
³ Istituto di Radioastronomia del CNR (IRA), via Gobetti 101, 40129 Bologna, Italy
⁴ Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
⁵ CEA, DSM, DAPNIA, Service d'Astrophysique, 91191 Gif-sur-Yvette Cedex, France
⁶ European Southern Observatory (ESO), Karl-Schwarzschild-Strasse, 2, 85748 Garching bei München, Germany

Received: 6 May 2004
Accepted: 2 July 2004

Abstract

We present the image and catalogue of the 14.3 μm shallow survey of 0.55 square degrees in the region of the Lockman Hole (10^h52^m03^s+57^o21′46″, J2000) with the Infrared Space Observatory (ISO). The data have been analyzed with the recent algorithm by Lari et al. ([CITE], MNRAS, 325, 1173) conceived to exploit ISO data in an optimal way, especially in the case of shallow surveys with low redundancy. Photometry has been accurately evaluated through extensive simulations and also the absolute calibration has been checked using a set of 21 stars detected at 14.3 μm, optical, and near-IR bands. On the basis of simulations, we evaluate that the survey is 80%, 50%, and 20% complete at 0.8, 0.6, and 0.45 mJy, respectively. Below the 20% completeness limit, fluxes are generally overestimated since the sources are preferentially detected if their positions correspond to positive oscillations of the noise. Moreover, from a comparison with the deep survey, we estimate that only sources brighter than 0.45 mJy are highly reliable. Only 5% of these sources do not have optical counterparts down to . Since none of the Spitzer imaging bands cover the 14.3 μm wavelength range, this data set will remain unique until the advent of the James Webb Space Telescope.