Planck early results. V. The Low Frequency Instrument data processing^⋆

¹ Aalto University Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
² Agenzia Spaziale Italiana Science Data Center, c/o ESRIN, via Galileo Galilei, Frascati, Italy
³ Agenzia Spaziale Italiana, Viale Liegi 26, Roma, Italy
⁴ Astroparticule et Cosmologie, CNRS (UMR7164), Université Denis Diderot Paris 7, Bâtiment Condorcet, 10 rue A. Domon et Léonie Duquet, Paris, France
⁵ Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 1710, Australia
⁶ CNR - ISTI, Area della Ricerca, via G. Moruzzi 1, Pisa, Italy
⁷ CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
⁸ California Institute of Technology, Pasadena, California, USA
⁹ Centre of Mathematics for Applications, University of Oslo, Blindern, Oslo, Norway
¹⁰ DTU Space, National Space Institute, Juliane Mariesvej 30, Copenhagen, Denmark
¹¹ Departamento de Física, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo, Spain
¹² Departamento de Matemáticas, Estadística y Computación, Universidad de Cantabria, Avda. de los Castros s/n, Santander, Spain
¹³ Department of Physics & Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia, Canada
¹⁴ Department of Physics and Astronomy, University of Southern California, Los Angeles, California, USA
¹⁵ Department of Physics, Gustaf Hällströmin katu 2a, University of Helsinki, Helsinki, Finland
¹⁶ Department of Physics, University of California, Berkeley, California, USA
¹⁷ Department of Physics, University of California, One Shields Avenue, Davis, California, USA
¹⁸ Department of Physics, University of California, Santa Barbara, California, USA
¹⁹ Department of Physics, University of Oxford, 1 Keble Road, Oxford, UK
²⁰ Dipartimento di Fisica G. Galilei, Università degli Studi di Padova, via Marzolo 8, 35131 Padova, Italy
²¹ Dipartimento di Fisica, Università La Sapienza, P. le A. Moro 2, Roma, Italy
²² Dipartimento di Fisica, Università degli Studi di Milano, via Celoria, 16, Milano, Italy
²³ Dipartimento di Fisica, Università degli Studi di Trieste, via A. Valerio 2, Trieste, Italy
²⁴ Dipartimento di Fisica, Università di Ferrara, via Saragat 1, 44122 Ferrara, Italy
²⁵ Dipartimento di Fisica, Università di Roma Tor Vergata, via della Ricerca Scientifica, 1, Roma, Italy
²⁶ Dipartimento di Matematica, Università di Roma Tor Vergata, via della Ricerca Scientifica, 1, Roma, Italy
²⁷ Dpto. Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
²⁸ European Space Agency, ESAC, Planck Science Office, Camino bajo del Castillo, s/n, Urbanización Villafranca del Castillo, Villanueva de la Cañada, Madrid, Spain
²⁹ European Space Agency, ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
³⁰ Haverford College Astronomy Department, 370 Lancaster Avenue, Haverford, Pennsylvania, USA
³¹ Helsinki Institute of Physics, Gustaf Hällströmin katu 2, University of Helsinki, Helsinki, Finland
³² INAF – Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, Firenze, Italy
³³ INAF – Osservatorio Astrofisico di Catania, via S. Sofia 78, Catania, Italy
³⁴ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, Padova, Italy
³⁵ INAF – Osservatorio Astronomico di Roma, via di Frascati 33, Monte Porzio Catone, Italy
³⁶ INAF – Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, Trieste, Italy
³⁷ INAF/IASF Bologna, via Gobetti 101, Bologna, Italy
³⁸ INAF/IASF Milano, via E. Bassini 15, Milano, Italy
³⁹ INRIA, Laboratoire de Recherche en Informatique, Université Paris-Sud 11, Bâtiment 490, 91405 Orsay Cedex, France
⁴⁰ ISDC Data Centre for Astrophysics, University of Geneva, ch. d’Ecogia 16, Versoix, Switzerland
⁴¹ Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA
⁴² Institut d’Astrophysique Spatiale, CNRS (UMR8617) Université Paris-Sud 11, Bâtiment 121, Orsay, France
⁴³ Institut d’Astrophysique de Paris, CNRS UMR7095, Université Pierre & Marie Curie, 98 bis boulevard Arago, Paris, France
⁴⁴ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
⁴⁵ Institute of Theoretical Astrophysics, University of Oslo, Blindern, Oslo, Norway
⁴⁶ Instituto de Astrofísica de Canarias, C/Vía Láctea s/n, La Laguna, Tenerife, Spain
⁴⁷ Instituto de Física de Cantabria (CSIC-Universidad de Cantabria), Avda. de los Castros s/n, Santander, Spain
⁴⁸ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California, USA
⁴⁹ Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
⁵⁰ LERMA, CNRS, Observatoire de Paris, 61 Avenue de l’Observatoire, Paris, France
⁵¹ Lawrence Berkeley National Laboratory, Berkeley, California, USA
⁵² Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany
⁵³ MilliLab, VTT Technical Research Centre of Finland, Tietotie 3, Espoo, Finland
⁵⁴ SISSA, Astrophysics Sector, via Bonomea 265, 34136 Trieste, Italy
⁵⁵ Space Sciences Laboratory, University of California, Berkeley, California, USA
⁵⁶ Spitzer Science Center, 1200 E. California Blvd., Pasadena, California, USA
⁵⁷ Université de Toulouse, UPS-OMP, IRAP, 31028 Toulouse Cedex 4, France
⁵⁸ Warsaw University Observatory, Aleje Ujazdowskie 4, 00-478 Warszawa, Poland

Received: 9 January 2011
Accepted: 19 July 2011

Abstract

We describe the processing of data from the Low Frequency Instrument (LFI) used in production of the Planck Early Release Compact Source Catalogue (ERCSC). In particular, we discuss the steps involved in reducing the data from telemetry packets to cleaned, calibrated, time-ordered data (TOD) and frequency maps. Data are continuously calibrated using the modulation of the temperature of the cosmic microwave background radiation induced by the motion of the spacecraft. Noise properties are estimated from TOD from which the sky signal has been removed using a generalized least square map-making algorithm. Measured 1/f noise knee-frequencies range from  ~100 mHz at 30 GHz to a few tens of mHz at 70GHz. A destriping code (Madam) is employed to combine radiometric data and pointing information into sky maps, minimizing the variance of correlated noise. Noise covariance matrices required to compute statistical uncertainties on LFI and Planck products are also produced. Main beams are estimated down to the  ≈−10dB level using Jupiter transits, which are also used for geometrical calibration of the focal plane.