### 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.Original language | English |
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Article number | A5 |

Number of pages | 19 |

Journal | Astronomy and Astrophysics |

Volume | 536 |

DOIs | |

Publication status | Published - 2011 |

MoE publication type | A1 Journal article-refereed |

### Keywords

- methods: data analysis
- cosmic backround radiation
- cosmology: observations
- surveys

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## Cite this

Zacchei, A., Tuovinen, J., & Planck Collaboration (2011). Planck early results. V: The Low Frequency Instrument data processing.

*Astronomy and Astrophysics*,*536*, [A5]. https://doi.org/10.1051/0004-6361/201116484