Revised planet brightness temperatures using the Planck /LFI 2018 data release

Aims. We present new estimates of the brightness temperatures of Jupiter, Saturn, Uranus, and Neptune based on the measurements carried in 2009-2013 by Planck/LFI at 30, 44, and 70 GHz and released to the public in 2018. This work extends the results presented in the 2013 and 2015 Planck/LFI Calibration Papers, based on the data acquired in 2009-2011. Methods. Planck observed each planet up to eight times during the nominal mission. We processed time-ordered data from the 22 LFI radiometers to derive planet antenna temperatures for each planet and transit. We accounted for the beam shape, radiometer bandpasses, and several systematic effects. We compared our results with the results from the ninth year of WMAP, Planck/HFI observations, and existing data and models for planetary microwave emissivity. Results. For Jupiter, we obtain Tb = 144.9, 159.8, 170.5 K (\ub1 0.2 K at 1\u3c3, with temperatures expressed using the Rayleigh-Jeans scale) at 30, 44 and 70 GHz, respectively, or equivalently a band averaged Planck temperature Tb(ba) = 144.7, 160.3, 171.2 K in good agreement with WMAP and existing models. A slight excess at 30 GHz with respect to models is interpreted as an effect of synchrotron emission. Our measures for Saturn agree with the results from WMAP for rings Tb = 9.2 \ub1 1.4, 12.6 \ub1 2.3, 16.2 \ub1 0.8 K, while for the disc we obtain Tb = 140.0 \ub1 1.4, 147.2 \ub1 1.2, 150.2 \ub1 0.4 K, or equivalently a Tb(ba) = 139.7, 147.8, 151.0 K. Our measures for Uranus (Tb = 152 \ub1 6, 145 \ub1 3, 132.0 \ub1 2 K, or Tb(ba) = 152, 145, 133 K) and Neptune (Tb = 154 \ub1 11, 148 \ub1 9, 128 \ub1 3 K, or Tb(ba) = 154, 149, 128 K) agree closely with WMAP and previous data in literature

A systematic approach to the Planck LFI end-to-end test and its application to the DPC Level 1 pipeline

The Level 1 of the Planck LFI Data Processing Centre (DPC) is devoted to the handling of the scientific and housekeeping telemetry. It is a critical component of the Planck ground segment which has to strictly commit to the project schedule to be ready for the launch and flight operations. In order to guarantee the quality necessary to achieve the objectives of the Planck mission, the design and development of the Level 1 software has followed the ESA Software Engineering Standards. A fundamental step in the software life cycle is the Verification and Validation of the software. The purpose of this work is to show an example of procedures, test development and analysis successfully applied to a key software project of an ESA mission. We present the end-to-end validation tests performed on the Level 1 of the LFI-DPC, by detailing the methods used and the results obtained. Different approaches have been used to test the scientific and housekeeping data processing. Scientific data processing has been tested by injecting signals with known properties directly into the acquisition electronics, in order to generate a test dataset of real telemetry data and reproduce as much as possible nominal conditions. For the HK telemetry processing, validation software have been developed to inject known parameter values into a set of real housekeeping packets and perform a comparison with the corresponding timelines generated by the Level 1. With the proposed validation and verification procedure, where the on-board and ground processing are viewed as a single pipeline, we demonstrated that the scientific and housekeeping processing of the Planck-LFI raw data is correct and meets the project requirements.Comment: 20 pages, 7 figures; this paper is part of the Prelaunch status LFI papers published on JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/jins

Dynamic validation of the Planck/LFI thermal model

The Low Frequency Instrument (LFI) is an array of cryogenically cooled radiometers on board the Planck satellite, designed to measure the temperature and polarization anisotropies of the cosmic microwave backgrond (CMB) at 30, 44 and 70 GHz. The thermal requirements of the LFI, and in particular the stringent limits to acceptable thermal fluctuations in the 20 K focal plane, are a critical element to achieve the instrument scientific performance. Thermal tests were carried out as part of the on-ground calibration campaign at various stages of instrument integration. In this paper we describe the results and analysis of the tests on the LFI flight model (FM) performed at Thales Laboratories in Milan (Italy) during 2006, with the purpose of experimentally sampling the thermal transfer functions and consequently validating the numerical thermal model describing the dynamic response of the LFI focal plane. This model has been used extensively to assess the ability of LFI to achieve its scientific goals: its validation is therefore extremely important in the context of the Planck mission. Our analysis shows that the measured thermal properties of the instrument show a thermal damping level better than predicted, therefore further reducing the expected systematic effect induced in the LFI maps. We then propose an explanation of the increased damping in terms of non-ideal thermal contacts.Comment: Planck LFI technical papers published by JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/1748-022

Effect of Fourier filters in removing periodic systematic effects from CMB data

We consider the application of high-pass Fourier filters to remove periodic systematic fluctuations from full-sky survey CMB datasets. We compare the filter performance with destriping codes commonly used to remove the effect of residual 1/f noise from timelines. As a realistic working case, we use simulations of the typical Planck scanning strategy and Planck Low Frequency Instrument noise performance, with spurious periodic fluctuations that mimic a typical thermal disturbance. We show that the application of Fourier high-pass filters in chunks always requires subsequent normalisation of induced offsets by means of destriping. For a complex signal containing all the astrophysical and instrumental components, the result obtained by applying filter and destriping in series is comparable to the result obtained by destriping only, which makes the usefulness of Fourier filters questionable for removing this kind of effects.Comment: 10 pages, 8 figures, published in Astronomy & Astrophysic

Optimization of Planck/LFI on--board data handling

To asses stability against 1/f noise, the Low Frequency Instrument (LFI) onboard the Planck mission will acquire data at a rate much higher than the data rate allowed by its telemetry bandwith of 35.5 kbps. The data are processed by an onboard pipeline, followed onground by a reversing step. This paper illustrates the LFI scientific onboard processing to fit the allowed datarate. This is a lossy process tuned by using a set of 5 parameters Naver, r1, r2, q, O for each of the 44 LFI detectors. The paper quantifies the level of distortion introduced by the onboard processing, EpsilonQ, as a function of these parameters. It describes the method of optimizing the onboard processing chain. The tuning procedure is based on a optimization algorithm applied to unprocessed and uncompressed raw data provided either by simulations, prelaunch tests or data taken from LFI operating in diagnostic mode. All the needed optimization steps are performed by an automated tool, OCA2, which ends with optimized parameters and produces a set of statistical indicators, among them the compression rate Cr and EpsilonQ. For Planck/LFI the requirements are Cr = 2.4 and EpsilonQ <= 10% of the rms of the instrumental white noise. To speedup the process an analytical model is developed that is able to extract most of the relevant information on EpsilonQ and Cr as a function of the signal statistics and the processing parameters. This model will be of interest for the instrument data analysis. The method was applied during ground tests when the instrument was operating in conditions representative of flight. Optimized parameters were obtained and the performance has been verified, the required data rate of 35.5 Kbps has been achieved while keeping EpsilonQ at a level of 3.8% of white noise rms well within the requirements.Comment: 51 pages, 13 fig.s, 3 tables, pdflatex, needs JINST.csl, graphicx, txfonts, rotating; Issue 1.0 10 nov 2009; Sub. to JINST 23Jun09, Accepted 10Nov09, Pub.: 29Dec09; This is a preprint, not the final versio

Advanced modelling of the Planck-LFI radiometers

The Low Frequency Instrument (LFI) is a radiometer array covering the 30-70 GHz spectral range on-board the ESA Planck satellite, launched on May 14th, 2009 to observe the cosmic microwave background (CMB) with unprecedented precision. In this paper we describe the development and validation of a software model of the LFI pseudo-correlation receivers which enables to reproduce and predict all the main system parameters of interest as measured at each of the 44 LFI detectors. These include system total gain, noise temperature, band-pass response, non-linear response. The LFI Advanced RF Model (LARFM) has been constructed by using commercial software tools and data of each radiometer component as measured at single unit level. The LARFM has been successfully used to reproduce the LFI behavior observed during the LFI ground-test campaign. The model is an essential element in the database of LFI data processing center and will be available for any detailed study of radiometer behaviour during the survey.Comment: 21 pages, 15 figures, this paper is part of the Prelaunch status LFI papers published on JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/jins

Off-line radiometric analysis of Planck/LFI data

The Planck Low Frequency Instrument (LFI) is an array of 22 pseudo-correlation radiometers on-board the Planck satellite to measure temperature and polarization anisotropies in the Cosmic Microwave Background (CMB) in three frequency bands (30, 44 and 70 GHz). To calibrate and verify the performances of the LFI, a software suite named LIFE has been developed. Its aims are to provide a common platform to use for analyzing the results of the tests performed on the single components of the instrument (RCAs, Radiometric Chain Assemblies) and on the integrated Radiometric Array Assembly (RAA). Moreover, its analysis tools are designed to be used during the flight as well to produce periodic reports on the status of the instrument. The LIFE suite has been developed using a multi-layered, cross-platform approach. It implements a number of analysis modules written in RSI IDL, each accessing the data through a portable and heavily optimized library of functions written in C and C++. One of the most important features of LIFE is its ability to run the same data analysis codes both using ground test data and real flight data as input. The LIFE software suite has been successfully used during the RCA/RAA tests and the Planck Integrated System Tests. Moreover, the software has also passed the verification for its in-flight use during the System Operations Verification Tests, held in October 2008.Comment: Planck LFI technical papers published by JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/1748-022

Planck-LFI: Design and Performance of the 4 Kelvin Reference Load Unit

The LFI radiometers use a pseudo-correlation design where the signal from the sky is continuously compared with a stable reference signal, provided by a cryogenic reference load system. The reference unit is composed by small pyramidal horns, one for each radiometer, 22 in total, facing small absorbing targets, made of a commercial resin ECCOSORB CR (TM), cooled to approximately 4.5 K. Horns and targets are separated by a small gap to allow thermal decoupling. Target and horn design is optimized for each of the LFI bands, centered at 70, 44 and 30 GHz. Pyramidal horns are either machined inside the radiometer 20K module or connected via external electro-formed bended waveguides. The requirement of high stability of the reference signal imposed a careful design for the radiometric and thermal properties of the loads. Materials used for the manufacturing have been characterized for thermal, RF and mechanical properties. We describe in this paper the design and the performance of the reference system.Comment: This is an author-created, un-copyedited version of an article accepted for publication in JINST. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at [10.1088/1748-0221/4/12/T12006]. 14 pages, 34 figure

ESPRESSO: The next European exoplanet hunter

The acronym ESPRESSO stems for Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations; this instrument will be the next VLT high resolution spectrograph. The spectrograph will be installed at the Combined-Coud\'e Laboratory of the VLT and linked to the four 8.2 m Unit Telescopes (UT) through four optical Coud\'e trains. ESPRESSO will combine efficiency and extreme spectroscopic precision. ESPRESSO is foreseen to achieve a gain of two magnitudes with respect to its predecessor HARPS, and to improve the instrumental radial-velocity precision to reach the 10 cm/s level. It can be operated either with a single UT or with up to four UTs, enabling an additional gain in the latter mode. The incoherent combination of four telescopes and the extreme precision requirements called for many innovative design solutions while ensuring the technical heritage of the successful HARPS experience. ESPRESSO will allow to explore new frontiers in most domains of astrophysics that require precision and sensitivity. The main scientific drivers are the search and characterization of rocky exoplanets in the habitable zone of quiet, nearby G to M-dwarfs and the analysis of the variability of fundamental physical constants. The project passed the final design review in May 2013 and entered the manufacturing phase. ESPRESSO will be installed at the Paranal Observatory in 2016 and its operation is planned to start by the end of the same year.Comment: 12 pages, figures included, accepted for publication in Astron. Nach

Planck-LFI radiometers' spectral response

The Low Frequency Instrument (LFI) is an array of pseudo-correlation radiometers on board the Planck satellite, the ESA mission dedicated to precision measurements of the Cosmic Microwave Background. The LFI covers three bands centred at 30, 44 and 70 GHz, with a goal bandwidth of 20% of the central frequency. The characterization of the broadband frequency response of each radiometer is necessary to understand and correct for systematic effects, particularly those related to foreground residuals and polarization measurements. In this paper we present the measured band shape of all the LFI channels and discuss the methods adopted for their estimation. The spectral characterization of each radiometer was obtained by combining the measured spectral response of individual units through a dedicated RF model of the LFI receiver scheme. As a consistency check, we also attempted end-to-end spectral measurements of the integrated radiometer chain in a cryogenic chamber. However, due to systematic effects in the measurement setup, only qualitative results were obtained from these tests. The measured LFI bandpasses exhibit a moderate level of ripple, compatible with the instrument scientific requirements.Comment: 16 pages, 9 figures, this paper is part of the Prelaunch status LFI papers published on JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/jins