Planckearly results. IV. First assessment of the High Frequency Instrument in-flight performance

Abstract

The Planck High Frequency Instrument (HFI) is designed to measure the temperature and polarization anisotropies of the cosmic microwave background and Galactic foregrounds in six ∼30% bands centered at 100, 143, 217, 353, 545, and 857 GHz at an angular resolution of 10 (100 GHz), 7 (143 GHz), and 5 (217 GHz and higher). HFI has been operating flawlessly since launch on 14 May 2009, with the bolometers reaching 100 mK the first week of July. The settings of the readout electronics, including bolometer bias currents, that optimize HFI's noise performance on orbit are nearly the same as the ones chosen during ground testing. Observations of Mars, Jupiter, and Saturn have confirmed that the optical beams and the time responses of the detection chains are in good agreement with the predictions of physical optics modeling and pre-launch measurements. The Detectors suffer from a high flux of cosmic rays due to historically low levels of solar activity. As a result of the redundancy of Planck's observation strategy, the removal of a few percent of data contaminated by glitches does not significantly affect the instrumental sensitivity. The cosmic ray flux represents a significant and variable heat load on the sub-Kelvin stage. Temporal variation and the inhomogeneous distribution of the flux results in thermal fluctuations that are a probable source of low frequency noise. The removal of systematic effects in the time ordered data provides a signal with an average noise equivalent power that is 70% of the goal in the 0.6−2.5 Hz range. This is slightly higher than was achieved during the pre-launch characterization but better than predicted in the early phases of the project. The improvement over the goal is a result of the low level of instrumental background loading achieved by the optical and thermal design of the HFI.

Cloud Structure of Three Galactic Infrared Dark Star-forming Regions from Combining Ground- and Space-based Bolometric Observations

“…For our combination purpose, we use the Herschel SPIRE extended emission products from the data base. The Planck353 GHz images, which are in units of K CMB ,are converted to Jy beam −1 (Planck HFI Core Team et al 2011aTeam et al , 2011bZacchei et al 2011). …”

Transition-edge sensor detectors for the Origins Space Telescope

“…Even with template fitting of its radiometric data, a science data loss of ∼10 − 15% was experienced due to these "glitch"-like temporal events. 96,97 Beyond impacting observational efficiency, nonideal detector responses associated with these energetic events can lead to instrumental stability and calibration issues, which reduce imaging fidelity if unmitigated. Origins will require higher sensitivity and, by extension, a lower focal plane operating temperature than used in previously deployed systems and thus increase the relative importance of the sensor's thermal bus implementation on minimizing the impact of cosmic rays.…”

The Planck Cold Clump G108.37-01.06: A Site of Complex Interplay between H ii Regions, Young Clusters, and Filaments

“…Planck: The Planck satellite surveyed the entire sky in nine frequency wavebands during 2009(Planck Collaboration et al 2011a) with the High Frequency Instrument (HFI;857,545,353,217,143 and 100 GHz) impacting the effective angular resolution ranging from 5 ′ to 9.6 ′ (Lamarre et al 2010;Planck HFI Core Team et al 2011).…”