Sroll2

From Planck Legacy Archive Wiki
Revision as of 16:31, 19 January 2023 by Mlopezca (talk | contribs)
Jump to: navigation, search

Sroll2[edit]

Overview and background[edit]

Sroll2 is an improved mapmaking approach with respect to the one used for the Planck High Frequency Instrument 2018 Legacy release. The algorithm SRoll2 better corrects the known instrumental effects that still affected mostly the polarized large-angular-scale data by distorting the signal, and/or leaving residuals observable in null tests. The main systematic effect is the nonlinear response of the onboard analog-to-digital convertors that was cleaned in the Planck HFI Legacy release as an empirical time-varying linear detector chain response which is the first-order effect. The SRoll2 method fits the model parameters for higher-order effects and corrects the full distortion of the signal. The model parameters are fitted using the redundancies in the data by iteratively comparing the data and a model. The polarization efficiency uncertainties and associated errors have also been corrected based on the redundancies in the data and their residual levels characterized with simulations.

SRoll2: an improved mapmaking approach to reduce large-scale systematic effects in the Planck High Frequency Instrument legacy maps (Delouis et al., A&A 609, A38, 2019), A&A

Data Description[edit]

Data set description

The SRoll 2.0 data set is made of 28 FITS files each containing the I, Q and U Stokes parameters of a single frequency, multi-bolometer, full-sky observation in KCMB, as well as its hit count and covariance matrix elements (II, IQ, IU, QQ, QU, UU, in KCMB2). These maps are generated using only the 8 polarised HFI bolometers ("PSB") of each polarised HFI frequency (100 GHz, 143 GHz, 217 GHz and 353 GHz) to obtain the best possible polarised maps. The maps are stored in HEALPix format at Nside=2,048 (50,331,648 pixels per map). They are named and formatted in the same way as the Planck HFI 2018 products (see the Planck Legacy Archive (PLA)):

  • SRoll20 is the data product name and version,
  • SkyMap is the signal type, here all sky components,
  • the detector set, made of the detectors frequency (100, 143, 217, 353), followed by the detectors used in the map (psb for all 8 bolometers, ds1 for the first 4 bolometers, ds2 for the last 4 bolometers)
  • the ring set, either full for all the rings of the mission (240-26050), or halfmission-1 (rings 240-13144), halfmission-2 (rings 13145-26050), or even or odd numbered rings (full-even or full-odd, respectively).


(Planck) High Frequency Instrument

Flexible Image Transfer Specification

(Hierarchical Equal Area isoLatitude Pixelation of a sphere, <ref name="Template:Gorski2005">HEALPix: A Framework for High-Resolution Discretization and Fast Analysis of Data Distributed on the Sphere, K. M. Górski, E. Hivon, A. J. Banday, B. D. Wandelt, F. K. Hansen, M. Reinecke, M. Bartelmann, ApJ, 622, 759-771, (2005).

Planck Legacy Archive

Retrieved from ‘https://wiki.cosmos.esa.int/planck-legacy-archive/index.php?title=Sroll2&oldid=14620’