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Making maps from Planck LFI 30 GHz data with asymmetric beams and cooler noise

Ashdown, M. A. J.  and Baccigalupi, C. and Bartlett, J. G. and Borrill, J. and Cantalupo, C. and De Gasperis, G. and De Troia, G. and Górski, K. M. and Hivon, E. and Huffenberger, K. and Keihänen, E. and Keskitalo, R. and Kisner, T. and Kurki-Suonio, H. and Lawrence, C. R. and Natoli, P. and Poutanen, T. and Prézeau, G. and Reinecke, M. and Rocha, G. and Sandri, M. and Stompor, R. and Villa, F. and Wandelt, B. (2009) Making maps from Planck LFI 30 GHz data with asymmetric beams and cooler noise. Astronomy and Astrophysics, 493 (2). pp. 753-783. ISSN 0004-6361.

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The PLANCK satellite will observe the full sky at nine frequencies from 30 to 857 GHz. Temperature and polarization frequency maps made from these observations are prime deliverables of the PLANCK mission. The goal of this paper is to examine the effects of four realistic instrument systematics in the 30 GHz frequency maps: non-axially-symmetric beams, sample integration, sorption cooler noise, and pointing errors. We simulated one-year long observations of four 30 GHz detectors. The simulated timestreams contained cosmic microwave background (CMB) signal, foreground components (both galactic and extra-galactic), instrument noise (correlated and white), and the four instrument systematic effects. We made maps from the timelines and examined the magnitudes of the systematics effects in the maps and their angular power spectra. We also compared the maps of different mapmaking codes to see how they performed. We used five mapmaking codes (two destripers and three optimal codes). None of our mapmaking codes makes any attempt to deconvolve the beam from its output map. Therefore all our maps had similar smoothing due to beams and sample integration. This is a complicated smoothing, because each map pixel has its own effective beam. Temperature to polarization cross-coupling due to beam mismatch causes a detectable bias in the TE spectrum of the CMB map. The effects of cooler noise and pointing errors did not appear to be major concerns for the 30 GHz channel. The only essential difference found so far between mapmaking codes that affects accuracy (in terms of residual root-mean-square) is baseline length. All optimal codes give essentially indistinguishable results. A destriper gives the same result as the optimal codes when the baseline is set short enough (Madam). For longer baselines destripers (Springtide and Madam) require less computing resources but deliver a noisier map.

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Rocha, G.0000-0002-4150-8076
Additional Information:© ESO 2009. Received 13 June 2008 / Accepted 3 November 2008. The work reported in this paper was done by the CTP Working Group of the Planck Consortia. Planck is a mission of the European Space Agency. The authors would like to thank Osservatorio Astronomico di Trieste (OAT) for its hospitality in May 2006 when the CTP Working Group met to undertake this work. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DEAC03- 76SF00098. We acknowledge the use of version 1.1 of the Planck sky model, prepared by the members of Planck Working Group 2, available at (CMB and extra- Galactic emission), and (Galactic emission). We acknowledge the use of the CAMB ( code for generating theoretical CMB spectra. We thank Anna-Stiina Sirviö for help with CAMB. The authors thank Aniello Mennella for providing the sorption cooler data. This work has made use of the Planck satellite simulation package (Level-S), which is assembled by the Max Planck Institute for Astrophysics Planck Analysis Centre (MPAC). This work has been partially supported by Agenzia Spaziale Italiana under ASI contract Planck LFI Activity of Phase E2 and by the NASA LTSA Grant NNG04CG90G. This work was supported in part by the Academy of Finland grants 205800, 214598, 121703, and 121962. R.K. is supported by the Jenny and Antti Wihuri Foundation. H.K.S. and T.P. thank Waldemar von Frenckells stiftelse, H.K.S. and T.P. thank Magnus Ehrnrooth Foundation, and E.K. and T.P. thank Väisälä Foundation for financial support. Some of the results in this paper have been derived using the HEALPix package (Górski et al. 2005a). The US Planck Project is supported by the NASA Science Mission Directorate.
Funding AgencyGrant Number
Office of Science of the U.S. Department of EnergyDEAC03-76SF00098
Agenzia Spaziale Italiana under ASI contract Planck LFI Activity of Phase E2UNSPECIFIED
Academy of Finland205800
Academy of Finland214598
Academy of Finland121703
Academy of Finland121962
Jenny and Antti Wihuri FoundationUNSPECIFIED
Magnus Ehrnrooth FoundationUNSPECIFIED
Väisälä FoundatioUNSPECIFIED
Issue or Number:2
Record Number:CaltechAUTHORS:20090623-105423341
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14429
Deposited By: Tony Diaz
Deposited On:25 Jun 2009 20:36
Last Modified:09 Mar 2020 13:19

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