BeyondPlanck X. Bandpass and beam leakage corrections. (arXiv:2201.03417v1 [astro-ph.CO])

BeyondPlanck X. Bandpass and beam leakage corrections. (arXiv:2201.03417v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Svalheim_T/0/1/0/all/0/1">T. L. Svalheim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Andersen_K/0/1/0/all/0/1">K. J. Andersen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Aurlien_R/0/1/0/all/0/1">R. Aurlien</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Banerji_R/0/1/0/all/0/1">R. Banerji</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bersanelli_M/0/1/0/all/0/1">M. Bersanelli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bertocco_S/0/1/0/all/0/1">S. Bertocco</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brilenkov_M/0/1/0/all/0/1">M. Brilenkov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carbone_M/0/1/0/all/0/1">M. Carbone</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Colombo_L/0/1/0/all/0/1">L. P. L. Colombo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Eriksen_H/0/1/0/all/0/1">H. K. Eriksen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Foss_M/0/1/0/all/0/1">M. K. Foss</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Franceschet_C/0/1/0/all/0/1">C. Franceschet</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fuskeland_U/0/1/0/all/0/1">U. Fuskeland</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Galeotta_S/0/1/0/all/0/1">S. Galeotta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Galloway_M/0/1/0/all/0/1">M. Galloway</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gerakakis_S/0/1/0/all/0/1">S. Gerakakis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gjerlow_E/0/1/0/all/0/1">E. Gjerløw</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hensley_B/0/1/0/all/0/1">B. Hensley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Herman_D/0/1/0/all/0/1">D. Herman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Iacobellis_M/0/1/0/all/0/1">M. Iacobellis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ieronymaki_M/0/1/0/all/0/1">M. Ieronymaki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ihle_H/0/1/0/all/0/1">H. T. Ihle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jewell_J/0/1/0/all/0/1">J. B. Jewell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Karakci_A/0/1/0/all/0/1">A. Karakci</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Keihanen_E/0/1/0/all/0/1">E. Keihänen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Keskitalo_R/0/1/0/all/0/1">R. Keskitalo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Maggio_G/0/1/0/all/0/1">G. Maggio</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Maino_D/0/1/0/all/0/1">D. Maino</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Maris_M/0/1/0/all/0/1">M. Maris</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Paradiso_S/0/1/0/all/0/1">S. Paradiso</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Partridge_B/0/1/0/all/0/1">B. Partridge</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reinecke_M/0/1/0/all/0/1">M. Reinecke</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Suur_Uski_A/0/1/0/all/0/1">A.-S. Suur-Uski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tavagnacco_D/0/1/0/all/0/1">D. Tavagnacco</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Thommesen_H/0/1/0/all/0/1">H. Thommesen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Watts_D/0/1/0/all/0/1">D. J. Watts</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wehus_I/0/1/0/all/0/1">I. K. Wehus</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zacchei_A/0/1/0/all/0/1">A. Zacchei</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zonca_A/0/1/0/all/0/1">A. Zonca</a>

We discuss the treatment of bandpass and beam leakage corrections in the
Bayesian BeyondPlanck CMB analysis pipeline as applied to the Planck LFI
measurements. As a preparatory step, we first apply three corrections to the
nominal LFI bandpass profiles including removal of a known systematic effect in
the ground measuring equipment at 61 GHz; smoothing of standing wave ripples;
and edge regularization. The main net impact of these modifications is an
overall shift in the 70 GHz bandpass of +0.6 GHz; we argue that any analysis of
LFI data products, either from Planck or BeyondPlanck, should use these new
bandpasses. In addition, we fit a single free bandpass parameter for each
radiometer of the form $Delta_i = Delta_0 + delta_i$, where $Delta_0$
represents an absolute frequency shift per frequency band and $delta_i$ is a
relative shift per detector. The absolute correction is only fitted at 30 GHz
with a full $chi^2$-based likelihood, resulting in a correction of
$Delta_{30}=0.24pm0.03,$GHz. The relative corrections are fitted using a
spurious map approach, fundamentally similar to the method pioneered by the
WMAP team, but without introducing many additional degrees of freedom. All
bandpass parameters are sampled using a standard Metropolis sampler within the
main BeyondPlanck Gibbs chain, and bandpass uncertainties are thus propagated
to all other data products in the analysis. In total, we find that our bandpass
model significantly reduces leakage effects. For beam leakage corrections, we
adopt the official Planck LFI beam estimates without additional degrees of
freedom, and only marginalize over the underlying sky model. We note that this
is the first time leakage from beam mismatch has been included for Planck LFI
maps.

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