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Table 17
List of known instrumental systematic effects in Planck-LFI.
| Effect | Source | Control/removal |
|
|
||
| Effects independent of sky signal (T and P) | ||
| White noise correlation | Phase switch imbalance | Diode weighting |
| 1/f noise | RF amplifiers | Pseudo-correlation and destriping |
| Bias fluctuations | RF amplifiers, back-end electronics | Pseudo-correlation and destriping |
| Thermal fluctuations | 4-K, 20-K and 300-K thermal stages | Calibration, destriping |
| 1-Hz spikes | Back-end electronics | Template fitting and removal |
| Effects dependent on the sky signal (T and P) | ||
| Main beam ellipticity | Main beams | Accounted for in window function |
| Near sidelobe | Optical response at angles | Masking of Galaxy and point |
| pickup | <5° from the main beam | sources |
| Far sidelobe pickup | Main and sub-reflector spillover | Model sidelobes removed from timelines |
| Analogue-to-digital | Back-end analogue-to-digital | Template fitting and removal |
| converter non-linearity | converter | |
| Imperfect photometric | Sidelobe pickup, radiometer noise | Adaptive smoothing algorithm using 4π |
| calibration | temperature changes and other | beam, 4-K reference load voltage output |
| non-idealities | temperature sensor data | |
| Pointing | Uncertainties in pointing reconstru- | Negligible impact on anisotropy |
| ction, thermal changes affecting | measurements | |
| focal plane geometry | ||
| Effects specifically impacting polarization | ||
| Bandpass asymmetries | Differential orthomode transducer | Spurious polarization removal |
| and receiver bandpass response | ||
| Polarization angle | Uncertainty in the polarization | Negligible impact |
| uncertainty | angle in-flight measurement | |
| Orthomode transducer | Imperfect polarization separation | Negligible impact |
| cross-polarization | ||
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