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Table 1.
Systematic effects and noise components in LOFAR observations.
| Effect | Type of | Phase or | Frequency | Direction | Time |
|---|---|---|---|---|---|
| Jones matrix | Amplitude? | dependence | dependent? | dependent? | |
| Clock drift | Scalar | Phase | ∝ν | ✗ | ✓(minutes) |
| Polarization alignment | Diagonal | Phase | ∝ν | ✗ | ✗ |
| Ionosphere 1st ord. (dispersive delay) | Scalar | Phase | ∝ν−1 | ✓ | ✓(seconds) |
| Ionosphere 2nd ord. (Faraday rotation) | Rotation | Both | ∝ν−2 | ✓ | ✓(seconds) |
| Ionosphere 3rd ord. | Scalar | Phase | ∝ν−3 | ✓ | ✓(seconds) |
| Ionosphere scintillations | Diagonal | Amplitude | – | ✓ | ✓(seconds) |
| Dipole beam | Full-Jones | Both | Complex | ✓ | ✓(minutes) |
| Array factor | Scalar | Both | Complex | ✓ | ✓(minutes) |
| Bandpass | Diagonal | Amplitude | Complex | ✗ | ✗ |
| Sky noise | Additive | Both | ∝ν−2.57(a) | ✓ | ✓(random) |
| Instrumental noise | Additive | Both | Complex | ✗ | ✓(random) |
Notes. This table is an extended version of the one in de Gasperin et al. (2019) and contains the noise components discussed in van Haarlem et al. (2013).
(a)
Sky noise spectral index from Guzmán et al. (2011) and valid for the North Galactic Pole.
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