Table 2
Summary of the astrometric calibration model and number of calibration parameters in the astrometric solution for Gaia EDR3.
| Basis functions | Multiplicity of dependencies | Number of | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Effect (i) and brief description |  |
Klm | j | f | n | g | b | w | νeff | G | S | ϕ | Δt |  |
parameters | |
| 1 | AL large-scale geometric | lm = 00, 10, 20, 01 | 4 | 310 | 2 | 62 | – | – | 4 | – | – | – | – | – | – | 615 040 |
| 2 | AL medium-scale gate | lm = 00, 10 | 2 | 19 | 2 | 62 | 8 | 9 | – | – | – | – | – | – | – | 339 264 |
| 3 | AL large-scale colour | lm = 00, 01 | 2 | 19 | 2 | 62 | – | – | 4 | 1 | – | – | – | – | – | 18 848 |
| 4 | AL large-scale saturation | lm = 00 | 1 | 19 | 2 | 62 | – | – | 2 | – | – | 1 | – | – | – | 4 712 |
| 5 | AL large-scale subpixel | lm = 00 | 1 | 19 | 2 | 62 | – | – | 4 | – | – | – | 2 | – | – | 18 848 |
| 6 | AL large-scale CTI | lm = 00 | 1 | 19 | 2 | 62 | – | – | 4 | – | – | – | – | 4 | – | 37 696 |
| 7 | AL large-scale AC rate | lm = 00 | 1 | 19 | 2 | 62 | – | – | 1 | – | – | – | – | – | 1 | 2 356 |
| 8 | AC large-scale geometric | lm = 00, 10, 20, 01 | 4 | 19 | 2 | 62 | – | – | 2 | – | – | – | – | – | – | 18 848 |
| 9 | AC large-scale gate | lm = 00 | 1 | 19 | 2 | 62 | 8 | – | – | – | – | – | – | – | – | 18 848 |
| 10 | AC large-scale colour | lm = 00 | 1 | 19 | 2 | 62 | – | – | 2 | 1 | – | – | – | – | – | 4 712 |
| 11 | AC large-scale magnitude | lm = 00 | 1 | 19 | 2 | 62 | – | – | 2 | – | 1 | – | – | – | – | 4 712 |
| 12 | AC large-scale saturation | lm = 00 | 1 | 19 | 2 | 62 | – | – | 2 | – | – | 1 | – | – | – | 4 712 |
Notes. The column Basis functions lists the combinations of indices l and m used to model variations with AC coordinate on a CCD (
) and with time within a time granule (
). Multiplicity of dependencies gives the number of distinct functions or values for each dependency, or a dash if there is no dependency: basis functions (Klm , Eq. (5)), granuleindex (j), field index (f), CCD index (n), gate (g), stitch block (b), window class (w), effective wavenumber (νeff ), magnitude (G), saturation (S), subpixel phase (ϕ), time since last charge injection (Δt), and AC scan rate (
). The last column is the product of multiplicities, equal to the number of calibration parameters for the effect. The SMs are not considered here.
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