Table 2.
Variance measurements, i.e. 
, for the hard X-ray band (HX), and 
in the UV/optical bands, in units of 10−3 (mJy)2.
| Band | Mrk 509 | NGC 4151 | NGC 2617 | Mrk 142 |
|---|---|---|---|---|
| (E19) | (E17) | (F18) | (C20) | |
| HX | 0.015 ± 0.003 (20, 12, 1.03) | 0.027 ± 0.004 (21, 3, 0.21) | 0.16 ± 0.04 (11, 13, 1.47) | 0.19 ± 0.02 (19, 5.5, 0.6) |
| W2/1928 Å | 38 ± 11 (20, 12, 1.12) | 7 ± 2 (21, 3, 0.27) | 96 ± 42 (10, 13, 1.47) | 1.7 ± 0.4 (17, 6, 0.74) |
| M2/2236 Å | 64 ± 26 (20, 12, 1.2) | 8 ± 3 (21, 3, 0.27) | 80 ± 34 (11, 13, 1.52) | 0.8 ± 0.3 (16, 6, 0.74) |
| W1/2600 Å | 29 ± 17 (20, 12, 1.17) | 10 ± 4 (21, 3, 0.25) | 97 ± 44 (10, 13, 1.5) | 1.3 ± 0.4 (17, 6, 0.74) |
| SU/3467 Å | 57 ± 15 (20, 12, 1.07) | 33 ± 16 (21, 3, 0.25) | 185 ± 84 (10, 13, 1.51) | – |
| u/3540 Å | – | – | – | 0.5 ± 0.2 (30, 6, 0.68) |
| SB/4392 Å | 35 ± 10 (20, 12, 1.06) | 55 ± 16 (21, 3, 0.22) | 67 ± 43 (10, 13, 1.52) | 1.1 ± 0.5 (17, 6, 0.66) |
| g/4770 Å | – | – | – | 0.5 ± 0.1 (29, 6, 0.57) |
| SV/5468 Å | 17 ± 9 (20, 12, 1.11) | 90 ± 150 (5, 12, 0.22) | 32 ± 32 (10, 13, 1.42) | – |
| r/6215 Å | – | – | 9 ± 3 (14, 6, 0.76) | 0.3 ± 0.1 (31, 6, 0.56) |
| i/7545 Å | – | – | 10 ± 4 (15, 6, 0.7) | 0.4 ± 0.1 (30, 6, 0.57) |
| z/8982 Å | – | – | 19 ± 7 (14, 6, 0.73) | – |
Notes. Numbers in the parentheses next to the variance measurements list the number of segments, their duration, Tmax (days), and the average Δt (days) of the light curves. SU, SB, and SV denote the respective Swift bands. Light curves are taken from: Edelson et al. (2019, 2017), Fausnaugh et al. (2018), and Cackett et al. (2020) (E19, E17, F18, and C20, respectively). The number next to each band name indicates the effective wavelength, taken from C20, except for the z band which is taken from F18.
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