C/2019 Y4 (ATLAS)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2019 Y4 (ATLAS) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2020-05-31T00:23:50.930880Z |
| Orbit solution date (soln_date, UTC) | 2024-01-05T08:08:32Z |
| Obs used | 1259 |
| NEO | - |
| M1 | 8.800 |
| K1 | 18.500 |
| PC | 0.030 |
| Discovery observation (MPC, UTC) | 2019-12-28T14:19:26.457600Z |
| Discovery magnitude (MPC) | 19.63 o |
| Discovery observatory (MPC) | T08 · ATLAS-MLO, Mauna Loa |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2020-02-24.0000000 |
| e | 0.99922493 |
| q (au) | 0.252854 |
| a (au) | 326.234163 |
| i (deg) | 45.380208 |
| Ω (om, deg) | 120.568599 |
| ω (w, deg) | 177.409813 |
| M (ma, deg) | 359.983772 |
Magnitude
Scatter + Global Linear
$$ M_a = (9.706 + 5.131\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 9.706 |
| n | 5.131 |
| gf | 0.800 |
| gb | -0.500 |
| k | 1.000 |
| δ90 | 1.000 |
| Parameter | Symbol | Range | Description |
|---|---|---|---|
| Absolute magnitude at 1 AU from Sun and Earth | H0 | -5 to 20 | Intrinsic brightness of the comet |
| Photometric slope parameter | n | 2 to 6 | Rate of brightness change with heliocentric distance |
| Forward scattering asymmetry factor | gf |
0.8 to 1 | Degree of forward scattering |
| Backward scattering asymmetry factor | gb |
-1 to -0.5 | Degree of backward scattering |
| Partitioning coefficient | k | 0.8 to 1 | Ratio between forward/backward scattering contributions |
| Dust-to-gas brightness ratio | δ90 | 1 to 10 | Relative contribution of dust scattering to gas emission |
Reference: EPSC-DPS2025-160
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) | End (UTC) | a | b |
|---|---|---|---|
| 2019-12-20 | 2020-03-20 | +13.7200 | -4.891 |
| 2020-03-20 | 2020-04-12 | -22.9056 | +3.035 |
| 2020-04-12 | 2020-04-27 | -8.4908 | +0.540 |
| 2020-04-27 | 2020-05-21 | -11.1661 | +1.086 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-06-01 00:00 | 07:09:15.83 | +11:34:06.2 | HIP 34549 | 21.76 |
| 2026-06-01 12:00 | 07:09:21.11 | +11:34:09.6 | HIP 34549 | 21.56 |
| 2026-06-02 00:00 | 07:09:26.42 | +11:34:12.8 | HIP 34549 | 21.45 |
| 2026-06-02 12:00 | 07:09:31.76 | +11:34:15.9 | HIP 34549 | 21.42 |
| 2026-06-03 00:00 | 07:09:37.12 | +11:34:18.7 | HIP 34549 | 21.47 |
| 2026-06-03 12:00 | 07:09:42.51 | +11:34:21.4 | HIP 34549 | 21.60 |
| 2026-06-04 00:00 | 07:09:47.92 | +11:34:23.9 | HIP 34549 | 21.82 |
| 2026-06-04 12:00 | 07:09:53.35 | +11:34:26.3 | HIP 34549 | 22.12 |
| 2026-06-05 00:00 | 07:09:58.81 | +11:34:28.4 | HIP 34549 | 22.50 |
| 2026-06-05 12:00 | 07:10:04.30 | +11:34:30.4 | HIP 34549 | 22.95 |
| 2026-06-06 00:00 | 07:10:09.80 | +11:34:32.2 | HIP 34549 | 23.48 |
| 2026-06-06 12:00 | 07:10:15.33 | +11:34:33.8 | HIP 34549 | 24.08 |
| 2026-06-07 00:00 | 07:10:20.89 | +11:34:35.2 | HIP 34549 | 24.75 |
| 2026-06-07 12:00 | 07:10:26.46 | +11:34:36.5 | HIP 34549 | 25.47 |
| 2026-06-08 00:00 | 07:10:32.06 | +11:34:37.5 | HIP 34549 | 26.25 |
| 2026-06-08 12:00 | 07:10:37.68 | +11:34:38.4 | HIP 34549 | 27.09 |
| 2026-06-09 00:00 | 07:10:43.32 | +11:34:39.1 | HIP 34549 | 27.97 |
| 2026-06-09 12:00 | 07:10:48.98 | +11:34:39.7 | HIP 34549 | 28.90 |
| 2026-06-10 00:00 | 07:10:54.66 | +11:34:40.0 | HIP 34549 | 29.87 |
| 2026-06-10 12:00 | 07:11:00.36 | +11:34:40.2 | HIP 34549 | 30.87 |
| 2026-06-11 00:00 | 07:11:06.08 | +11:34:40.2 | HIP 34549 | 31.91 |
| 2026-06-11 12:00 | 07:11:11.83 | +11:34:40.0 | HIP 34549 | 32.99 |
| 2026-06-12 00:00 | 07:11:17.59 | +11:34:39.6 | HIP 34549 | 34.09 |
| 2026-06-12 12:00 | 07:11:23.37 | +11:34:39.1 | HIP 34549 | 35.22 |
| 2026-06-13 00:00 | 07:11:29.17 | +11:34:38.4 | HIP 34549 | 36.38 |
| 2026-06-13 12:00 | 07:11:34.99 | +11:34:37.5 | HIP 34549 | 37.56 |
| 2026-06-14 00:00 | 07:11:40.82 | +11:34:36.4 | HIP 34960 | 38.51 |
| 2026-06-14 12:00 | 07:11:46.67 | +11:34:35.1 | HIP 34960 | 37.24 |
| 2026-06-15 00:00 | 07:11:52.54 | +11:34:33.7 | HIP 34960 | 35.99 |
| 2026-06-15 12:00 | 07:11:58.43 | +11:34:32.1 | HIP 34960 | 34.76 |
| 2026-06-16 00:00 | 07:12:04.33 | +11:34:30.3 | HIP 34960 | 33.53 |
| 2026-06-16 12:00 | 07:12:10.25 | +11:34:28.3 | HIP 34960 | 32.33 |
| 2026-06-17 00:00 | 07:12:16.18 | +11:34:26.2 | HIP 34960 | 31.14 |
| 2026-06-17 12:00 | 07:12:22.13 | +11:34:23.9 | HIP 34960 | 29.97 |
| 2026-06-18 00:00 | 07:12:28.09 | +11:34:21.4 | HIP 34960 | 28.83 |
| 2026-06-18 12:00 | 07:12:34.07 | +11:34:18.7 | HIP 34960 | 27.72 |
| 2026-06-19 00:00 | 07:12:40.06 | +11:34:15.9 | HIP 34960 | 26.64 |
| 2026-06-19 12:00 | 07:12:46.06 | +11:34:12.9 | HIP 34960 | 25.61 |
| 2026-06-20 00:00 | 07:12:52.08 | +11:34:09.7 | HIP 34960 | 24.61 |
| 2026-06-20 12:00 | 07:12:58.11 | +11:34:06.3 | HIP 34960 | 23.67 |
| 2026-06-21 00:00 | 07:13:04.15 | +11:34:02.8 | HIP 34960 | 22.78 |
| 2026-06-21 12:00 | 07:13:10.21 | +11:33:59.1 | HIP 34960 | 21.96 |
| 2026-06-22 00:00 | 07:13:16.27 | +11:33:55.2 | HIP 34960 | 21.21 |