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 | +13.7199 | -4.891 |
| 2020-03-20 | 2020-04-12 | -22.9046 | +3.035 |
| 2020-04-12 | 2020-04-27 | -8.4918 | +0.541 |
| 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) |
|---|---|---|---|---|
| 2026-03-26 00:00 | 07:03:32.96 | +11:00:58.7 | HIP 34033 | 4.07 |
| 2026-03-26 12:00 | 07:03:32.08 | +11:01:22.8 | HIP 34033 | 4.52 |
| 2026-03-27 00:00 | 07:03:31.27 | +11:01:46.9 | HIP 34033 | 4.96 |
| 2026-03-27 12:00 | 07:03:30.51 | +11:02:10.8 | HIP 34033 | 5.40 |
| 2026-03-28 00:00 | 07:03:29.81 | +11:02:34.7 | HIP 34033 | 5.83 |
| 2026-03-28 12:00 | 07:03:29.17 | +11:02:58.4 | HIP 34033 | 6.26 |
| 2026-03-29 00:00 | 07:03:28.58 | +11:03:22.1 | HIP 34033 | 6.68 |
| 2026-03-29 12:00 | 07:03:28.06 | +11:03:45.6 | HIP 34033 | 7.09 |
| 2026-03-30 00:00 | 07:03:27.59 | +11:04:09.1 | HIP 34033 | 7.50 |
| 2026-03-30 12:00 | 07:03:27.18 | +11:04:32.4 | HIP 34033 | 7.90 |
| 2026-03-31 00:00 | 07:03:26.83 | +11:04:55.6 | HIP 34033 | 8.29 |
| 2026-03-31 12:00 | 07:03:26.54 | +11:05:18.8 | HIP 34033 | 8.68 |
| 2026-04-01 00:00 | 07:03:26.31 | +11:05:41.8 | HIP 34033 | 9.06 |
| 2026-04-01 12:00 | 07:03:26.13 | +11:06:04.7 | HIP 34033 | 9.43 |
| 2026-04-02 00:00 | 07:03:26.01 | +11:06:27.5 | HIP 34033 | 9.81 |
| 2026-04-02 12:00 | 07:03:25.95 | +11:06:50.2 | HIP 34033 | 10.17 |
| 2026-04-03 00:00 | 07:03:25.95 | +11:07:12.8 | HIP 34033 | 10.53 |
| 2026-04-03 12:00 | 07:03:26.00 | +11:07:35.3 | HIP 34033 | 10.89 |
| 2026-04-04 00:00 | 07:03:26.11 | +11:07:57.6 | HIP 34033 | 11.24 |
| 2026-04-04 12:00 | 07:03:26.28 | +11:08:19.8 | HIP 34033 | 11.59 |
| 2026-04-05 00:00 | 07:03:26.51 | +11:08:42.0 | HIP 34033 | 11.93 |
| 2026-04-05 12:00 | 07:03:26.79 | +11:09:04.0 | HIP 34033 | 12.27 |
| 2026-04-06 00:00 | 07:03:27.13 | +11:09:25.9 | HIP 34033 | 12.61 |
| 2026-04-06 12:00 | 07:03:27.53 | +11:09:47.6 | HIP 34033 | 12.94 |
| 2026-04-07 00:00 | 07:03:27.98 | +11:10:09.3 | HIP 34033 | 13.28 |
| 2026-04-07 12:00 | 07:03:28.49 | +11:10:30.8 | HIP 34033 | 13.61 |
| 2026-04-08 00:00 | 07:03:29.06 | +11:10:52.2 | HIP 34033 | 13.94 |
| 2026-04-08 12:00 | 07:03:29.68 | +11:11:13.4 | HIP 34033 | 14.26 |
| 2026-04-09 00:00 | 07:03:30.36 | +11:11:34.6 | HIP 34033 | 14.59 |
| 2026-04-09 12:00 | 07:03:31.10 | +11:11:55.6 | HIP 34033 | 14.91 |
| 2026-04-10 00:00 | 07:03:31.89 | +11:12:16.5 | HIP 34033 | 15.24 |
| 2026-04-10 12:00 | 07:03:32.74 | +11:12:37.2 | HIP 34033 | 15.57 |
| 2026-04-11 00:00 | 07:03:33.64 | +11:12:57.9 | HIP 34033 | 15.89 |
| 2026-04-11 12:00 | 07:03:34.60 | +11:13:18.4 | HIP 34033 | 16.22 |
| 2026-04-12 00:00 | 07:03:35.61 | +11:13:38.7 | HIP 34033 | 16.55 |
| 2026-04-12 12:00 | 07:03:36.68 | +11:13:58.9 | HIP 34033 | 16.88 |
| 2026-04-13 00:00 | 07:03:37.81 | +11:14:19.0 | HIP 34033 | 17.21 |
| 2026-04-13 12:00 | 07:03:38.99 | +11:14:39.0 | HIP 34033 | 17.54 |
| 2026-04-14 00:00 | 07:03:40.22 | +11:14:58.8 | HIP 34033 | 17.88 |
| 2026-04-14 12:00 | 07:03:41.51 | +11:15:18.5 | HIP 34033 | 18.22 |
| 2026-04-15 00:00 | 07:03:42.85 | +11:15:38.0 | HIP 34033 | 18.56 |
| 2026-04-15 12:00 | 07:03:44.25 | +11:15:57.4 | HIP 34033 | 18.91 |
| 2026-04-16 00:00 | 07:03:45.71 | +11:16:16.7 | HIP 34033 | 19.26 |