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) |
|---|---|---|---|---|
| 2026-05-12 00:00 | 07:06:09.74 | +11:29:21.2 | HIP 34189 | 16.13 |
| 2026-05-12 12:00 | 07:06:13.70 | +11:29:31.9 | HIP 34189 | 16.95 |
| 2026-05-13 00:00 | 07:06:17.70 | +11:29:42.3 | HIP 34231 | 17.79 |
| 2026-05-13 12:00 | 07:06:21.74 | +11:29:52.6 | HIP 34231 | 18.37 |
| 2026-05-14 00:00 | 07:06:25.82 | +11:30:02.7 | HIP 34231 | 18.98 |
| 2026-05-14 12:00 | 07:06:29.93 | +11:30:12.7 | HIP 34231 | 19.63 |
| 2026-05-15 00:00 | 07:06:34.09 | +11:30:22.4 | HIP 34231 | 20.32 |
| 2026-05-15 12:00 | 07:06:38.28 | +11:30:32.0 | HIP 34231 | 21.03 |
| 2026-05-16 00:00 | 07:06:42.51 | +11:30:41.4 | HIP 34231 | 21.78 |
| 2026-05-16 12:00 | 07:06:46.78 | +11:30:50.6 | HIP 34231 | 22.55 |
| 2026-05-17 00:00 | 07:06:51.09 | +11:30:59.6 | HIP 34231 | 23.35 |
| 2026-05-17 12:00 | 07:06:55.43 | +11:31:08.5 | HIP 34231 | 24.17 |
| 2026-05-18 00:00 | 07:06:59.81 | +11:31:17.1 | HIP 34231 | 25.02 |
| 2026-05-18 12:00 | 07:07:04.23 | +11:31:25.6 | HIP 34231 | 25.89 |
| 2026-05-19 00:00 | 07:07:08.68 | +11:31:33.9 | HIP 34231 | 26.78 |
| 2026-05-19 12:00 | 07:07:13.17 | +11:31:42.1 | HIP 34231 | 27.69 |
| 2026-05-20 00:00 | 07:07:17.69 | +11:31:50.0 | HIP 34231 | 28.61 |
| 2026-05-20 12:00 | 07:07:22.25 | +11:31:57.8 | HIP 34231 | 29.56 |
| 2026-05-21 00:00 | 07:07:26.84 | +11:32:05.3 | HIP 34231 | 30.52 |
| 2026-05-21 12:00 | 07:07:31.47 | +11:32:12.7 | HIP 34231 | 31.50 |
| 2026-05-22 00:00 | 07:07:36.13 | +11:32:20.0 | HIP 34231 | 32.49 |
| 2026-05-22 12:00 | 07:07:40.82 | +11:32:27.0 | HIP 34231 | 33.50 |
| 2026-05-23 00:00 | 07:07:45.55 | +11:32:33.8 | HIP 34549 | 34.07 |
| 2026-05-23 12:00 | 07:07:50.30 | +11:32:40.5 | HIP 34549 | 33.14 |
| 2026-05-24 00:00 | 07:07:55.09 | +11:32:47.0 | HIP 34549 | 32.23 |
| 2026-05-24 12:00 | 07:07:59.92 | +11:32:53.3 | HIP 34549 | 31.34 |
| 2026-05-25 00:00 | 07:08:04.77 | +11:32:59.4 | HIP 34549 | 30.46 |
| 2026-05-25 12:00 | 07:08:09.65 | +11:33:05.4 | HIP 34549 | 29.60 |
| 2026-05-26 00:00 | 07:08:14.57 | +11:33:11.1 | HIP 34549 | 28.76 |
| 2026-05-26 12:00 | 07:08:19.52 | +11:33:16.7 | HIP 34549 | 27.94 |
| 2026-05-27 00:00 | 07:08:24.49 | +11:33:22.1 | HIP 34549 | 27.16 |
| 2026-05-27 12:00 | 07:08:29.50 | +11:33:27.3 | HIP 34549 | 26.40 |
| 2026-05-28 00:00 | 07:08:34.53 | +11:33:32.4 | HIP 34549 | 25.68 |
| 2026-05-28 12:00 | 07:08:39.60 | +11:33:37.2 | HIP 34549 | 25.01 |
| 2026-05-29 00:00 | 07:08:44.69 | +11:33:41.9 | HIP 34549 | 24.37 |
| 2026-05-29 12:00 | 07:08:49.81 | +11:33:46.4 | HIP 34549 | 23.79 |
| 2026-05-30 00:00 | 07:08:54.96 | +11:33:50.7 | HIP 34549 | 23.25 |
| 2026-05-30 12:00 | 07:09:00.14 | +11:33:54.8 | HIP 34549 | 22.78 |
| 2026-05-31 00:00 | 07:09:05.34 | +11:33:58.8 | HIP 34549 | 22.37 |
| 2026-05-31 12:00 | 07:09:10.57 | +11:34:02.6 | HIP 34549 | 22.03 |
| 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 |