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) |
|---|---|---|---|---|
| 2026-07-29 00:00 | 07:20:51.95 | +11:22:00.5 | HIP 35657 | 23.01 |
| 2026-07-29 12:00 | 07:20:57.85 | +11:21:45.8 | HIP 35657 | 22.27 |
| 2026-07-30 00:00 | 07:21:03.74 | +11:21:30.9 | HIP 35657 | 21.60 |
| 2026-07-30 12:00 | 07:21:09.62 | +11:21:16.0 | HIP 35657 | 21.02 |
| 2026-07-31 00:00 | 07:21:15.48 | +11:21:01.0 | HIP 35657 | 20.52 |
| 2026-07-31 12:00 | 07:21:21.32 | +11:20:45.8 | HIP 35657 | 20.11 |
| 2026-08-01 00:00 | 07:21:27.15 | +11:20:30.6 | HIP 35657 | 19.80 |
| 2026-08-01 12:00 | 07:21:32.95 | +11:20:15.2 | HIP 35657 | 19.59 |
| 2026-08-02 00:00 | 07:21:38.75 | +11:19:59.7 | HIP 35657 | 19.48 |
| 2026-08-02 12:00 | 07:21:44.52 | +11:19:44.2 | HIP 35657 | 19.48 |
| 2026-08-03 00:00 | 07:21:50.27 | +11:19:28.5 | HIP 35657 | 19.58 |
| 2026-08-03 12:00 | 07:21:56.01 | +11:19:12.7 | HIP 35657 | 19.78 |
| 2026-08-04 00:00 | 07:22:01.73 | +11:18:56.9 | HIP 35657 | 20.08 |
| 2026-08-04 12:00 | 07:22:07.43 | +11:18:40.9 | HIP 35657 | 20.47 |
| 2026-08-05 00:00 | 07:22:13.11 | +11:18:24.8 | HIP 35657 | 20.94 |
| 2026-08-05 12:00 | 07:22:18.76 | +11:18:08.6 | HIP 35657 | 21.50 |
| 2026-08-06 00:00 | 07:22:24.40 | +11:17:52.4 | HIP 35657 | 22.12 |
| 2026-08-06 12:00 | 07:22:30.02 | +11:17:36.0 | HIP 35657 | 22.81 |
| 2026-08-07 00:00 | 07:22:35.62 | +11:17:19.6 | HIP 35657 | 23.57 |
| 2026-08-07 12:00 | 07:22:41.19 | +11:17:03.0 | HIP 35657 | 24.37 |
| 2026-08-08 00:00 | 07:22:46.75 | +11:16:46.4 | HIP 35657 | 25.22 |
| 2026-08-08 12:00 | 07:22:52.28 | +11:16:29.6 | HIP 35657 | 26.11 |
| 2026-08-09 00:00 | 07:22:57.79 | +11:16:12.8 | HIP 35894 | 26.64 |
| 2026-08-09 12:00 | 07:23:03.28 | +11:15:55.9 | HIP 35894 | 25.66 |
| 2026-08-10 00:00 | 07:23:08.74 | +11:15:38.9 | HIP 35894 | 24.71 |
| 2026-08-10 12:00 | 07:23:14.19 | +11:15:21.8 | HIP 35894 | 23.81 |
| 2026-08-11 00:00 | 07:23:19.60 | +11:15:04.6 | HIP 35894 | 22.95 |
| 2026-08-11 12:00 | 07:23:24.99 | +11:14:47.4 | HIP 35894 | 22.15 |
| 2026-08-12 00:00 | 07:23:30.36 | +11:14:30.1 | HIP 35894 | 21.40 |
| 2026-08-12 12:00 | 07:23:35.71 | +11:14:12.6 | HIP 35894 | 20.71 |
| 2026-08-13 00:00 | 07:23:41.02 | +11:13:55.1 | HIP 35894 | 20.09 |
| 2026-08-13 12:00 | 07:23:46.32 | +11:13:37.6 | HIP 35894 | 19.54 |
| 2026-08-14 00:00 | 07:23:51.58 | +11:13:19.9 | HIP 35894 | 19.07 |
| 2026-08-14 12:00 | 07:23:56.82 | +11:13:02.2 | HIP 35894 | 18.68 |
| 2026-08-15 00:00 | 07:24:02.04 | +11:12:44.4 | HIP 35894 | 18.37 |
| 2026-08-15 12:00 | 07:24:07.22 | +11:12:26.5 | HIP 35894 | 18.15 |
| 2026-08-16 00:00 | 07:24:12.38 | +11:12:08.6 | HIP 35894 | 18.02 |
| 2026-08-16 12:00 | 07:24:17.51 | +11:11:50.6 | HIP 35894 | 17.98 |
| 2026-08-17 00:00 | 07:24:22.61 | +11:11:32.5 | HIP 35894 | 18.04 |
| 2026-08-17 12:00 | 07:24:27.69 | +11:11:14.4 | HIP 35894 | 18.18 |
| 2026-08-18 00:00 | 07:24:32.73 | +11:10:56.2 | HIP 35894 | 18.40 |
| 2026-08-18 12:00 | 07:24:37.75 | +11:10:37.9 | HIP 36006 | 18.68 |
| 2026-08-19 00:00 | 07:24:42.74 | +11:10:19.6 | HIP 36006 | 17.85 |