| Parameter |
Value |
| Designation |
C/2019 T4 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-06-08T23:44:31.977600Z |
| Orbit solution date (soln_date, UTC) |
2025-09-30T13:39:20Z |
| Obs used |
5476 |
| NEO |
- |
| M1 |
4.400 |
| K1 |
10.250 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2019-10-09T13:58:04.368000Z |
| Discovery magnitude (MPC) |
19.39 c |
| Discovery observatory (MPC) |
T05 · ATLAS-HKO, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2023-02-14.0000000 |
| e |
0.99562110 |
| q (au) |
4.242148 |
| a (au) |
968.770059 |
| i (deg) |
53.632165 |
| Ω (om, deg) |
199.939253 |
| ω (w, deg) |
351.177452 |
| M (ma, deg) |
0.008172 |
Magnitude
Scatter + Global Linear
$$
M_a = (3.119 + 4.200\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
3.119 |
| n |
4.200 |
| gf |
0.989 |
| gb |
-0.743 |
| k |
1.000 |
| δ90 |
10.000 |
| 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 |
| 2019-02-05 |
2021-02-02 |
+6.6976 |
-5.781 |
| 2021-02-02 |
2022-06-06 |
-0.8622 |
+0.130 |
| 2022-06-11 |
2025-10-20 |
+0.0696 |
-0.299 |
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 |
19:21:26.81 |
+35:56:49.0 |
HIP 95184 |
7.10 |
| 2026-07-29 12:00 |
19:21:17.93 |
+35:55:58.5 |
HIP 95184 |
8.91 |
| 2026-07-30 00:00 |
19:21:09.09 |
+35:55:06.8 |
HIP 95184 |
10.79 |
| 2026-07-30 12:00 |
19:21:00.30 |
+35:54:14.2 |
HIP 95184 |
12.70 |
| 2026-07-31 00:00 |
19:20:51.54 |
+35:53:20.5 |
HIP 95184 |
14.64 |
| 2026-07-31 12:00 |
19:20:42.83 |
+35:52:25.7 |
HIP 95184 |
16.60 |
| 2026-08-01 00:00 |
19:20:34.17 |
+35:51:29.9 |
HIP 95184 |
18.56 |
| 2026-08-01 12:00 |
19:20:25.55 |
+35:50:33.1 |
HIP 95000 |
19.37 |
| 2026-08-02 00:00 |
19:20:16.97 |
+35:49:35.2 |
HIP 95000 |
17.90 |
| 2026-08-02 12:00 |
19:20:08.44 |
+35:48:36.4 |
HIP 95000 |
16.53 |
| 2026-08-03 00:00 |
19:19:59.96 |
+35:47:36.5 |
HIP 95000 |
15.29 |
| 2026-08-03 12:00 |
19:19:51.53 |
+35:46:35.6 |
HIP 95000 |
14.19 |
| 2026-08-04 00:00 |
19:19:43.15 |
+35:45:33.7 |
HIP 95000 |
13.29 |
| 2026-08-04 12:00 |
19:19:34.82 |
+35:44:30.8 |
HIP 95000 |
12.61 |
| 2026-08-05 00:00 |
19:19:26.54 |
+35:43:26.9 |
HIP 95000 |
12.21 |
| 2026-08-05 12:00 |
19:19:18.31 |
+35:42:22.1 |
HIP 95000 |
12.11 |
| 2026-08-06 00:00 |
19:19:10.14 |
+35:41:16.2 |
HIP 95000 |
12.32 |
| 2026-08-06 12:00 |
19:19:02.02 |
+35:40:09.4 |
HIP 95000 |
12.81 |
| 2026-08-07 00:00 |
19:18:53.95 |
+35:39:01.6 |
HIP 95000 |
13.57 |
| 2026-08-07 12:00 |
19:18:45.95 |
+35:37:52.9 |
HIP 95000 |
14.54 |
| 2026-08-08 00:00 |
19:18:38.00 |
+35:36:43.2 |
HIP 95000 |
15.69 |
| 2026-08-08 12:00 |
19:18:30.10 |
+35:35:32.5 |
HIP 95000 |
16.99 |
| 2026-08-09 00:00 |
19:18:22.27 |
+35:34:20.9 |
HIP 95000 |
18.39 |
| 2026-08-09 12:00 |
19:18:14.49 |
+35:33:08.4 |
HIP 95000 |
19.89 |
| 2026-08-10 00:00 |
19:18:06.78 |
+35:31:55.0 |
HIP 95000 |
21.45 |
| 2026-08-10 12:00 |
19:17:59.13 |
+35:30:40.6 |
HIP 95000 |
23.07 |
| 2026-08-11 00:00 |
19:17:51.54 |
+35:29:25.3 |
HIP 95000 |
24.73 |
| 2026-08-11 12:00 |
19:17:44.02 |
+35:28:09.2 |
HIP 95000 |
26.43 |
| 2026-08-12 00:00 |
19:17:36.56 |
+35:26:52.1 |
HIP 95000 |
28.16 |
| 2026-08-12 12:00 |
19:17:29.16 |
+35:25:34.1 |
HIP 95000 |
29.91 |
| 2026-08-13 00:00 |
19:17:21.83 |
+35:24:15.3 |
HIP 95000 |
31.68 |
| 2026-08-13 12:00 |
19:17:14.57 |
+35:22:55.6 |
HIP 95000 |
33.47 |
| 2026-08-14 00:00 |
19:17:07.38 |
+35:21:35.0 |
HIP 95000 |
35.27 |
| 2026-08-14 12:00 |
19:17:00.25 |
+35:20:13.6 |
HIP 94566 |
33.30 |
| 2026-08-15 00:00 |
19:16:53.20 |
+35:18:51.3 |
HIP 94566 |
31.34 |
| 2026-08-15 12:00 |
19:16:46.21 |
+35:17:28.2 |
HIP 94566 |
29.39 |
| 2026-08-16 00:00 |
19:16:39.30 |
+35:16:04.3 |
HIP 94566 |
27.45 |
| 2026-08-16 12:00 |
19:16:32.45 |
+35:14:39.6 |
HIP 94566 |
25.52 |
| 2026-08-17 00:00 |
19:16:25.68 |
+35:13:14.0 |
HIP 94566 |
23.60 |
| 2026-08-17 12:00 |
19:16:18.99 |
+35:11:47.7 |
HIP 94566 |
21.71 |
| 2026-08-18 00:00 |
19:16:12.37 |
+35:10:20.5 |
HIP 94566 |
19.84 |
| 2026-08-18 12:00 |
19:16:05.82 |
+35:08:52.6 |
HIP 94566 |
18.00 |
| 2026-08-19 00:00 |
19:15:59.35 |
+35:07:24.0 |
HIP 94566 |
16.20 |