C/2019 T4 (ATLAS)
| 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 |
+6.6977 |
-5.781 |
| 2021-02-02 |
2022-06-06 |
-0.8622 |
+0.131 |
| 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) |
| 2026-02-03 00:00 |
19:19:46.10 |
+28:06:44.7 |
HIP 95033 |
13.15 |
| 2026-02-03 12:00 |
19:20:00.00 |
+28:07:57.1 |
HIP 95033 |
13.49 |
| 2026-02-04 00:00 |
19:20:13.86 |
+28:09:10.2 |
HIP 95033 |
14.61 |
| 2026-02-04 12:00 |
19:20:27.68 |
+28:10:24.2 |
HIP 95033 |
16.33 |
| 2026-02-05 00:00 |
19:20:41.45 |
+28:11:38.9 |
HIP 95033 |
18.49 |
| 2026-02-05 12:00 |
19:20:55.18 |
+28:12:54.4 |
HIP 95012 |
20.50 |
| 2026-02-06 00:00 |
19:21:08.86 |
+28:14:10.8 |
HIP 95012 |
21.53 |
| 2026-02-06 12:00 |
19:21:22.49 |
+28:15:27.9 |
HIP 95012 |
22.96 |
| 2026-02-07 00:00 |
19:21:36.08 |
+28:16:45.8 |
HIP 95187 |
23.40 |
| 2026-02-07 12:00 |
19:21:49.62 |
+28:18:04.4 |
HIP 95187 |
21.86 |
| 2026-02-08 00:00 |
19:22:03.12 |
+28:19:23.9 |
HIP 95187 |
20.71 |
| 2026-02-08 12:00 |
19:22:16.56 |
+28:20:44.1 |
HIP 95187 |
20.01 |
| 2026-02-09 00:00 |
19:22:29.96 |
+28:22:05.1 |
HIP 95187 |
19.81 |
| 2026-02-09 12:00 |
19:22:43.31 |
+28:23:26.9 |
HIP 95365 |
19.80 |
| 2026-02-10 00:00 |
19:22:56.60 |
+28:24:49.4 |
HIP 95365 |
17.97 |
| 2026-02-10 12:00 |
19:23:09.85 |
+28:26:12.6 |
HIP 95365 |
16.58 |
| 2026-02-11 00:00 |
19:23:23.05 |
+28:27:36.7 |
HIP 95397 |
14.77 |
| 2026-02-11 12:00 |
19:23:36.19 |
+28:29:01.4 |
HIP 95397 |
11.56 |
| 2026-02-12 00:00 |
19:23:49.28 |
+28:30:26.9 |
HIP 95397 |
8.36 |
| 2026-02-12 12:00 |
19:24:02.31 |
+28:31:53.2 |
HIP 95397 |
5.17 |
| 2026-02-13 00:00 |
19:24:15.30 |
+28:33:20.2 |
HIP 95397 |
2.04 |
| 2026-02-13 12:00 |
19:24:28.23 |
+28:34:47.9 |
HIP 95397 |
1.42 |
| 2026-02-14 00:00 |
19:24:41.10 |
+28:36:16.3 |
HIP 95397 |
4.49 |
| 2026-02-14 12:00 |
19:24:53.92 |
+28:37:45.5 |
HIP 95397 |
7.65 |
| 2026-02-15 00:00 |
19:25:06.68 |
+28:39:15.4 |
HIP 95397 |
10.81 |
| 2026-02-15 12:00 |
19:25:19.38 |
+28:40:46.0 |
HIP 95521 |
7.90 |
| 2026-02-16 00:00 |
19:25:32.03 |
+28:42:17.3 |
HIP 95521 |
4.80 |
| 2026-02-16 12:00 |
19:25:44.62 |
+28:43:49.3 |
HIP 95521 |
1.90 |
| 2026-02-17 00:00 |
19:25:57.15 |
+28:45:21.9 |
HIP 95521 |
2.02 |
| 2026-02-17 12:00 |
19:26:09.62 |
+28:46:55.3 |
HIP 95521 |
4.93 |
| 2026-02-18 00:00 |
19:26:22.03 |
+28:48:29.4 |
HIP 95521 |
8.01 |
| 2026-02-18 12:00 |
19:26:34.39 |
+28:50:04.1 |
HIP 95521 |
11.12 |
| 2026-02-19 00:00 |
19:26:46.68 |
+28:51:39.6 |
HIP 95521 |
14.22 |
| 2026-02-19 12:00 |
19:26:58.90 |
+28:53:15.6 |
HIP 95521 |
17.33 |
| 2026-02-20 00:00 |
19:27:11.07 |
+28:54:52.4 |
HIP 95609 |
20.20 |
| 2026-02-20 12:00 |
19:27:23.17 |
+28:56:29.8 |
HIP 95609 |
19.62 |
| 2026-02-21 00:00 |
19:27:35.21 |
+28:58:07.9 |
HIP 95609 |
19.51 |
| 2026-02-21 12:00 |
19:27:47.19 |
+28:59:46.6 |
HIP 95797 |
17.48 |
| 2026-02-22 00:00 |
19:27:59.10 |
+29:01:25.9 |
HIP 95797 |
14.77 |
| 2026-02-22 12:00 |
19:28:10.95 |
+29:03:05.9 |
HIP 95797 |
12.26 |
| 2026-02-23 00:00 |
19:28:22.73 |
+29:04:46.4 |
HIP 95797 |
10.08 |
| 2026-02-23 12:00 |
19:28:34.44 |
+29:06:27.7 |
HIP 95797 |
8.51 |
| 2026-02-24 00:00 |
19:28:46.09 |
+29:08:09.5 |
HIP 95797 |
7.88 |