| 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) |
| 2026-03-26 00:00 |
19:38:06.15 |
+31:04:55.9 |
HIP 96618 |
10.78 |
| 2026-03-26 12:00 |
19:38:12.88 |
+31:07:03.5 |
HIP 96618 |
8.23 |
| 2026-03-27 00:00 |
19:38:19.52 |
+31:09:11.3 |
HIP 96618 |
5.71 |
| 2026-03-27 12:00 |
19:38:26.07 |
+31:11:19.2 |
HIP 96618 |
3.27 |
| 2026-03-28 00:00 |
19:38:32.52 |
+31:13:27.4 |
HIP 96618 |
1.36 |
| 2026-03-28 12:00 |
19:38:38.88 |
+31:15:35.7 |
HIP 96618 |
2.44 |
| 2026-03-29 00:00 |
19:38:45.15 |
+31:17:44.2 |
HIP 96618 |
4.78 |
| 2026-03-29 12:00 |
19:38:51.32 |
+31:19:52.8 |
HIP 96618 |
7.24 |
| 2026-03-30 00:00 |
19:38:57.39 |
+31:22:01.6 |
HIP 96618 |
9.73 |
| 2026-03-30 12:00 |
19:39:03.38 |
+31:24:10.6 |
HIP 96618 |
12.21 |
| 2026-03-31 00:00 |
19:39:09.26 |
+31:26:19.7 |
HIP 96618 |
14.70 |
| 2026-03-31 12:00 |
19:39:15.05 |
+31:28:28.9 |
HIP 96618 |
17.18 |
| 2026-04-01 00:00 |
19:39:20.75 |
+31:30:38.2 |
HIP 96804 |
18.23 |
| 2026-04-01 12:00 |
19:39:26.34 |
+31:32:47.7 |
HIP 96804 |
18.01 |
| 2026-04-02 00:00 |
19:39:31.84 |
+31:34:57.3 |
HIP 96804 |
18.14 |
| 2026-04-02 12:00 |
19:39:37.25 |
+31:37:06.9 |
HIP 96804 |
18.62 |
| 2026-04-03 00:00 |
19:39:42.56 |
+31:39:16.7 |
HIP 96602 |
19.04 |
| 2026-04-03 12:00 |
19:39:47.77 |
+31:41:26.5 |
HIP 96850 |
18.77 |
| 2026-04-04 00:00 |
19:39:52.88 |
+31:43:36.5 |
HIP 96850 |
18.59 |
| 2026-04-04 12:00 |
19:39:57.90 |
+31:45:46.5 |
HIP 96850 |
18.73 |
| 2026-04-05 00:00 |
19:40:02.82 |
+31:47:56.6 |
HIP 96850 |
19.20 |
| 2026-04-05 12:00 |
19:40:07.64 |
+31:50:06.7 |
HIP 96850 |
19.97 |
| 2026-04-06 00:00 |
19:40:12.36 |
+31:52:16.9 |
HIP 96850 |
21.00 |
| 2026-04-06 12:00 |
19:40:16.98 |
+31:54:27.1 |
HIP 96850 |
22.25 |
| 2026-04-07 00:00 |
19:40:21.50 |
+31:56:37.3 |
HIP 96850 |
23.69 |
| 2026-04-07 12:00 |
19:40:25.93 |
+31:58:47.6 |
HIP 96850 |
25.27 |
| 2026-04-08 00:00 |
19:40:30.25 |
+32:00:57.9 |
HIP 96850 |
26.98 |
| 2026-04-08 12:00 |
19:40:34.48 |
+32:03:08.2 |
HIP 96850 |
28.79 |
| 2026-04-09 00:00 |
19:40:38.60 |
+32:05:18.5 |
HIP 96850 |
30.67 |
| 2026-04-09 12:00 |
19:40:42.63 |
+32:07:28.8 |
HIP 96836 |
29.77 |
| 2026-04-10 00:00 |
19:40:46.55 |
+32:09:39.1 |
HIP 96836 |
27.53 |
| 2026-04-10 12:00 |
19:40:50.37 |
+32:11:49.3 |
HIP 96836 |
25.31 |
| 2026-04-11 00:00 |
19:40:54.09 |
+32:13:59.5 |
HIP 96836 |
23.11 |
| 2026-04-11 12:00 |
19:40:57.71 |
+32:16:09.7 |
HIP 96836 |
20.93 |
| 2026-04-12 00:00 |
19:41:01.23 |
+32:18:19.8 |
HIP 96836 |
18.79 |
| 2026-04-12 12:00 |
19:41:04.65 |
+32:20:29.9 |
HIP 96836 |
16.68 |
| 2026-04-13 00:00 |
19:41:07.97 |
+32:22:39.9 |
HIP 96836 |
14.61 |
| 2026-04-13 12:00 |
19:41:11.18 |
+32:24:49.8 |
HIP 96836 |
12.62 |
| 2026-04-14 00:00 |
19:41:14.29 |
+32:26:59.7 |
HIP 96836 |
10.74 |
| 2026-04-14 12:00 |
19:41:17.30 |
+32:29:09.4 |
HIP 96836 |
9.02 |
| 2026-04-15 00:00 |
19:41:20.20 |
+32:31:19.1 |
HIP 96836 |
7.57 |
| 2026-04-15 12:00 |
19:41:23.01 |
+32:33:28.6 |
HIP 96836 |
6.56 |
| 2026-04-16 00:00 |
19:41:25.71 |
+32:35:38.0 |
HIP 96836 |
6.22 |