| Parameter |
Value |
| Designation |
C/2021 S4 (Tsuchinshan) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2024-01-02T08:26:27.882240Z |
| Orbit solution date (soln_date, UTC) |
2026-03-07T14:42:53Z |
| Obs used |
1156 |
| NEO |
- |
| M1 |
6.400 |
| K1 |
9.250 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2021-09-29T18:31:15.744000Z |
| Discovery magnitude (MPC) |
20.50 R |
| Discovery observatory (MPC) |
D29 · Purple Mountain Observatory, XuYi Station |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2023-10-25.0000000 |
| e |
0.95933247 |
| q (au) |
6.689317 |
| a (au) |
164.487891 |
| i (deg) |
17.478939 |
| Ω (om, deg) |
5.490839 |
| ω (w, deg) |
72.870717 |
| M (ma, deg) |
359.967599 |
Magnitude
Scatter + Global Linear
$$
M_a = (0.703 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
0.703 |
| n |
6.000 |
| gf |
0.892 |
| gb |
-0.917 |
| k |
1.000 |
| δ90 |
5.113 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
09:03:47.98 |
+32:09:25.4 |
HIP 44574 |
19.38 |
| 2026-03-26 12:00 |
09:03:44.30 |
+32:08:32.9 |
HIP 44574 |
20.55 |
| 2026-03-27 00:00 |
09:03:40.75 |
+32:07:39.8 |
HIP 44574 |
21.70 |
| 2026-03-27 12:00 |
09:03:37.33 |
+32:06:46.0 |
HIP 44574 |
22.84 |
| 2026-03-28 00:00 |
09:03:34.03 |
+32:05:51.6 |
HIP 44574 |
23.98 |
| 2026-03-28 12:00 |
09:03:30.85 |
+32:04:56.6 |
HIP 44574 |
25.10 |
| 2026-03-29 00:00 |
09:03:27.80 |
+32:04:01.0 |
HIP 44574 |
26.21 |
| 2026-03-29 12:00 |
09:03:24.88 |
+32:03:04.8 |
HIP 44574 |
27.31 |
| 2026-03-30 00:00 |
09:03:22.08 |
+32:02:08.0 |
HIP 44307 |
28.15 |
| 2026-03-30 12:00 |
09:03:19.41 |
+32:01:10.5 |
HIP 44307 |
28.12 |
| 2026-03-31 00:00 |
09:03:16.87 |
+32:00:12.5 |
HIP 44307 |
28.15 |
| 2026-03-31 12:00 |
09:03:14.45 |
+31:59:13.9 |
HIP 44307 |
28.26 |
| 2026-04-01 00:00 |
09:03:12.16 |
+31:58:14.7 |
HIP 44307 |
28.44 |
| 2026-04-01 12:00 |
09:03:10.00 |
+31:57:14.9 |
HIP 44307 |
28.68 |
| 2026-04-02 00:00 |
09:03:07.96 |
+31:56:14.5 |
HIP 44307 |
28.99 |
| 2026-04-02 12:00 |
09:03:06.05 |
+31:55:13.6 |
HIP 44307 |
29.37 |
| 2026-04-03 00:00 |
09:03:04.27 |
+31:54:12.1 |
HIP 44307 |
29.80 |
| 2026-04-03 12:00 |
09:03:02.61 |
+31:53:10.0 |
HIP 44307 |
30.30 |
| 2026-04-04 00:00 |
09:03:01.08 |
+31:52:07.4 |
HIP 44401 |
30.51 |
| 2026-04-04 12:00 |
09:02:59.68 |
+31:51:04.3 |
HIP 44401 |
29.42 |
| 2026-04-05 00:00 |
09:02:58.41 |
+31:50:00.5 |
HIP 44401 |
28.34 |
| 2026-04-05 12:00 |
09:02:57.27 |
+31:48:56.3 |
HIP 44401 |
27.24 |
| 2026-04-06 00:00 |
09:02:56.25 |
+31:47:51.5 |
HIP 44401 |
26.14 |
| 2026-04-06 12:00 |
09:02:55.36 |
+31:46:46.1 |
HIP 44401 |
25.04 |
| 2026-04-07 00:00 |
09:02:54.60 |
+31:45:40.2 |
HIP 44401 |
23.93 |
| 2026-04-07 12:00 |
09:02:53.96 |
+31:44:33.8 |
HIP 44401 |
22.82 |
| 2026-04-08 00:00 |
09:02:53.46 |
+31:43:26.9 |
HIP 44401 |
21.70 |
| 2026-04-08 12:00 |
09:02:53.08 |
+31:42:19.4 |
HIP 44401 |
20.57 |
| 2026-04-09 00:00 |
09:02:52.83 |
+31:41:11.5 |
HIP 44401 |
19.44 |
| 2026-04-09 12:00 |
09:02:52.71 |
+31:40:03.0 |
HIP 44401 |
18.30 |
| 2026-04-10 00:00 |
09:02:52.72 |
+31:38:54.0 |
HIP 44401 |
17.16 |
| 2026-04-10 12:00 |
09:02:52.85 |
+31:37:44.5 |
HIP 44401 |
16.02 |
| 2026-04-11 00:00 |
09:02:53.11 |
+31:36:34.5 |
HIP 44401 |
14.87 |
| 2026-04-11 12:00 |
09:02:53.50 |
+31:35:24.0 |
HIP 44401 |
13.73 |
| 2026-04-12 00:00 |
09:02:54.02 |
+31:34:13.0 |
HIP 44401 |
12.59 |
| 2026-04-12 12:00 |
09:02:54.67 |
+31:33:01.6 |
HIP 44401 |
11.46 |
| 2026-04-13 00:00 |
09:02:55.44 |
+31:31:49.6 |
HIP 44401 |
10.34 |
| 2026-04-13 12:00 |
09:02:56.35 |
+31:30:37.2 |
HIP 44401 |
9.25 |
| 2026-04-14 00:00 |
09:02:57.37 |
+31:29:24.3 |
HIP 44401 |
8.20 |
| 2026-04-14 12:00 |
09:02:58.53 |
+31:28:10.9 |
HIP 44401 |
7.21 |
| 2026-04-15 00:00 |
09:02:59.82 |
+31:26:57.1 |
HIP 44401 |
6.32 |
| 2026-04-15 12:00 |
09:03:01.23 |
+31:25:42.8 |
HIP 44401 |
5.60 |
| 2026-04-16 00:00 |
09:03:02.77 |
+31:24:28.0 |
HIP 44401 |
5.12 |