| Parameter |
Value |
| Designation |
C/2025 A3 (Tsuchinshan) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2026-03-15T00:00:11.577600Z |
| Orbit solution date (soln_date, UTC) |
2026-07-06T12:12:24Z |
| Obs used |
105 |
| NEO |
- |
| M1 |
9.100 |
| K1 |
10.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2025-01-05T19:43:38.208000Z |
| Discovery magnitude (MPC) |
19.60 R |
| Discovery observatory (MPC) |
D29 · Purple Mountain Observatory, XuYi Station |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2025-05-01.0000000 |
| e |
0.43164511 |
| q (au) |
5.792453 |
| a (au) |
10.191614 |
| i (deg) |
9.977242 |
| Ω (om, deg) |
322.434038 |
| ω (w, deg) |
222.301220 |
| M (ma, deg) |
350.366880 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.748 + 3.211\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.748 |
| n |
3.211 |
| gf |
1.000 |
| gb |
-1.000 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
12:13:20.17 |
-09:37:03.4 |
HIP 59625 |
7.56 |
| 2026-07-29 12:00 |
12:13:37.63 |
-09:38:40.6 |
HIP 59625 |
7.88 |
| 2026-07-30 00:00 |
12:13:55.19 |
-09:40:18.4 |
HIP 59625 |
10.48 |
| 2026-07-30 12:00 |
12:14:12.83 |
-09:41:56.9 |
HIP 59625 |
14.17 |
| 2026-07-31 00:00 |
12:14:30.55 |
-09:43:36.0 |
HIP 59625 |
18.33 |
| 2026-07-31 12:00 |
12:14:48.36 |
-09:45:15.9 |
HIP 59625 |
22.71 |
| 2026-08-01 00:00 |
12:15:06.26 |
-09:46:56.4 |
HIP 59625 |
27.22 |
| 2026-08-01 12:00 |
12:15:24.24 |
-09:48:37.6 |
HIP 59863 |
23.09 |
| 2026-08-02 00:00 |
12:15:42.30 |
-09:50:19.5 |
HIP 59863 |
18.62 |
| 2026-08-02 12:00 |
12:16:00.44 |
-09:52:02.0 |
HIP 59863 |
14.33 |
| 2026-08-03 00:00 |
12:16:18.67 |
-09:53:45.2 |
HIP 59863 |
10.46 |
| 2026-08-03 12:00 |
12:16:36.98 |
-09:55:29.0 |
HIP 59863 |
7.70 |
| 2026-08-04 00:00 |
12:16:55.38 |
-09:57:13.5 |
HIP 59863 |
7.48 |
| 2026-08-04 12:00 |
12:17:13.85 |
-09:58:58.6 |
HIP 59863 |
10.00 |
| 2026-08-05 00:00 |
12:17:32.40 |
-10:00:44.4 |
HIP 59863 |
13.86 |
| 2026-08-05 12:00 |
12:17:51.04 |
-10:02:30.8 |
HIP 59863 |
18.24 |
| 2026-08-06 00:00 |
12:18:09.75 |
-10:04:17.9 |
HIP 59863 |
22.86 |
| 2026-08-06 12:00 |
12:18:28.54 |
-10:06:05.6 |
HIP 59863 |
27.61 |
| 2026-08-07 00:00 |
12:18:47.41 |
-10:07:53.9 |
HIP 59863 |
32.44 |
| 2026-08-07 12:00 |
12:19:06.36 |
-10:09:42.8 |
HIP 59863 |
37.34 |
| 2026-08-08 00:00 |
12:19:25.39 |
-10:11:32.4 |
HIP 60160 |
38.08 |
| 2026-08-08 12:00 |
12:19:44.49 |
-10:13:22.6 |
HIP 60160 |
35.10 |
| 2026-08-09 00:00 |
12:20:03.67 |
-10:15:13.5 |
HIP 60160 |
32.62 |
| 2026-08-09 12:00 |
12:20:22.92 |
-10:17:04.9 |
HIP 60160 |
30.78 |
| 2026-08-10 00:00 |
12:20:42.25 |
-10:18:56.9 |
HIP 60160 |
29.69 |
| 2026-08-10 12:00 |
12:21:01.66 |
-10:20:49.6 |
HIP 60160 |
29.46 |
| 2026-08-11 00:00 |
12:21:21.14 |
-10:22:42.9 |
HIP 60160 |
30.11 |
| 2026-08-11 12:00 |
12:21:40.69 |
-10:24:36.7 |
HIP 60160 |
31.60 |
| 2026-08-12 00:00 |
12:22:00.31 |
-10:26:31.2 |
HIP 60160 |
33.83 |
| 2026-08-12 12:00 |
12:22:20.01 |
-10:28:26.3 |
HIP 60518 |
29.90 |
| 2026-08-13 00:00 |
12:22:39.78 |
-10:30:21.9 |
HIP 60518 |
25.11 |
| 2026-08-13 12:00 |
12:22:59.62 |
-10:32:18.1 |
HIP 60518 |
20.52 |
| 2026-08-14 00:00 |
12:23:19.52 |
-10:34:14.9 |
HIP 60518 |
16.31 |
| 2026-08-14 12:00 |
12:23:39.50 |
-10:36:12.3 |
HIP 60518 |
12.90 |
| 2026-08-15 00:00 |
12:23:59.55 |
-10:38:10.3 |
HIP 60518 |
11.08 |
| 2026-08-15 12:00 |
12:24:19.67 |
-10:40:08.8 |
HIP 60518 |
11.64 |
| 2026-08-16 00:00 |
12:24:39.85 |
-10:42:07.8 |
HIP 60518 |
14.33 |
| 2026-08-16 12:00 |
12:25:00.10 |
-10:44:07.5 |
HIP 60518 |
18.25 |
| 2026-08-17 00:00 |
12:25:20.41 |
-10:46:07.7 |
HIP 60518 |
22.78 |
| 2026-08-17 12:00 |
12:25:40.79 |
-10:48:08.4 |
HIP 60518 |
27.63 |
| 2026-08-18 00:00 |
12:26:01.24 |
-10:50:09.7 |
HIP 60518 |
32.67 |
| 2026-08-18 12:00 |
12:26:21.75 |
-10:52:11.5 |
HIP 60876 |
34.35 |
| 2026-08-19 00:00 |
12:26:42.32 |
-10:54:13.8 |
HIP 60876 |
28.94 |