| Parameter |
Value |
| Designation |
C/2025 A3 (Tsuchinshan) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2026-03-15T00:48:41.667840Z |
| Orbit solution date (soln_date, UTC) |
2026-04-27T13:42:21Z |
| Obs used |
101 |
| NEO |
- |
| M1 |
13.500 |
| K1 |
4.500 |
| 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) |
2025-04-12.0000000 |
| e |
0.43162591 |
| q (au) |
5.792455 |
| a (au) |
10.191273 |
| i (deg) |
9.977406 |
| Ω (om, deg) |
322.434258 |
| ω (w, deg) |
222.303442 |
| M (ma, deg) |
349.789784 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.165 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.165 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.518 |
| 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) |
| 2026-05-12 00:00 |
11:52:20.06 |
-08:14:23.9 |
HIP 57806 |
22.69 |
| 2026-05-12 12:00 |
11:52:16.96 |
-08:13:48.6 |
HIP 57806 |
21.72 |
| 2026-05-13 00:00 |
11:52:14.00 |
-08:13:14.1 |
HIP 57806 |
20.80 |
| 2026-05-13 12:00 |
11:52:11.21 |
-08:12:40.3 |
HIP 57806 |
19.90 |
| 2026-05-14 00:00 |
11:52:08.56 |
-08:12:07.2 |
HIP 57806 |
19.05 |
| 2026-05-14 12:00 |
11:52:06.07 |
-08:11:34.9 |
HIP 57806 |
18.23 |
| 2026-05-15 00:00 |
11:52:03.73 |
-08:11:03.3 |
HIP 57806 |
17.45 |
| 2026-05-15 12:00 |
11:52:01.55 |
-08:10:32.5 |
HIP 57806 |
16.70 |
| 2026-05-16 00:00 |
11:51:59.52 |
-08:10:02.5 |
HIP 57806 |
16.00 |
| 2026-05-16 12:00 |
11:51:57.64 |
-08:09:33.2 |
HIP 57806 |
15.33 |
| 2026-05-17 00:00 |
11:51:55.93 |
-08:09:04.8 |
HIP 57806 |
14.69 |
| 2026-05-17 12:00 |
11:51:54.36 |
-08:08:37.1 |
HIP 57806 |
14.10 |
| 2026-05-18 00:00 |
11:51:52.96 |
-08:08:10.2 |
HIP 57806 |
13.55 |
| 2026-05-18 12:00 |
11:51:51.71 |
-08:07:44.1 |
HIP 57806 |
13.03 |
| 2026-05-19 00:00 |
11:51:50.61 |
-08:07:18.9 |
HIP 57806 |
12.56 |
| 2026-05-19 12:00 |
11:51:49.68 |
-08:06:54.4 |
HIP 57806 |
12.12 |
| 2026-05-20 00:00 |
11:51:48.90 |
-08:06:30.8 |
HIP 57806 |
11.73 |
| 2026-05-20 12:00 |
11:51:48.27 |
-08:06:08.0 |
HIP 57806 |
11.38 |
| 2026-05-21 00:00 |
11:51:47.81 |
-08:05:46.1 |
HIP 57806 |
11.08 |
| 2026-05-21 12:00 |
11:51:47.50 |
-08:05:25.0 |
HIP 57806 |
10.82 |
| 2026-05-22 00:00 |
11:51:47.34 |
-08:05:04.7 |
HIP 57806 |
10.60 |
| 2026-05-22 12:00 |
11:51:47.35 |
-08:04:45.3 |
HIP 57806 |
10.44 |
| 2026-05-23 00:00 |
11:51:47.51 |
-08:04:26.7 |
HIP 57806 |
10.32 |
| 2026-05-23 12:00 |
11:51:47.83 |
-08:04:09.0 |
HIP 57806 |
10.25 |
| 2026-05-24 00:00 |
11:51:48.30 |
-08:03:52.1 |
HIP 57806 |
10.23 |
| 2026-05-24 12:00 |
11:51:48.93 |
-08:03:36.1 |
HIP 57806 |
10.27 |
| 2026-05-25 00:00 |
11:51:49.72 |
-08:03:21.0 |
HIP 57806 |
10.35 |
| 2026-05-25 12:00 |
11:51:50.66 |
-08:03:06.7 |
HIP 57806 |
10.48 |
| 2026-05-26 00:00 |
11:51:51.76 |
-08:02:53.3 |
HIP 57806 |
10.66 |
| 2026-05-26 12:00 |
11:51:53.02 |
-08:02:40.8 |
HIP 57806 |
10.90 |
| 2026-05-27 00:00 |
11:51:54.43 |
-08:02:29.1 |
HIP 57806 |
11.18 |
| 2026-05-27 12:00 |
11:51:56.00 |
-08:02:18.4 |
HIP 57806 |
11.51 |
| 2026-05-28 00:00 |
11:51:57.72 |
-08:02:08.5 |
HIP 57806 |
11.88 |
| 2026-05-28 12:00 |
11:51:59.59 |
-08:01:59.5 |
HIP 57806 |
12.30 |
| 2026-05-29 00:00 |
11:52:01.62 |
-08:01:51.3 |
HIP 57806 |
12.77 |
| 2026-05-29 12:00 |
11:52:03.81 |
-08:01:44.1 |
HIP 57806 |
13.28 |
| 2026-05-30 00:00 |
11:52:06.15 |
-08:01:37.7 |
HIP 57806 |
13.84 |
| 2026-05-30 12:00 |
11:52:08.64 |
-08:01:32.3 |
HIP 57806 |
14.43 |
| 2026-05-31 00:00 |
11:52:11.29 |
-08:01:27.7 |
HIP 57806 |
15.07 |
| 2026-05-31 12:00 |
11:52:14.09 |
-08:01:24.1 |
HIP 57806 |
15.75 |
| 2026-06-01 00:00 |
11:52:17.05 |
-08:01:21.3 |
HIP 57806 |
16.47 |
| 2026-06-01 12:00 |
11:52:20.16 |
-08:01:19.4 |
HIP 57806 |
17.23 |
| 2026-06-02 00:00 |
11:52:23.42 |
-08:01:18.5 |
HIP 57806 |
18.04 |