C/2025 A3 (Tsuchinshan)
| Parameter |
Value |
| Designation |
C/2025 A3 (Tsuchinshan) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2026-03-14T23:03:25.292160Z |
| Orbit solution date (soln_date, UTC) |
2025-04-11T14:45:03Z |
| Obs used |
87 |
| 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) |
2025-02-05.0000000 |
| e |
0.43149135 |
| q (au) |
5.792522 |
| a (au) |
10.188978 |
| i (deg) |
9.977261 |
| Ω (om, deg) |
322.434177 |
| ω (w, deg) |
222.296208 |
| M (ma, deg) |
347.788448 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.217 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.217 |
| n |
2.000 |
| gf |
0.962 |
| gb |
-1.000 |
| k |
1.000 |
| δ90 |
9.993 |
| 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) |
| 2026-02-03 00:00 |
12:21:55.89 |
-09:59:30.4 |
HIP 60420 |
23.83 |
| 2026-02-03 12:00 |
12:21:52.59 |
-10:00:09.3 |
HIP 60420 |
24.87 |
| 2026-02-04 00:00 |
12:21:49.13 |
-10:00:47.2 |
HIP 60420 |
25.93 |
| 2026-02-04 12:00 |
12:21:45.51 |
-10:01:23.9 |
HIP 60420 |
27.01 |
| 2026-02-05 00:00 |
12:21:41.74 |
-10:01:59.6 |
HIP 60420 |
28.11 |
| 2026-02-05 12:00 |
12:21:37.82 |
-10:02:34.2 |
HIP 60420 |
29.23 |
| 2026-02-06 00:00 |
12:21:33.74 |
-10:03:07.7 |
HIP 60420 |
30.38 |
| 2026-02-06 12:00 |
12:21:29.51 |
-10:03:40.1 |
HIP 60248 |
30.97 |
| 2026-02-07 00:00 |
12:21:25.13 |
-10:04:11.4 |
HIP 60248 |
31.37 |
| 2026-02-07 12:00 |
12:21:20.59 |
-10:04:41.7 |
HIP 60248 |
31.79 |
| 2026-02-08 00:00 |
12:21:15.91 |
-10:05:10.8 |
HIP 60248 |
32.23 |
| 2026-02-08 12:00 |
12:21:11.07 |
-10:05:38.9 |
HIP 60248 |
32.70 |
| 2026-02-09 00:00 |
12:21:06.08 |
-10:06:05.8 |
HIP 60248 |
33.19 |
| 2026-02-09 12:00 |
12:21:00.95 |
-10:06:31.7 |
HIP 60248 |
33.71 |
| 2026-02-10 00:00 |
12:20:55.66 |
-10:06:56.4 |
HIP 60248 |
34.26 |
| 2026-02-10 12:00 |
12:20:50.23 |
-10:07:20.1 |
HIP 60248 |
34.85 |
| 2026-02-11 00:00 |
12:20:44.65 |
-10:07:42.7 |
HIP 60248 |
35.47 |
| 2026-02-11 12:00 |
12:20:38.92 |
-10:08:04.2 |
HIP 60248 |
36.13 |
| 2026-02-12 00:00 |
12:20:33.05 |
-10:08:24.5 |
HIP 60248 |
36.82 |
| 2026-02-12 12:00 |
12:20:27.03 |
-10:08:43.8 |
HIP 60248 |
37.55 |
| 2026-02-13 00:00 |
12:20:20.88 |
-10:09:02.0 |
HIP 60248 |
38.33 |
| 2026-02-13 12:00 |
12:20:14.57 |
-10:09:19.1 |
HIP 60160 |
38.45 |
| 2026-02-14 00:00 |
12:20:08.13 |
-10:09:35.1 |
HIP 60160 |
38.20 |
| 2026-02-14 12:00 |
12:20:01.55 |
-10:09:50.0 |
HIP 60160 |
38.04 |
| 2026-02-15 00:00 |
12:19:54.83 |
-10:10:03.8 |
HIP 60160 |
37.97 |
| 2026-02-15 12:00 |
12:19:47.97 |
-10:10:16.5 |
HIP 60160 |
38.00 |
| 2026-02-16 00:00 |
12:19:40.97 |
-10:10:28.1 |
HIP 60160 |
38.12 |
| 2026-02-16 12:00 |
12:19:33.83 |
-10:10:38.6 |
HIP 60160 |
38.36 |
| 2026-02-17 00:00 |
12:19:26.57 |
-10:10:48.1 |
HIP 60160 |
38.70 |
| 2026-02-17 12:00 |
12:19:19.17 |
-10:10:56.4 |
HIP 60160 |
39.14 |
| 2026-02-18 00:00 |
12:19:11.63 |
-10:11:03.7 |
HIP 59863 |
38.86 |
| 2026-02-18 12:00 |
12:19:03.97 |
-10:11:09.9 |
HIP 59863 |
37.04 |
| 2026-02-19 00:00 |
12:18:56.18 |
-10:11:15.1 |
HIP 59863 |
35.19 |
| 2026-02-19 12:00 |
12:18:48.26 |
-10:11:19.1 |
HIP 59863 |
33.31 |
| 2026-02-20 00:00 |
12:18:40.21 |
-10:11:22.1 |
HIP 59863 |
31.41 |
| 2026-02-20 12:00 |
12:18:32.04 |
-10:11:24.1 |
HIP 59863 |
29.48 |
| 2026-02-21 00:00 |
12:18:23.74 |
-10:11:24.9 |
HIP 59863 |
27.53 |
| 2026-02-21 12:00 |
12:18:15.33 |
-10:11:24.8 |
HIP 59863 |
25.56 |
| 2026-02-22 00:00 |
12:18:06.79 |
-10:11:23.5 |
HIP 59863 |
23.57 |
| 2026-02-22 12:00 |
12:17:58.14 |
-10:11:21.3 |
HIP 59863 |
21.58 |
| 2026-02-23 00:00 |
12:17:49.37 |
-10:11:17.9 |
HIP 59863 |
19.57 |
| 2026-02-23 12:00 |
12:17:40.48 |
-10:11:13.6 |
HIP 59863 |
17.57 |
| 2026-02-24 00:00 |
12:17:31.48 |
-10:11:08.2 |
HIP 59863 |
15.59 |