C/2025 A4 (PANSTARRS)
| Parameter |
Value |
| Designation |
C/2025 A4 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2025-01-13T02:45:57.608640Z |
| Orbit solution date (soln_date, UTC) |
2025-06-26T10:13:11Z |
| Obs used |
100 |
| NEO |
- |
| M1 |
15.400 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2025-01-03T15:06:00.892800Z |
| Discovery magnitude (MPC) |
21.05 w |
| Discovery observatory (MPC) |
F52 · Pan-STARRS 2, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2025-03-05.0000000 |
| e |
0.65381554 |
| q (au) |
3.824179 |
| a (au) |
11.046652 |
| i (deg) |
32.025692 |
| Ω (om, deg) |
69.912504 |
| ω (w, deg) |
102.791064 |
| M (ma, deg) |
1.365984 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.631 + 3.439\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.631 |
| n |
3.439 |
| gf |
1.000 |
| gb |
-0.628 |
| k |
0.800 |
| 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) |
| 2026-02-03 00:00 |
16:16:17.04 |
-11:05:40.9 |
HIP 79663 |
13.10 |
| 2026-02-03 12:00 |
16:16:34.90 |
-11:07:12.5 |
HIP 79663 |
17.71 |
| 2026-02-04 00:00 |
16:16:52.60 |
-11:08:43.5 |
HIP 79663 |
22.30 |
| 2026-02-04 12:00 |
16:17:10.15 |
-11:10:13.9 |
HIP 79915 |
23.97 |
| 2026-02-05 00:00 |
16:17:27.54 |
-11:11:43.8 |
HIP 79915 |
19.45 |
| 2026-02-05 12:00 |
16:17:44.78 |
-11:13:13.2 |
HIP 79915 |
14.98 |
| 2026-02-06 00:00 |
16:18:01.86 |
-11:14:41.9 |
HIP 79915 |
10.55 |
| 2026-02-06 12:00 |
16:18:18.78 |
-11:16:10.1 |
HIP 79915 |
6.17 |
| 2026-02-07 00:00 |
16:18:35.54 |
-11:17:37.8 |
HIP 79915 |
1.96 |
| 2026-02-07 12:00 |
16:18:52.14 |
-11:19:04.9 |
HIP 79915 |
2.73 |
| 2026-02-08 00:00 |
16:19:08.57 |
-11:20:31.5 |
HIP 79915 |
6.91 |
| 2026-02-08 12:00 |
16:19:24.85 |
-11:21:57.5 |
HIP 79915 |
11.13 |
| 2026-02-09 00:00 |
16:19:40.95 |
-11:23:23.0 |
HIP 80058 |
14.26 |
| 2026-02-09 12:00 |
16:19:56.90 |
-11:24:48.0 |
HIP 80058 |
10.35 |
| 2026-02-10 00:00 |
16:20:12.67 |
-11:26:12.4 |
HIP 80058 |
6.77 |
| 2026-02-10 12:00 |
16:20:28.28 |
-11:27:36.3 |
HIP 80058 |
4.31 |
| 2026-02-11 00:00 |
16:20:43.72 |
-11:28:59.7 |
HIP 80058 |
4.91 |
| 2026-02-11 12:00 |
16:20:58.99 |
-11:30:22.6 |
HIP 80058 |
7.84 |
| 2026-02-12 00:00 |
16:21:14.09 |
-11:31:45.0 |
HIP 80058 |
11.39 |
| 2026-02-12 12:00 |
16:21:29.01 |
-11:33:06.8 |
HIP 80058 |
15.09 |
| 2026-02-13 00:00 |
16:21:43.77 |
-11:34:28.2 |
HIP 80058 |
18.83 |
| 2026-02-13 12:00 |
16:21:58.34 |
-11:35:49.0 |
HIP 80295 |
21.71 |
| 2026-02-14 00:00 |
16:22:12.75 |
-11:37:09.4 |
HIP 80295 |
18.25 |
| 2026-02-14 12:00 |
16:22:26.97 |
-11:38:29.3 |
HIP 80295 |
14.97 |
| 2026-02-15 00:00 |
16:22:41.02 |
-11:39:48.7 |
HIP 80295 |
12.00 |
| 2026-02-15 12:00 |
16:22:54.89 |
-11:41:07.6 |
HIP 80295 |
9.58 |
| 2026-02-16 00:00 |
16:23:08.58 |
-11:42:26.0 |
HIP 80295 |
8.14 |
| 2026-02-16 12:00 |
16:23:22.10 |
-11:43:43.9 |
HIP 80295 |
8.16 |
| 2026-02-17 00:00 |
16:23:35.42 |
-11:45:01.4 |
HIP 80295 |
9.59 |
| 2026-02-17 12:00 |
16:23:48.57 |
-11:46:18.5 |
HIP 80354 |
9.48 |
| 2026-02-18 00:00 |
16:24:01.53 |
-11:47:35.0 |
HIP 80354 |
6.78 |
| 2026-02-18 12:00 |
16:24:14.31 |
-11:48:51.2 |
HIP 80354 |
5.04 |
| 2026-02-19 00:00 |
16:24:26.90 |
-11:50:06.8 |
HIP 80354 |
5.23 |
| 2026-02-19 12:00 |
16:24:39.31 |
-11:51:22.1 |
HIP 80354 |
7.14 |
| 2026-02-20 00:00 |
16:24:51.53 |
-11:52:36.9 |
HIP 80354 |
9.76 |
| 2026-02-20 12:00 |
16:25:03.56 |
-11:53:51.2 |
HIP 80354 |
12.62 |
| 2026-02-21 00:00 |
16:25:15.40 |
-11:55:05.2 |
HIP 80354 |
15.56 |
| 2026-02-21 12:00 |
16:25:27.05 |
-11:56:18.7 |
HIP 80354 |
18.53 |
| 2026-02-22 00:00 |
16:25:38.51 |
-11:57:31.8 |
HIP 80354 |
21.48 |
| 2026-02-22 12:00 |
16:25:49.78 |
-11:58:44.5 |
HIP 80576 |
19.92 |
| 2026-02-23 00:00 |
16:26:00.86 |
-11:59:56.8 |
HIP 80576 |
16.96 |
| 2026-02-23 12:00 |
16:26:11.74 |
-12:01:08.7 |
HIP 80576 |
14.06 |
| 2026-02-24 00:00 |
16:26:22.44 |
-12:02:20.2 |
HIP 80576 |
11.21 |