| Parameter |
Value |
| Designation |
C/2025 F2 (SWAN) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2025-05-01T03:51:29.594880Z |
| Orbit solution date (soln_date, UTC) |
2025-09-30T14:13:43Z |
| Obs used |
375 |
| NEO |
- |
| M1 |
12.300 |
| K1 |
13.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2025-03-22T12:00:00Z |
| Discovery magnitude (MPC) |
- |
| Discovery observatory (MPC) |
249 · SOHO |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2025-03-31.0000000 |
| e |
1.00013474 |
| q (au) |
0.333496 |
| a (au) |
-2475.174637 |
| i (deg) |
90.364801 |
| Ω (om, deg) |
329.839874 |
| ω (w, deg) |
153.835634 |
| M (ma, deg) |
-0.000249 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.159 + 3.735\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.159 |
| n |
3.735 |
| gf |
0.800 |
| gb |
-0.536 |
| k |
0.800 |
| δ90 |
9.999 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2024-09-03 |
2025-04-05 |
+5.8025 |
+0.079 |
| 2025-04-05 |
2025-04-21 |
-13.4640 |
-2.999 |
| 2025-04-21 |
2025-04-29 |
-20.8594 |
-6.023 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
01:25:33.26 |
-60:07:45.9 |
HIP 6531 |
32.26 |
| 2026-07-29 12:00 |
01:25:16.65 |
-60:12:09.1 |
HIP 6531 |
27.42 |
| 2026-07-30 00:00 |
01:24:59.67 |
-60:16:31.7 |
HIP 6531 |
22.58 |
| 2026-07-30 12:00 |
01:24:42.32 |
-60:20:53.8 |
HIP 6531 |
17.75 |
| 2026-07-31 00:00 |
01:24:24.59 |
-60:25:15.2 |
HIP 6531 |
12.94 |
| 2026-07-31 12:00 |
01:24:06.48 |
-60:29:36.0 |
HIP 6531 |
8.22 |
| 2026-08-01 00:00 |
01:23:47.99 |
-60:33:56.1 |
HIP 6531 |
3.95 |
| 2026-08-01 12:00 |
01:23:29.13 |
-60:38:15.5 |
HIP 6531 |
3.43 |
| 2026-08-02 00:00 |
01:23:09.88 |
-60:42:34.2 |
HIP 6531 |
7.51 |
| 2026-08-02 12:00 |
01:22:50.26 |
-60:46:52.0 |
HIP 6449 |
5.57 |
| 2026-08-03 00:00 |
01:22:30.25 |
-60:51:09.1 |
HIP 6449 |
2.86 |
| 2026-08-03 12:00 |
01:22:09.86 |
-60:55:25.3 |
HIP 6424 |
5.23 |
| 2026-08-04 00:00 |
01:21:49.09 |
-60:59:40.6 |
HIP 6424 |
4.70 |
| 2026-08-04 12:00 |
01:21:27.93 |
-61:03:55.1 |
HIP 6424 |
8.13 |
| 2026-08-05 00:00 |
01:21:06.39 |
-61:08:08.5 |
HIP 6274 |
11.67 |
| 2026-08-05 12:00 |
01:20:44.47 |
-61:12:21.0 |
HIP 6274 |
6.87 |
| 2026-08-06 00:00 |
01:20:22.16 |
-61:16:32.5 |
HIP 6274 |
2.76 |
| 2026-08-06 12:00 |
01:19:59.46 |
-61:20:43.0 |
HIP 6274 |
4.22 |
| 2026-08-07 00:00 |
01:19:36.37 |
-61:24:52.3 |
HIP 6274 |
8.83 |
| 2026-08-07 12:00 |
01:19:12.90 |
-61:29:00.5 |
HIP 6274 |
13.72 |
| 2026-08-08 00:00 |
01:18:49.05 |
-61:33:07.6 |
HIP 6024 |
10.30 |
| 2026-08-08 12:00 |
01:18:24.80 |
-61:37:13.5 |
HIP 6024 |
7.69 |
| 2026-08-09 00:00 |
01:18:00.17 |
-61:41:18.2 |
HIP 6024 |
7.87 |
| 2026-08-09 12:00 |
01:17:35.15 |
-61:45:21.6 |
HIP 6024 |
10.71 |
| 2026-08-10 00:00 |
01:17:09.74 |
-61:49:23.7 |
HIP 6024 |
14.75 |
| 2026-08-10 12:00 |
01:16:43.95 |
-61:53:24.5 |
HIP 5872 |
16.24 |
| 2026-08-11 00:00 |
01:16:17.77 |
-61:57:23.9 |
HIP 5872 |
11.21 |
| 2026-08-11 12:00 |
01:15:51.21 |
-62:01:21.9 |
HIP 5872 |
6.17 |
| 2026-08-12 00:00 |
01:15:24.26 |
-62:05:18.5 |
HIP 5872 |
1.25 |
| 2026-08-12 12:00 |
01:14:56.93 |
-62:09:13.5 |
HIP 5872 |
4.01 |
| 2026-08-13 00:00 |
01:14:29.21 |
-62:13:07.1 |
HIP 5872 |
9.05 |
| 2026-08-13 12:00 |
01:14:01.12 |
-62:16:59.1 |
HIP 5736 |
9.13 |
| 2026-08-14 00:00 |
01:13:32.64 |
-62:20:49.5 |
HIP 5736 |
5.21 |
| 2026-08-14 12:00 |
01:13:03.78 |
-62:24:38.3 |
HIP 5736 |
4.77 |
| 2026-08-15 00:00 |
01:12:34.55 |
-62:28:25.5 |
HIP 5736 |
8.37 |
| 2026-08-15 12:00 |
01:12:04.94 |
-62:32:10.9 |
HIP 5736 |
13.02 |
| 2026-08-16 00:00 |
01:11:34.95 |
-62:35:54.7 |
HIP 5736 |
17.91 |
| 2026-08-16 12:00 |
01:11:04.59 |
-62:39:36.6 |
HIP 5736 |
22.89 |
| 2026-08-17 00:00 |
01:10:33.87 |
-62:43:16.8 |
HIP 5736 |
27.92 |
| 2026-08-17 12:00 |
01:10:02.77 |
-62:46:55.1 |
HIP 5736 |
32.98 |
| 2026-08-18 00:00 |
01:09:31.31 |
-62:50:31.6 |
HIP 5238 |
35.26 |
| 2026-08-18 12:00 |
01:08:59.48 |
-62:54:06.2 |
HIP 5238 |
30.41 |
| 2026-08-19 00:00 |
01:08:27.29 |
-62:57:38.8 |
HIP 5238 |
25.66 |