| 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) |
| 2026-05-12 00:00 |
01:10:56.93 |
-51:12:40.8 |
HIP 5676 |
26.98 |
| 2026-05-12 12:00 |
01:11:17.52 |
-51:14:06.6 |
HIP 5676 |
23.75 |
| 2026-05-13 00:00 |
01:11:37.99 |
-51:15:34.3 |
HIP 5676 |
20.61 |
| 2026-05-13 12:00 |
01:11:58.33 |
-51:17:04.0 |
HIP 5676 |
17.59 |
| 2026-05-14 00:00 |
01:12:18.56 |
-51:18:35.7 |
HIP 5676 |
14.77 |
| 2026-05-14 12:00 |
01:12:38.66 |
-51:20:09.4 |
HIP 5676 |
12.27 |
| 2026-05-15 00:00 |
01:12:58.63 |
-51:21:45.0 |
HIP 5676 |
10.35 |
| 2026-05-15 12:00 |
01:13:18.49 |
-51:23:22.6 |
HIP 5676 |
9.34 |
| 2026-05-16 00:00 |
01:13:38.21 |
-51:25:02.2 |
HIP 5676 |
9.54 |
| 2026-05-16 12:00 |
01:13:57.81 |
-51:26:43.7 |
HIP 5676 |
10.88 |
| 2026-05-17 00:00 |
01:14:17.28 |
-51:28:27.2 |
HIP 5676 |
13.01 |
| 2026-05-17 12:00 |
01:14:36.61 |
-51:30:12.6 |
HIP 5676 |
15.61 |
| 2026-05-18 00:00 |
01:14:55.82 |
-51:32:00.0 |
HIP 5676 |
18.48 |
| 2026-05-18 12:00 |
01:15:14.89 |
-51:33:49.3 |
HIP 5676 |
21.51 |
| 2026-05-19 00:00 |
01:15:33.83 |
-51:35:40.5 |
HIP 6020 |
23.18 |
| 2026-05-19 12:00 |
01:15:52.63 |
-51:37:33.7 |
HIP 6020 |
22.64 |
| 2026-05-20 00:00 |
01:16:11.29 |
-51:39:28.8 |
HIP 6026 |
21.71 |
| 2026-05-20 12:00 |
01:16:29.82 |
-51:41:25.8 |
HIP 6026 |
18.59 |
| 2026-05-21 00:00 |
01:16:48.21 |
-51:43:24.8 |
HIP 6026 |
15.60 |
| 2026-05-21 12:00 |
01:17:06.45 |
-51:45:25.6 |
HIP 6026 |
12.82 |
| 2026-05-22 00:00 |
01:17:24.56 |
-51:47:28.4 |
HIP 6026 |
10.42 |
| 2026-05-22 12:00 |
01:17:42.52 |
-51:49:33.1 |
HIP 6026 |
8.74 |
| 2026-05-23 00:00 |
01:18:00.33 |
-51:51:39.6 |
HIP 6026 |
8.21 |
| 2026-05-23 12:00 |
01:18:18.01 |
-51:53:48.0 |
HIP 6026 |
9.04 |
| 2026-05-24 00:00 |
01:18:35.53 |
-51:55:58.3 |
HIP 6026 |
10.93 |
| 2026-05-24 12:00 |
01:18:52.91 |
-51:58:10.5 |
HIP 6076 |
11.62 |
| 2026-05-25 00:00 |
01:19:10.14 |
-52:00:24.6 |
HIP 6076 |
12.42 |
| 2026-05-25 12:00 |
01:19:27.22 |
-52:02:40.5 |
HIP 6076 |
14.02 |
| 2026-05-26 00:00 |
01:19:44.15 |
-52:04:58.2 |
HIP 6076 |
16.19 |
| 2026-05-26 12:00 |
01:20:00.93 |
-52:07:17.8 |
HIP 6364 |
16.11 |
| 2026-05-27 00:00 |
01:20:17.55 |
-52:09:39.3 |
HIP 6364 |
14.25 |
| 2026-05-27 12:00 |
01:20:34.02 |
-52:12:02.6 |
HIP 6364 |
13.11 |
| 2026-05-28 00:00 |
01:20:50.33 |
-52:14:27.7 |
HIP 6394 |
12.12 |
| 2026-05-28 12:00 |
01:21:06.49 |
-52:16:54.6 |
HIP 6394 |
10.09 |
| 2026-05-29 00:00 |
01:21:22.49 |
-52:19:23.4 |
HIP 6394 |
9.05 |
| 2026-05-29 12:00 |
01:21:38.33 |
-52:21:53.9 |
HIP 6394 |
9.33 |
| 2026-05-30 00:00 |
01:21:54.01 |
-52:24:26.3 |
HIP 6394 |
10.83 |
| 2026-05-30 12:00 |
01:22:09.53 |
-52:27:00.4 |
HIP 6394 |
13.14 |
| 2026-05-31 00:00 |
01:22:24.88 |
-52:29:36.4 |
HIP 6546 |
15.63 |
| 2026-05-31 12:00 |
01:22:40.07 |
-52:32:14.1 |
HIP 6546 |
13.37 |
| 2026-06-01 00:00 |
01:22:55.10 |
-52:34:53.7 |
HIP 6546 |
11.77 |
| 2026-06-01 12:00 |
01:23:09.95 |
-52:37:35.0 |
HIP 6546 |
11.12 |
| 2026-06-02 00:00 |
01:23:24.64 |
-52:40:18.0 |
HIP 6546 |
11.60 |