| Parameter |
Value |
| Designation |
12P/Pons-Brooks |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2024-04-21T03:08:52.180800Z |
| Orbit solution date (soln_date, UTC) |
2026-01-08T08:25:35Z |
| Obs used |
8059 |
| NEO |
Yes |
| M1 |
5.000 |
| K1 |
15.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2023-09-24.0000000 |
| e |
0.95456124 |
| q (au) |
0.780861 |
| a (au) |
17.184915 |
| i (deg) |
74.190910 |
| Ω (om, deg) |
255.855351 |
| ω (w, deg) |
198.987999 |
| M (ma, deg) |
357.092810 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.193 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.193 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.880 |
| k |
0.991 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2020-06-10 |
2023-07-20 |
+7.5133 |
-5.467 |
| 2023-07-20 |
2023-08-30 |
-32.4269 |
+17.092 |
| 2023-08-30 |
2023-12-18 |
+0.8594 |
-0.954 |
| 2023-12-18 |
2024-04-20 |
-0.0616 |
+0.065 |
| 2024-04-21 |
2024-06-16 |
+0.4640 |
-0.450 |
| 2024-06-16 |
2024-10-11 |
-8.2592 |
+0.843 |
| 2024-10-11 |
2025-06-07 |
+15.5927 |
-9.537 |
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 |
16:08:34.29 |
-33:30:53.7 |
HIP 79189 |
14.27 |
| 2026-07-29 12:00 |
16:08:28.11 |
-33:29:23.8 |
HIP 79189 |
15.48 |
| 2026-07-30 00:00 |
16:08:22.09 |
-33:27:54.2 |
HIP 79189 |
16.80 |
| 2026-07-30 12:00 |
16:08:16.22 |
-33:26:24.9 |
HIP 79189 |
18.20 |
| 2026-07-31 00:00 |
16:08:10.49 |
-33:24:56.0 |
HIP 79189 |
19.66 |
| 2026-07-31 12:00 |
16:08:04.92 |
-33:23:27.4 |
HIP 79189 |
21.16 |
| 2026-08-01 00:00 |
16:07:59.49 |
-33:21:59.1 |
HIP 78973 |
22.35 |
| 2026-08-01 12:00 |
16:07:54.21 |
-33:20:31.2 |
HIP 78973 |
23.32 |
| 2026-08-02 00:00 |
16:07:49.08 |
-33:19:03.7 |
HIP 78973 |
24.39 |
| 2026-08-02 12:00 |
16:07:44.10 |
-33:17:36.6 |
HIP 78973 |
25.54 |
| 2026-08-03 00:00 |
16:07:39.27 |
-33:16:09.8 |
HIP 78973 |
26.76 |
| 2026-08-03 12:00 |
16:07:34.58 |
-33:14:43.4 |
HIP 78973 |
28.04 |
| 2026-08-04 00:00 |
16:07:30.04 |
-33:13:17.3 |
HIP 78973 |
29.36 |
| 2026-08-04 12:00 |
16:07:25.65 |
-33:11:51.7 |
HIP 78842 |
30.03 |
| 2026-08-05 00:00 |
16:07:21.41 |
-33:10:26.4 |
HIP 78842 |
28.42 |
| 2026-08-05 12:00 |
16:07:17.32 |
-33:09:01.5 |
HIP 78842 |
26.85 |
| 2026-08-06 00:00 |
16:07:13.37 |
-33:07:37.0 |
HIP 78842 |
25.32 |
| 2026-08-06 12:00 |
16:07:09.57 |
-33:06:13.0 |
HIP 78842 |
23.83 |
| 2026-08-07 00:00 |
16:07:05.92 |
-33:04:49.3 |
HIP 78842 |
22.38 |
| 2026-08-07 12:00 |
16:07:02.41 |
-33:03:26.0 |
HIP 78842 |
20.99 |
| 2026-08-08 00:00 |
16:06:59.05 |
-33:02:03.2 |
HIP 78842 |
19.65 |
| 2026-08-08 12:00 |
16:06:55.84 |
-33:00:40.7 |
HIP 78842 |
18.37 |
| 2026-08-09 00:00 |
16:06:52.77 |
-32:59:18.7 |
HIP 78842 |
17.17 |
| 2026-08-09 12:00 |
16:06:49.85 |
-32:57:57.1 |
HIP 78842 |
16.05 |
| 2026-08-10 00:00 |
16:06:47.07 |
-32:56:36.0 |
HIP 78842 |
15.02 |
| 2026-08-10 12:00 |
16:06:44.44 |
-32:55:15.2 |
HIP 78842 |
14.10 |
| 2026-08-11 00:00 |
16:06:41.96 |
-32:53:54.9 |
HIP 78842 |
13.31 |
| 2026-08-11 12:00 |
16:06:39.62 |
-32:52:35.1 |
HIP 78842 |
12.67 |
| 2026-08-12 00:00 |
16:06:37.43 |
-32:51:15.7 |
HIP 78842 |
12.19 |
| 2026-08-12 12:00 |
16:06:35.38 |
-32:49:56.7 |
HIP 78842 |
11.89 |
| 2026-08-13 00:00 |
16:06:33.48 |
-32:48:38.2 |
HIP 78842 |
11.76 |
| 2026-08-13 12:00 |
16:06:31.71 |
-32:47:20.2 |
HIP 78842 |
11.82 |
| 2026-08-14 00:00 |
16:06:30.10 |
-32:46:02.6 |
HIP 78842 |
12.06 |
| 2026-08-14 12:00 |
16:06:28.62 |
-32:44:45.4 |
HIP 78842 |
12.46 |
| 2026-08-15 00:00 |
16:06:27.29 |
-32:43:28.7 |
HIP 78842 |
13.00 |
| 2026-08-15 12:00 |
16:06:26.10 |
-32:42:12.5 |
HIP 78842 |
13.66 |
| 2026-08-16 00:00 |
16:06:25.05 |
-32:40:56.8 |
HIP 78842 |
14.42 |
| 2026-08-16 12:00 |
16:06:24.15 |
-32:39:41.5 |
HIP 78842 |
15.26 |
| 2026-08-17 00:00 |
16:06:23.38 |
-32:38:26.7 |
HIP 78842 |
16.17 |
| 2026-08-17 12:00 |
16:06:22.76 |
-32:37:12.4 |
HIP 78842 |
17.13 |
| 2026-08-18 00:00 |
16:06:22.27 |
-32:35:58.5 |
HIP 78842 |
18.13 |
| 2026-08-18 12:00 |
16:06:21.93 |
-32:34:45.1 |
HIP 78842 |
19.17 |
| 2026-08-19 00:00 |
16:06:21.72 |
-32:33:32.2 |
HIP 78842 |
20.23 |