| 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) |
| 2026-06-01 00:00 |
16:35:22.37 |
-36:27:19.6 |
HIP 81197 |
23.88 |
| 2026-06-01 12:00 |
16:35:03.33 |
-36:26:07.0 |
HIP 81197 |
22.47 |
| 2026-06-02 00:00 |
16:34:44.31 |
-36:24:53.7 |
HIP 81197 |
21.72 |
| 2026-06-02 12:00 |
16:34:25.32 |
-36:23:39.8 |
HIP 81197 |
21.69 |
| 2026-06-03 00:00 |
16:34:06.37 |
-36:22:25.3 |
HIP 81197 |
22.38 |
| 2026-06-03 12:00 |
16:33:47.44 |
-36:21:10.1 |
HIP 81197 |
23.73 |
| 2026-06-04 00:00 |
16:33:28.56 |
-36:19:54.3 |
HIP 81197 |
25.63 |
| 2026-06-04 12:00 |
16:33:09.71 |
-36:18:37.9 |
HIP 80938 |
22.31 |
| 2026-06-05 00:00 |
16:32:50.90 |
-36:17:20.9 |
HIP 80938 |
18.48 |
| 2026-06-05 12:00 |
16:32:32.13 |
-36:16:03.3 |
HIP 80938 |
14.73 |
| 2026-06-06 00:00 |
16:32:13.40 |
-36:14:45.1 |
HIP 80938 |
11.17 |
| 2026-06-06 12:00 |
16:31:54.72 |
-36:13:26.3 |
HIP 80938 |
8.01 |
| 2026-06-07 00:00 |
16:31:36.09 |
-36:12:06.9 |
HIP 80938 |
5.95 |
| 2026-06-07 12:00 |
16:31:17.51 |
-36:10:47.0 |
HIP 80938 |
6.18 |
| 2026-06-08 00:00 |
16:30:58.98 |
-36:09:26.5 |
HIP 80938 |
8.52 |
| 2026-06-08 12:00 |
16:30:40.50 |
-36:08:05.4 |
HIP 80938 |
11.76 |
| 2026-06-09 00:00 |
16:30:22.08 |
-36:06:43.8 |
HIP 80938 |
15.33 |
| 2026-06-09 12:00 |
16:30:03.72 |
-36:05:21.6 |
HIP 80938 |
19.05 |
| 2026-06-10 00:00 |
16:29:45.41 |
-36:03:58.9 |
HIP 80938 |
22.84 |
| 2026-06-10 12:00 |
16:29:27.17 |
-36:02:35.7 |
HIP 80714 |
22.76 |
| 2026-06-11 00:00 |
16:29:08.99 |
-36:01:12.0 |
HIP 80714 |
20.33 |
| 2026-06-11 12:00 |
16:28:50.87 |
-35:59:47.8 |
HIP 80636 |
17.44 |
| 2026-06-12 00:00 |
16:28:32.82 |
-35:58:23.0 |
HIP 80636 |
14.03 |
| 2026-06-12 12:00 |
16:28:14.84 |
-35:56:57.8 |
HIP 80636 |
10.95 |
| 2026-06-13 00:00 |
16:27:56.93 |
-35:55:32.1 |
HIP 80636 |
8.58 |
| 2026-06-13 12:00 |
16:27:39.10 |
-35:54:05.9 |
HIP 80636 |
7.59 |
| 2026-06-14 00:00 |
16:27:21.34 |
-35:52:39.3 |
HIP 80636 |
8.45 |
| 2026-06-14 12:00 |
16:27:03.65 |
-35:51:12.2 |
HIP 80636 |
10.73 |
| 2026-06-15 00:00 |
16:26:46.05 |
-35:49:44.6 |
HIP 80636 |
13.72 |
| 2026-06-15 12:00 |
16:26:28.52 |
-35:48:16.6 |
HIP 80636 |
17.04 |
| 2026-06-16 00:00 |
16:26:11.08 |
-35:46:48.2 |
HIP 80636 |
20.54 |
| 2026-06-16 12:00 |
16:25:53.72 |
-35:45:19.4 |
HIP 80359 |
20.48 |
| 2026-06-17 00:00 |
16:25:36.45 |
-35:43:50.1 |
HIP 80359 |
16.76 |
| 2026-06-17 12:00 |
16:25:19.27 |
-35:42:20.5 |
HIP 80359 |
13.10 |
| 2026-06-18 00:00 |
16:25:02.17 |
-35:40:50.5 |
HIP 80359 |
9.57 |
| 2026-06-18 12:00 |
16:24:45.17 |
-35:39:20.0 |
HIP 80359 |
6.36 |
| 2026-06-19 00:00 |
16:24:28.26 |
-35:37:49.3 |
HIP 80359 |
4.20 |
| 2026-06-19 12:00 |
16:24:11.44 |
-35:36:18.1 |
HIP 80359 |
4.81 |
| 2026-06-20 00:00 |
16:23:54.72 |
-35:34:46.7 |
HIP 80359 |
7.51 |
| 2026-06-20 12:00 |
16:23:38.10 |
-35:33:14.8 |
HIP 80359 |
10.83 |
| 2026-06-21 00:00 |
16:23:21.58 |
-35:31:42.7 |
HIP 80359 |
14.33 |
| 2026-06-21 12:00 |
16:23:05.15 |
-35:30:10.2 |
HIP 80359 |
17.90 |
| 2026-06-22 00:00 |
16:22:48.83 |
-35:28:37.4 |
HIP 80359 |
21.49 |