12P/Pons-Brooks
| 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
$$
M_a = (6.964 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
6.964 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.868 |
| k |
0.930 |
| 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 |
+7.5143 |
-5.357 |
| 2023-07-20 |
2023-08-30 |
-28.1370 |
+14.641 |
| 2023-08-30 |
2024-04-20 |
+0.2590 |
-0.832 |
| 2024-04-21 |
2024-10-11 |
-2.5860 |
-1.437 |
| 2024-10-11 |
2025-06-07 |
+15.0161 |
-9.067 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
17:02:59.76 |
-36:46:48.3 |
HIP 83527 |
16.96 |
| 2026-02-03 12:00 |
17:03:10.66 |
-36:47:11.3 |
HIP 83527 |
15.31 |
| 2026-02-04 00:00 |
17:03:21.42 |
-36:47:34.4 |
HIP 83527 |
13.83 |
| 2026-02-04 12:00 |
17:03:32.05 |
-36:47:57.5 |
HIP 83527 |
12.58 |
| 2026-02-05 00:00 |
17:03:42.55 |
-36:48:20.7 |
HIP 83527 |
11.61 |
| 2026-02-05 12:00 |
17:03:52.91 |
-36:48:43.9 |
HIP 83527 |
11.00 |
| 2026-02-06 00:00 |
17:04:03.14 |
-36:49:07.2 |
HIP 83527 |
10.77 |
| 2026-02-06 12:00 |
17:04:13.23 |
-36:49:30.5 |
HIP 83527 |
10.95 |
| 2026-02-07 00:00 |
17:04:23.19 |
-36:49:53.9 |
HIP 83527 |
11.50 |
| 2026-02-07 12:00 |
17:04:33.01 |
-36:50:17.3 |
HIP 83527 |
12.35 |
| 2026-02-08 00:00 |
17:04:42.69 |
-36:50:40.8 |
HIP 83527 |
13.44 |
| 2026-02-08 12:00 |
17:04:52.24 |
-36:51:04.3 |
HIP 83527 |
14.70 |
| 2026-02-09 00:00 |
17:05:01.64 |
-36:51:27.9 |
HIP 83527 |
16.09 |
| 2026-02-09 12:00 |
17:05:10.91 |
-36:51:51.5 |
HIP 83527 |
17.55 |
| 2026-02-10 00:00 |
17:05:20.03 |
-36:52:15.2 |
HIP 83701 |
18.73 |
| 2026-02-10 12:00 |
17:05:29.01 |
-36:52:38.9 |
HIP 83701 |
17.26 |
| 2026-02-11 00:00 |
17:05:37.85 |
-36:53:02.6 |
HIP 83701 |
15.88 |
| 2026-02-11 12:00 |
17:05:46.54 |
-36:53:26.3 |
HIP 83701 |
14.61 |
| 2026-02-12 00:00 |
17:05:55.09 |
-36:53:50.1 |
HIP 83701 |
13.48 |
| 2026-02-12 12:00 |
17:06:03.50 |
-36:54:13.9 |
HIP 83701 |
12.49 |
| 2026-02-13 00:00 |
17:06:11.76 |
-36:54:37.8 |
HIP 83701 |
11.68 |
| 2026-02-13 12:00 |
17:06:19.87 |
-36:55:01.6 |
HIP 83701 |
11.08 |
| 2026-02-14 00:00 |
17:06:27.83 |
-36:55:25.5 |
HIP 83701 |
10.70 |
| 2026-02-14 12:00 |
17:06:35.65 |
-36:55:49.4 |
HIP 83701 |
10.55 |
| 2026-02-15 00:00 |
17:06:43.31 |
-36:56:13.3 |
HIP 83701 |
10.64 |
| 2026-02-15 12:00 |
17:06:50.83 |
-36:56:37.2 |
HIP 83701 |
10.95 |
| 2026-02-16 00:00 |
17:06:58.19 |
-36:57:01.1 |
HIP 83701 |
11.44 |
| 2026-02-16 12:00 |
17:07:05.41 |
-36:57:25.1 |
HIP 83701 |
12.08 |
| 2026-02-17 00:00 |
17:07:12.47 |
-36:57:49.0 |
HIP 83701 |
12.84 |
| 2026-02-17 12:00 |
17:07:19.37 |
-36:58:12.9 |
HIP 83701 |
13.69 |
| 2026-02-18 00:00 |
17:07:26.12 |
-36:58:36.9 |
HIP 83701 |
14.60 |
| 2026-02-18 12:00 |
17:07:32.72 |
-36:59:00.8 |
HIP 83701 |
15.56 |
| 2026-02-19 00:00 |
17:07:39.16 |
-36:59:24.7 |
HIP 83701 |
16.55 |
| 2026-02-19 12:00 |
17:07:45.45 |
-36:59:48.6 |
HIP 83701 |
17.56 |
| 2026-02-20 00:00 |
17:07:51.58 |
-37:00:12.5 |
HIP 83701 |
18.58 |
| 2026-02-20 12:00 |
17:07:57.55 |
-37:00:36.4 |
HIP 83789 |
18.74 |
| 2026-02-21 00:00 |
17:08:03.36 |
-37:01:00.2 |
HIP 83789 |
18.76 |
| 2026-02-21 12:00 |
17:08:09.02 |
-37:01:24.1 |
HIP 83789 |
18.84 |
| 2026-02-22 00:00 |
17:08:14.51 |
-37:01:47.9 |
HIP 83789 |
18.98 |
| 2026-02-22 12:00 |
17:08:19.84 |
-37:02:11.6 |
HIP 83937 |
18.75 |
| 2026-02-23 00:00 |
17:08:25.02 |
-37:02:35.4 |
HIP 83937 |
17.76 |
| 2026-02-23 12:00 |
17:08:30.03 |
-37:02:59.1 |
HIP 83937 |
16.80 |
| 2026-02-24 00:00 |
17:08:34.88 |
-37:03:22.7 |
HIP 83937 |
15.88 |