| Parameter |
Value |
| Designation |
C/2012 S4 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2013-06-28T00:33:42.019200Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:22Z |
| Obs used |
924 |
| NEO |
- |
| M1 |
9.400 |
| K1 |
8.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2013-04-24.0000000 |
| e |
0.99998199 |
| q (au) |
4.348728 |
| a (au) |
241497.706412 |
| i (deg) |
126.541334 |
| Ω (om, deg) |
173.103524 |
| ω (w, deg) |
163.615485 |
| M (ma, deg) |
359.999999 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.720 + 4.989\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.720 |
| n |
4.989 |
| gf |
0.997 |
| gb |
-0.512 |
| k |
0.800 |
| δ90 |
9.110 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
13:10:12.90 |
-60:02:57.6 |
HIP 64314 |
5.15 |
| 2026-03-26 12:00 |
13:10:04.41 |
-60:02:49.1 |
HIP 64314 |
6.21 |
| 2026-03-27 00:00 |
13:09:55.89 |
-60:02:40.0 |
HIP 64314 |
7.28 |
| 2026-03-27 12:00 |
13:09:47.37 |
-60:02:30.5 |
HIP 64314 |
8.35 |
| 2026-03-28 00:00 |
13:09:38.82 |
-60:02:20.4 |
HIP 64314 |
9.43 |
| 2026-03-28 12:00 |
13:09:30.27 |
-60:02:09.8 |
HIP 64314 |
10.51 |
| 2026-03-29 00:00 |
13:09:21.70 |
-60:01:58.8 |
HIP 64314 |
11.59 |
| 2026-03-29 12:00 |
13:09:13.12 |
-60:01:47.2 |
HIP 64314 |
12.67 |
| 2026-03-30 00:00 |
13:09:04.52 |
-60:01:35.0 |
HIP 64314 |
13.76 |
| 2026-03-30 12:00 |
13:08:55.92 |
-60:01:22.4 |
HIP 64314 |
14.85 |
| 2026-03-31 00:00 |
13:08:47.31 |
-60:01:09.3 |
HIP 64033 |
14.10 |
| 2026-03-31 12:00 |
13:08:38.68 |
-60:00:55.7 |
HIP 64033 |
13.16 |
| 2026-04-01 00:00 |
13:08:30.05 |
-60:00:41.5 |
HIP 64033 |
12.24 |
| 2026-04-01 12:00 |
13:08:21.41 |
-60:00:26.9 |
HIP 64033 |
11.35 |
| 2026-04-02 00:00 |
13:08:12.76 |
-60:00:11.7 |
HIP 64033 |
10.50 |
| 2026-04-02 12:00 |
13:08:04.10 |
-59:59:56.0 |
HIP 64033 |
9.69 |
| 2026-04-03 00:00 |
13:07:55.44 |
-59:59:39.9 |
HIP 64033 |
8.93 |
| 2026-04-03 12:00 |
13:07:46.78 |
-59:59:23.2 |
HIP 64033 |
8.25 |
| 2026-04-04 00:00 |
13:07:38.11 |
-59:59:06.0 |
HIP 64033 |
7.67 |
| 2026-04-04 12:00 |
13:07:29.43 |
-59:58:48.3 |
HIP 64033 |
7.20 |
| 2026-04-05 00:00 |
13:07:20.76 |
-59:58:30.1 |
HIP 64033 |
6.89 |
| 2026-04-05 12:00 |
13:07:12.08 |
-59:58:11.4 |
HIP 64033 |
6.74 |
| 2026-04-06 00:00 |
13:07:03.40 |
-59:57:52.2 |
HIP 64033 |
6.77 |
| 2026-04-06 12:00 |
13:06:54.71 |
-59:57:32.5 |
HIP 64033 |
6.98 |
| 2026-04-07 00:00 |
13:06:46.03 |
-59:57:12.3 |
HIP 64033 |
7.36 |
| 2026-04-07 12:00 |
13:06:37.35 |
-59:56:51.6 |
HIP 64033 |
7.88 |
| 2026-04-08 00:00 |
13:06:28.67 |
-59:56:30.4 |
HIP 64033 |
8.51 |
| 2026-04-08 12:00 |
13:06:19.99 |
-59:56:08.8 |
HIP 64033 |
9.24 |
| 2026-04-09 00:00 |
13:06:11.32 |
-59:55:46.6 |
HIP 64033 |
10.05 |
| 2026-04-09 12:00 |
13:06:02.65 |
-59:55:23.9 |
HIP 64033 |
10.91 |
| 2026-04-10 00:00 |
13:05:53.98 |
-59:55:00.7 |
HIP 64033 |
11.82 |
| 2026-04-10 12:00 |
13:05:45.32 |
-59:54:37.1 |
HIP 64033 |
12.77 |
| 2026-04-11 00:00 |
13:05:36.66 |
-59:54:12.9 |
HIP 64033 |
13.75 |
| 2026-04-11 12:00 |
13:05:28.02 |
-59:53:48.3 |
HIP 64033 |
14.75 |
| 2026-04-12 00:00 |
13:05:19.37 |
-59:53:23.1 |
HIP 64033 |
15.77 |
| 2026-04-12 12:00 |
13:05:10.74 |
-59:52:57.5 |
HIP 64033 |
16.81 |
| 2026-04-13 00:00 |
13:05:02.12 |
-59:52:31.4 |
HIP 63678 |
16.92 |
| 2026-04-13 12:00 |
13:04:53.50 |
-59:52:04.8 |
HIP 63678 |
16.17 |
| 2026-04-14 00:00 |
13:04:44.90 |
-59:51:37.8 |
HIP 63678 |
15.47 |
| 2026-04-14 12:00 |
13:04:36.30 |
-59:51:10.2 |
HIP 63678 |
14.84 |
| 2026-04-15 00:00 |
13:04:27.72 |
-59:50:42.2 |
HIP 63678 |
14.28 |
| 2026-04-15 12:00 |
13:04:19.15 |
-59:50:13.7 |
HIP 63678 |
13.80 |
| 2026-04-16 00:00 |
13:04:10.60 |
-59:49:44.7 |
HIP 63678 |
13.42 |