| Parameter |
Value |
| Designation |
C/2012 A1 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2013-11-29T15:21:03.746880Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:59Z |
| Obs used |
322 |
| NEO |
- |
| M1 |
10.100 |
| K1 |
5.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2012-12-26.0000000 |
| e |
1.00119496 |
| q (au) |
7.604434 |
| a (au) |
-6363.768778 |
| i (deg) |
120.900017 |
| Ω (om, deg) |
277.972039 |
| ω (w, deg) |
191.758696 |
| M (ma, deg) |
-0.000657 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.521 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.521 |
| n |
2.000 |
| gf |
0.822 |
| gb |
-0.955 |
| k |
1.000 |
| δ90 |
2.925 |
| 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) |
| 2026-09-20 00:00 |
22:27:31.93 |
-59:37:58.1 |
HIP 110973 |
26.68 |
| 2026-09-20 12:00 |
22:27:22.50 |
-59:37:49.1 |
HIP 110973 |
27.08 |
| 2026-09-21 00:00 |
22:27:13.10 |
-59:37:39.7 |
HIP 110973 |
27.52 |
| 2026-09-21 12:00 |
22:27:03.74 |
-59:37:29.7 |
HIP 110973 |
27.99 |
| 2026-09-22 00:00 |
22:26:54.41 |
-59:37:19.1 |
HIP 110973 |
28.50 |
| 2026-09-22 12:00 |
22:26:45.12 |
-59:37:08.1 |
HIP 110973 |
29.03 |
| 2026-09-23 00:00 |
22:26:35.87 |
-59:36:56.5 |
HIP 110973 |
29.60 |
| 2026-09-23 12:00 |
22:26:26.66 |
-59:36:44.4 |
HIP 110973 |
30.20 |
| 2026-09-24 00:00 |
22:26:17.49 |
-59:36:31.8 |
HIP 110973 |
30.81 |
| 2026-09-24 12:00 |
22:26:08.35 |
-59:36:18.7 |
HIP 110973 |
31.46 |
| 2026-09-25 00:00 |
22:25:59.26 |
-59:36:05.1 |
HIP 110973 |
32.12 |
| 2026-09-25 12:00 |
22:25:50.21 |
-59:35:51.0 |
HIP 110973 |
32.80 |
| 2026-09-26 00:00 |
22:25:41.19 |
-59:35:36.4 |
HIP 110973 |
33.50 |
| 2026-09-26 12:00 |
22:25:32.23 |
-59:35:21.2 |
HIP 110973 |
34.22 |
| 2026-09-27 00:00 |
22:25:23.30 |
-59:35:05.6 |
HIP 110973 |
34.95 |
| 2026-09-27 12:00 |
22:25:14.42 |
-59:34:49.4 |
HIP 110402 |
34.55 |
| 2026-09-28 00:00 |
22:25:05.58 |
-59:34:32.8 |
HIP 110402 |
33.89 |
| 2026-09-28 12:00 |
22:24:56.78 |
-59:34:15.7 |
HIP 110402 |
33.26 |
| 2026-09-29 00:00 |
22:24:48.03 |
-59:33:58.0 |
HIP 110499 |
32.52 |
| 2026-09-29 12:00 |
22:24:39.33 |
-59:33:39.9 |
HIP 110499 |
31.79 |
| 2026-09-30 00:00 |
22:24:30.67 |
-59:33:21.2 |
HIP 110499 |
31.08 |
| 2026-09-30 12:00 |
22:24:22.06 |
-59:33:02.1 |
HIP 110499 |
30.39 |
| 2026-10-01 00:00 |
22:24:13.50 |
-59:32:42.5 |
HIP 110499 |
29.73 |
| 2026-10-01 12:00 |
22:24:04.98 |
-59:32:22.4 |
HIP 110499 |
29.08 |
| 2026-10-02 00:00 |
22:23:56.52 |
-59:32:01.8 |
HIP 110499 |
28.46 |
| 2026-10-02 12:00 |
22:23:48.10 |
-59:31:40.7 |
HIP 110499 |
27.87 |
| 2026-10-03 00:00 |
22:23:39.73 |
-59:31:19.2 |
HIP 110499 |
27.30 |
| 2026-10-03 12:00 |
22:23:31.42 |
-59:30:57.1 |
HIP 110499 |
26.77 |
| 2026-10-04 00:00 |
22:23:23.16 |
-59:30:34.6 |
HIP 110499 |
26.26 |
| 2026-10-04 12:00 |
22:23:14.94 |
-59:30:11.6 |
HIP 110499 |
25.78 |
| 2026-10-05 00:00 |
22:23:06.78 |
-59:29:48.1 |
HIP 110499 |
25.33 |
| 2026-10-05 12:00 |
22:22:58.68 |
-59:29:24.1 |
HIP 110499 |
24.92 |
| 2026-10-06 00:00 |
22:22:50.63 |
-59:28:59.7 |
HIP 110499 |
24.55 |
| 2026-10-06 12:00 |
22:22:42.63 |
-59:28:34.8 |
HIP 110499 |
24.21 |
| 2026-10-07 00:00 |
22:22:34.68 |
-59:28:09.5 |
HIP 110499 |
23.91 |
| 2026-10-07 12:00 |
22:22:26.80 |
-59:27:43.6 |
HIP 110499 |
23.64 |
| 2026-10-08 00:00 |
22:22:18.97 |
-59:27:17.3 |
HIP 110499 |
23.42 |
| 2026-10-08 12:00 |
22:22:11.19 |
-59:26:50.6 |
HIP 110206 |
22.94 |
| 2026-10-09 00:00 |
22:22:03.47 |
-59:26:23.4 |
HIP 110206 |
21.86 |
| 2026-10-09 12:00 |
22:21:55.81 |
-59:25:55.7 |
HIP 110206 |
20.79 |
| 2026-10-10 00:00 |
22:21:48.21 |
-59:25:27.6 |
HIP 110206 |
19.71 |
| 2026-10-10 12:00 |
22:21:40.67 |
-59:24:59.0 |
HIP 110206 |
18.65 |
| 2026-10-11 00:00 |
22:21:33.19 |
-59:24:30.0 |
HIP 110206 |
17.58 |