| Parameter |
Value |
| Designation |
C/2012 X2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2013-03-31T07:31:18.105600Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:29Z |
| Obs used |
186 |
| NEO |
- |
| M1 |
12.600 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2013-05-10.0000000 |
| e |
0.77049741 |
| q (au) |
4.748158 |
| a (au) |
20.688908 |
| i (deg) |
34.123911 |
| Ω (om, deg) |
271.023294 |
| ω (w, deg) |
215.631135 |
| M (ma, deg) |
0.415663 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.863 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.863 |
| n |
2.000 |
| gf |
0.969 |
| gb |
-1.000 |
| k |
1.000 |
| δ90 |
9.860 |
| 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 |
| 2012-01-11 |
2013-03-14 |
+4.8190 |
-2.841 |
| 2013-03-31 |
2014-04-24 |
-8.5260 |
+5.540 |
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 |
18:04:54.53 |
-24:02:18.1 |
HIP 88581 |
21.92 |
| 2026-06-01 12:00 |
18:04:49.49 |
-24:02:12.7 |
HIP 88581 |
22.23 |
| 2026-06-02 00:00 |
18:04:44.43 |
-24:02:07.2 |
HIP 88496 |
22.37 |
| 2026-06-02 12:00 |
18:04:39.34 |
-24:02:01.7 |
HIP 88496 |
22.14 |
| 2026-06-03 00:00 |
18:04:34.24 |
-24:01:56.2 |
HIP 88469 |
21.89 |
| 2026-06-03 12:00 |
18:04:29.13 |
-24:01:50.7 |
HIP 88469 |
21.49 |
| 2026-06-04 00:00 |
18:04:23.99 |
-24:01:45.2 |
HIP 88469 |
21.15 |
| 2026-06-04 12:00 |
18:04:18.84 |
-24:01:39.6 |
HIP 88469 |
20.87 |
| 2026-06-05 00:00 |
18:04:13.68 |
-24:01:34.1 |
HIP 88469 |
20.65 |
| 2026-06-05 12:00 |
18:04:08.49 |
-24:01:28.5 |
HIP 88469 |
20.50 |
| 2026-06-06 00:00 |
18:04:03.30 |
-24:01:22.9 |
HIP 88469 |
20.41 |
| 2026-06-06 12:00 |
18:03:58.08 |
-24:01:17.3 |
HIP 88469 |
20.40 |
| 2026-06-07 00:00 |
18:03:52.86 |
-24:01:11.7 |
HIP 88469 |
20.45 |
| 2026-06-07 12:00 |
18:03:47.61 |
-24:01:06.0 |
HIP 88380 |
20.43 |
| 2026-06-08 00:00 |
18:03:42.36 |
-24:01:00.4 |
HIP 88380 |
19.77 |
| 2026-06-08 12:00 |
18:03:37.09 |
-24:00:54.7 |
HIP 88380 |
19.16 |
| 2026-06-09 00:00 |
18:03:31.81 |
-24:00:49.0 |
HIP 88380 |
18.61 |
| 2026-06-09 12:00 |
18:03:26.52 |
-24:00:43.3 |
HIP 88380 |
18.13 |
| 2026-06-10 00:00 |
18:03:21.22 |
-24:00:37.5 |
HIP 88380 |
17.71 |
| 2026-06-10 12:00 |
18:03:15.90 |
-24:00:31.8 |
HIP 88380 |
17.36 |
| 2026-06-11 00:00 |
18:03:10.57 |
-24:00:26.0 |
HIP 88380 |
17.10 |
| 2026-06-11 12:00 |
18:03:05.24 |
-24:00:20.2 |
HIP 88380 |
16.92 |
| 2026-06-12 00:00 |
18:02:59.89 |
-24:00:14.4 |
HIP 88380 |
16.83 |
| 2026-06-12 12:00 |
18:02:54.54 |
-24:00:08.6 |
HIP 88380 |
16.82 |
| 2026-06-13 00:00 |
18:02:49.17 |
-24:00:02.7 |
HIP 88380 |
16.91 |
| 2026-06-13 12:00 |
18:02:43.80 |
-23:59:56.9 |
HIP 88380 |
17.08 |
| 2026-06-14 00:00 |
18:02:38.42 |
-23:59:51.0 |
HIP 88380 |
17.34 |
| 2026-06-14 12:00 |
18:02:33.04 |
-23:59:45.1 |
HIP 88380 |
17.68 |
| 2026-06-15 00:00 |
18:02:27.64 |
-23:59:39.2 |
HIP 88380 |
18.10 |
| 2026-06-15 12:00 |
18:02:22.24 |
-23:59:33.3 |
HIP 88380 |
18.60 |
| 2026-06-16 00:00 |
18:02:16.84 |
-23:59:27.3 |
HIP 88380 |
19.16 |
| 2026-06-16 12:00 |
18:02:11.43 |
-23:59:21.4 |
HIP 88380 |
19.78 |
| 2026-06-17 00:00 |
18:02:06.01 |
-23:59:15.4 |
HIP 88380 |
20.46 |
| 2026-06-17 12:00 |
18:02:00.60 |
-23:59:09.4 |
HIP 88380 |
21.19 |
| 2026-06-18 00:00 |
18:01:55.17 |
-23:59:03.4 |
HIP 88380 |
21.97 |
| 2026-06-18 12:00 |
18:01:49.75 |
-23:58:57.3 |
HIP 88380 |
22.79 |
| 2026-06-19 00:00 |
18:01:44.32 |
-23:58:51.3 |
HIP 88380 |
23.65 |
| 2026-06-19 12:00 |
18:01:38.89 |
-23:58:45.2 |
HIP 88380 |
24.54 |
| 2026-06-20 00:00 |
18:01:33.46 |
-23:58:39.1 |
HIP 88380 |
25.46 |
| 2026-06-20 12:00 |
18:01:28.03 |
-23:58:33.0 |
HIP 88116 |
24.89 |
| 2026-06-21 00:00 |
18:01:22.60 |
-23:58:26.9 |
HIP 88116 |
23.71 |
| 2026-06-21 12:00 |
18:01:17.17 |
-23:58:20.7 |
HIP 88116 |
22.53 |
| 2026-06-22 00:00 |
18:01:11.74 |
-23:58:14.6 |
HIP 88116 |
21.36 |