| 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
$$
M_a = (10.861 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.861 |
| n |
2.000 |
| gf |
0.970 |
| gb |
-1.000 |
| k |
1.000 |
| δ90 |
9.954 |
| 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 |
-2.842 |
| 2013-03-31 |
2014-04-24 |
-8.5263 |
+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) |
| 2026-05-12 00:00 |
18:07:56.00 |
-24:05:44.4 |
HIP 88943 |
19.73 |
| 2026-05-12 12:00 |
18:07:52.06 |
-24:05:39.5 |
HIP 88705 |
19.97 |
| 2026-05-13 00:00 |
18:07:48.08 |
-24:05:34.5 |
HIP 88705 |
19.12 |
| 2026-05-13 12:00 |
18:07:44.06 |
-24:05:29.5 |
HIP 88705 |
18.27 |
| 2026-05-14 00:00 |
18:07:40.01 |
-24:05:24.6 |
HIP 88705 |
17.43 |
| 2026-05-14 12:00 |
18:07:35.93 |
-24:05:19.6 |
HIP 88705 |
16.58 |
| 2026-05-15 00:00 |
18:07:31.81 |
-24:05:14.6 |
HIP 88705 |
15.74 |
| 2026-05-15 12:00 |
18:07:27.66 |
-24:05:09.6 |
HIP 88705 |
14.91 |
| 2026-05-16 00:00 |
18:07:23.48 |
-24:05:04.6 |
HIP 88705 |
14.08 |
| 2026-05-16 12:00 |
18:07:19.26 |
-24:04:59.6 |
HIP 88705 |
13.26 |
| 2026-05-17 00:00 |
18:07:15.01 |
-24:04:54.6 |
HIP 88705 |
12.47 |
| 2026-05-17 12:00 |
18:07:10.73 |
-24:04:49.5 |
HIP 88705 |
11.69 |
| 2026-05-18 00:00 |
18:07:06.42 |
-24:04:44.5 |
HIP 88705 |
10.94 |
| 2026-05-18 12:00 |
18:07:02.07 |
-24:04:39.5 |
HIP 88705 |
10.22 |
| 2026-05-19 00:00 |
18:06:57.69 |
-24:04:34.4 |
HIP 88705 |
9.56 |
| 2026-05-19 12:00 |
18:06:53.29 |
-24:04:29.3 |
HIP 88705 |
8.95 |
| 2026-05-20 00:00 |
18:06:48.85 |
-24:04:24.2 |
HIP 88705 |
8.41 |
| 2026-05-20 12:00 |
18:06:44.39 |
-24:04:19.1 |
HIP 88705 |
7.97 |
| 2026-05-21 00:00 |
18:06:39.89 |
-24:04:14.0 |
HIP 88705 |
7.64 |
| 2026-05-21 12:00 |
18:06:35.37 |
-24:04:08.9 |
HIP 88705 |
7.44 |
| 2026-05-22 00:00 |
18:06:30.82 |
-24:04:03.8 |
HIP 88705 |
7.38 |
| 2026-05-22 12:00 |
18:06:26.24 |
-24:03:58.6 |
HIP 88705 |
7.46 |
| 2026-05-23 00:00 |
18:06:21.63 |
-24:03:53.4 |
HIP 88705 |
7.70 |
| 2026-05-23 12:00 |
18:06:17.00 |
-24:03:48.3 |
HIP 88705 |
8.06 |
| 2026-05-24 00:00 |
18:06:12.34 |
-24:03:43.1 |
HIP 88705 |
8.55 |
| 2026-05-24 12:00 |
18:06:07.65 |
-24:03:37.9 |
HIP 88705 |
9.14 |
| 2026-05-25 00:00 |
18:06:02.94 |
-24:03:32.7 |
HIP 88705 |
9.82 |
| 2026-05-25 12:00 |
18:05:58.21 |
-24:03:27.4 |
HIP 88705 |
10.57 |
| 2026-05-26 00:00 |
18:05:53.44 |
-24:03:22.2 |
HIP 88705 |
11.38 |
| 2026-05-26 12:00 |
18:05:48.66 |
-24:03:16.9 |
HIP 88705 |
12.23 |
| 2026-05-27 00:00 |
18:05:43.85 |
-24:03:11.7 |
HIP 88705 |
13.13 |
| 2026-05-27 12:00 |
18:05:39.02 |
-24:03:06.4 |
HIP 88705 |
14.06 |
| 2026-05-28 00:00 |
18:05:34.16 |
-24:03:01.1 |
HIP 88705 |
15.02 |
| 2026-05-28 12:00 |
18:05:29.28 |
-24:02:55.8 |
HIP 88705 |
16.00 |
| 2026-05-29 00:00 |
18:05:24.38 |
-24:02:50.4 |
HIP 88705 |
17.01 |
| 2026-05-29 12:00 |
18:05:19.46 |
-24:02:45.1 |
HIP 88705 |
18.03 |
| 2026-05-30 00:00 |
18:05:14.51 |
-24:02:39.7 |
HIP 88705 |
19.07 |
| 2026-05-30 12:00 |
18:05:09.55 |
-24:02:34.3 |
HIP 88705 |
20.13 |
| 2026-05-31 00:00 |
18:05:04.56 |
-24:02:28.9 |
HIP 88705 |
21.19 |
| 2026-05-31 12:00 |
18:04:59.56 |
-24:02:23.5 |
HIP 88581 |
21.67 |
| 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 |