C/2012 X2 (PANSTARRS)
| 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) |
| 2026-02-03 00:00 |
18:05:55.70 |
-24:22:53.0 |
HIP 88581 |
10.33 |
| 2026-02-03 12:00 |
18:06:00.71 |
-24:22:47.1 |
HIP 88581 |
11.48 |
| 2026-02-04 00:00 |
18:06:05.68 |
-24:22:41.3 |
HIP 88581 |
12.61 |
| 2026-02-04 12:00 |
18:06:10.62 |
-24:22:35.4 |
HIP 88581 |
13.74 |
| 2026-02-05 00:00 |
18:06:15.53 |
-24:22:29.6 |
HIP 88581 |
14.86 |
| 2026-02-05 12:00 |
18:06:20.41 |
-24:22:23.7 |
HIP 88581 |
15.98 |
| 2026-02-06 00:00 |
18:06:25.25 |
-24:22:17.9 |
HIP 88581 |
17.09 |
| 2026-02-06 12:00 |
18:06:30.05 |
-24:22:12.1 |
HIP 88581 |
18.18 |
| 2026-02-07 00:00 |
18:06:34.83 |
-24:22:06.2 |
HIP 88581 |
19.27 |
| 2026-02-07 12:00 |
18:06:39.56 |
-24:22:00.4 |
HIP 88581 |
20.36 |
| 2026-02-08 00:00 |
18:06:44.26 |
-24:21:54.6 |
HIP 88581 |
21.43 |
| 2026-02-08 12:00 |
18:06:48.93 |
-24:21:48.7 |
HIP 88581 |
22.50 |
| 2026-02-09 00:00 |
18:06:53.55 |
-24:21:42.9 |
HIP 88581 |
23.56 |
| 2026-02-09 12:00 |
18:06:58.15 |
-24:21:37.1 |
HIP 88581 |
24.61 |
| 2026-02-10 00:00 |
18:07:02.70 |
-24:21:31.3 |
HIP 88581 |
25.65 |
| 2026-02-10 12:00 |
18:07:07.22 |
-24:21:25.5 |
HIP 88705 |
25.85 |
| 2026-02-11 00:00 |
18:07:11.70 |
-24:21:19.6 |
HIP 88705 |
26.08 |
| 2026-02-11 12:00 |
18:07:16.14 |
-24:21:13.8 |
HIP 88705 |
26.34 |
| 2026-02-12 00:00 |
18:07:20.55 |
-24:21:08.0 |
HIP 88705 |
26.64 |
| 2026-02-12 12:00 |
18:07:24.91 |
-24:21:02.2 |
HIP 88705 |
26.96 |
| 2026-02-13 00:00 |
18:07:29.24 |
-24:20:56.4 |
HIP 88705 |
27.32 |
| 2026-02-13 12:00 |
18:07:33.53 |
-24:20:50.6 |
HIP 88705 |
27.70 |
| 2026-02-14 00:00 |
18:07:37.78 |
-24:20:44.8 |
HIP 88705 |
28.11 |
| 2026-02-14 12:00 |
18:07:41.99 |
-24:20:39.0 |
HIP 88705 |
28.53 |
| 2026-02-15 00:00 |
18:07:46.16 |
-24:20:33.2 |
HIP 88705 |
28.98 |
| 2026-02-15 12:00 |
18:07:50.29 |
-24:20:27.4 |
HIP 88943 |
29.07 |
| 2026-02-16 00:00 |
18:07:54.38 |
-24:20:21.7 |
HIP 88943 |
28.37 |
| 2026-02-16 12:00 |
18:07:58.43 |
-24:20:15.9 |
HIP 88943 |
27.68 |
| 2026-02-17 00:00 |
18:08:02.43 |
-24:20:10.1 |
HIP 88943 |
27.02 |
| 2026-02-17 12:00 |
18:08:06.40 |
-24:20:04.3 |
HIP 88943 |
26.38 |
| 2026-02-18 00:00 |
18:08:10.33 |
-24:19:58.6 |
HIP 88943 |
25.76 |
| 2026-02-18 12:00 |
18:08:14.21 |
-24:19:52.8 |
HIP 88943 |
25.16 |
| 2026-02-19 00:00 |
18:08:18.05 |
-24:19:47.1 |
HIP 88943 |
24.59 |
| 2026-02-19 12:00 |
18:08:21.85 |
-24:19:41.3 |
HIP 88943 |
24.04 |
| 2026-02-20 00:00 |
18:08:25.61 |
-24:19:35.6 |
HIP 88943 |
23.51 |
| 2026-02-20 12:00 |
18:08:29.32 |
-24:19:29.9 |
HIP 88943 |
23.01 |
| 2026-02-21 00:00 |
18:08:32.99 |
-24:19:24.1 |
HIP 88943 |
22.54 |
| 2026-02-21 12:00 |
18:08:36.62 |
-24:19:18.4 |
HIP 88943 |
22.09 |
| 2026-02-22 00:00 |
18:08:40.20 |
-24:19:12.7 |
HIP 88943 |
21.67 |
| 2026-02-22 12:00 |
18:08:43.74 |
-24:19:07.0 |
HIP 88943 |
21.27 |
| 2026-02-23 00:00 |
18:08:47.24 |
-24:19:01.3 |
HIP 88943 |
20.91 |
| 2026-02-23 12:00 |
18:08:50.69 |
-24:18:55.6 |
HIP 88943 |
20.57 |
| 2026-02-24 00:00 |
18:08:54.10 |
-24:18:49.9 |
HIP 88943 |
20.26 |