C/2012 OP (Siding Spring)
| Parameter |
Value |
| Designation |
C/2012 OP (Siding Spring) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2012-12-04T17:50:22.822080Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:19Z |
| Obs used |
100 |
| NEO |
- |
| M1 |
14.400 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2013-01-23.0000000 |
| e |
0.99657940 |
| q (au) |
3.607071 |
| a (au) |
1054.514944 |
| i (deg) |
114.828786 |
| Ω (om, deg) |
267.370339 |
| ω (w, deg) |
351.435364 |
| M (ma, deg) |
0.001418 |
Magnitude
Scatter + Global Linear
$$
M_a = (H_0 + n\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
- |
| n |
- |
| gf |
- |
| gb |
- |
| k |
- |
| δ90 |
- |
| 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) |
| 2026-02-03 00:00 |
08:47:46.39 |
+65:43:11.3 |
HIP 43094 |
17.43 |
| 2026-02-03 12:00 |
08:47:35.31 |
+65:43:15.7 |
HIP 43094 |
17.05 |
| 2026-02-04 00:00 |
08:47:24.25 |
+65:43:19.7 |
HIP 43094 |
16.75 |
| 2026-02-04 12:00 |
08:47:13.20 |
+65:43:23.2 |
HIP 43094 |
16.50 |
| 2026-02-05 00:00 |
08:47:02.16 |
+65:43:26.2 |
HIP 43094 |
16.33 |
| 2026-02-05 12:00 |
08:46:51.13 |
+65:43:28.7 |
HIP 43094 |
16.23 |
| 2026-02-06 00:00 |
08:46:40.12 |
+65:43:30.8 |
HIP 43094 |
16.20 |
| 2026-02-06 12:00 |
08:46:29.12 |
+65:43:32.3 |
HIP 43094 |
16.24 |
| 2026-02-07 00:00 |
08:46:18.13 |
+65:43:33.4 |
HIP 43094 |
16.35 |
| 2026-02-07 12:00 |
08:46:07.17 |
+65:43:34.0 |
HIP 43094 |
16.54 |
| 2026-02-08 00:00 |
08:45:56.22 |
+65:43:34.1 |
HIP 43094 |
16.78 |
| 2026-02-08 12:00 |
08:45:45.29 |
+65:43:33.8 |
HIP 43094 |
17.09 |
| 2026-02-09 00:00 |
08:45:34.37 |
+65:43:32.9 |
HIP 43094 |
17.47 |
| 2026-02-09 12:00 |
08:45:23.48 |
+65:43:31.6 |
HIP 43094 |
17.89 |
| 2026-02-10 00:00 |
08:45:12.61 |
+65:43:29.8 |
HIP 43094 |
18.37 |
| 2026-02-10 12:00 |
08:45:01.77 |
+65:43:27.5 |
HIP 43094 |
18.89 |
| 2026-02-11 00:00 |
08:44:50.94 |
+65:43:24.7 |
HIP 43094 |
19.46 |
| 2026-02-11 12:00 |
08:44:40.15 |
+65:43:21.5 |
HIP 43094 |
20.06 |
| 2026-02-12 00:00 |
08:44:29.37 |
+65:43:17.7 |
HIP 43094 |
20.70 |
| 2026-02-12 12:00 |
08:44:18.63 |
+65:43:13.5 |
HIP 43094 |
21.37 |
| 2026-02-13 00:00 |
08:44:07.91 |
+65:43:08.8 |
HIP 43094 |
22.07 |
| 2026-02-13 12:00 |
08:43:57.22 |
+65:43:03.7 |
HIP 43094 |
22.80 |
| 2026-02-14 00:00 |
08:43:46.56 |
+65:42:58.0 |
HIP 43094 |
23.54 |
| 2026-02-14 12:00 |
08:43:35.92 |
+65:42:51.9 |
HIP 43094 |
24.31 |
| 2026-02-15 00:00 |
08:43:25.33 |
+65:42:45.3 |
HIP 43094 |
25.09 |
| 2026-02-15 12:00 |
08:43:14.76 |
+65:42:38.2 |
HIP 42593 |
24.89 |
| 2026-02-16 00:00 |
08:43:04.22 |
+65:42:30.7 |
HIP 42593 |
24.38 |
| 2026-02-16 12:00 |
08:42:53.73 |
+65:42:22.6 |
HIP 42593 |
23.92 |
| 2026-02-17 00:00 |
08:42:43.26 |
+65:42:14.2 |
HIP 42593 |
23.50 |
| 2026-02-17 12:00 |
08:42:32.83 |
+65:42:05.2 |
HIP 42593 |
23.13 |
| 2026-02-18 00:00 |
08:42:22.44 |
+65:41:55.8 |
HIP 42593 |
22.82 |
| 2026-02-18 12:00 |
08:42:12.09 |
+65:41:45.9 |
HIP 42593 |
22.57 |
| 2026-02-19 00:00 |
08:42:01.78 |
+65:41:35.5 |
HIP 42593 |
22.37 |
| 2026-02-19 12:00 |
08:41:51.51 |
+65:41:24.7 |
HIP 42593 |
22.23 |
| 2026-02-20 00:00 |
08:41:41.27 |
+65:41:13.4 |
HIP 42593 |
22.14 |
| 2026-02-20 12:00 |
08:41:31.08 |
+65:41:01.6 |
HIP 42593 |
22.12 |
| 2026-02-21 00:00 |
08:41:20.94 |
+65:40:49.4 |
HIP 42593 |
22.16 |
| 2026-02-21 12:00 |
08:41:10.83 |
+65:40:36.7 |
HIP 42593 |
22.25 |
| 2026-02-22 00:00 |
08:41:00.77 |
+65:40:23.6 |
HIP 42593 |
22.40 |
| 2026-02-22 12:00 |
08:40:50.76 |
+65:40:10.0 |
HIP 42593 |
22.61 |
| 2026-02-23 00:00 |
08:40:40.79 |
+65:39:55.9 |
HIP 42593 |
22.87 |
| 2026-02-23 12:00 |
08:40:30.87 |
+65:39:41.4 |
HIP 42593 |
23.18 |
| 2026-02-24 00:00 |
08:40:21.00 |
+65:39:26.5 |
HIP 42593 |
23.54 |