| Parameter |
Value |
| Designation |
C/2004 T3 (Siding Spring) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2003-04-15T07:36:04.478400Z |
| Orbit solution date (soln_date, UTC) |
2026-06-09T11:12:22Z |
| Obs used |
110 |
| NEO |
- |
| M1 |
6.400 |
| K1 |
7.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2005-02-10.0000000 |
| e |
0.99847370 |
| q (au) |
8.864377 |
| a (au) |
5807.750491 |
| i (deg) |
71.964273 |
| Ω (om, deg) |
50.354719 |
| ω (w, deg) |
259.687076 |
| M (ma, deg) |
0.001485 |
Magnitude
Scatter + Global Linear
$$
M_a = (-1.455 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
-1.455 |
| n |
6.000 |
| gf |
0.999 |
| gb |
-0.869 |
| k |
1.000 |
| δ90 |
10.000 |
| 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) |
| 2026-07-29 00:00 |
03:24:20.46 |
+40:40:28.1 |
HIP 15895 |
6.95 |
| 2026-07-29 12:00 |
03:24:21.61 |
+40:40:52.0 |
HIP 15895 |
6.51 |
| 2026-07-30 00:00 |
03:24:22.72 |
+40:41:15.8 |
HIP 15895 |
6.08 |
| 2026-07-30 12:00 |
03:24:23.80 |
+40:41:39.6 |
HIP 15895 |
5.65 |
| 2026-07-31 00:00 |
03:24:24.85 |
+40:42:03.4 |
HIP 15895 |
5.23 |
| 2026-07-31 12:00 |
03:24:25.87 |
+40:42:27.1 |
HIP 15895 |
4.82 |
| 2026-08-01 00:00 |
03:24:26.86 |
+40:42:50.7 |
HIP 15895 |
4.42 |
| 2026-08-01 12:00 |
03:24:27.82 |
+40:43:14.4 |
HIP 15895 |
4.04 |
| 2026-08-02 00:00 |
03:24:28.75 |
+40:43:37.9 |
HIP 15895 |
3.67 |
| 2026-08-02 12:00 |
03:24:29.65 |
+40:44:01.5 |
HIP 15895 |
3.32 |
| 2026-08-03 00:00 |
03:24:30.52 |
+40:44:25.0 |
HIP 15895 |
2.99 |
| 2026-08-03 12:00 |
03:24:31.36 |
+40:44:48.5 |
HIP 15895 |
2.70 |
| 2026-08-04 00:00 |
03:24:32.16 |
+40:45:11.9 |
HIP 15895 |
2.46 |
| 2026-08-04 12:00 |
03:24:32.94 |
+40:45:35.2 |
HIP 15895 |
2.27 |
| 2026-08-05 00:00 |
03:24:33.68 |
+40:45:58.5 |
HIP 15895 |
2.15 |
| 2026-08-05 12:00 |
03:24:34.40 |
+40:46:21.8 |
HIP 15895 |
2.11 |
| 2026-08-06 00:00 |
03:24:35.08 |
+40:46:45.0 |
HIP 15895 |
2.16 |
| 2026-08-06 12:00 |
03:24:35.73 |
+40:47:08.2 |
HIP 15895 |
2.28 |
| 2026-08-07 00:00 |
03:24:36.35 |
+40:47:31.3 |
HIP 15895 |
2.47 |
| 2026-08-07 12:00 |
03:24:36.94 |
+40:47:54.3 |
HIP 15895 |
2.71 |
| 2026-08-08 00:00 |
03:24:37.49 |
+40:48:17.3 |
HIP 15895 |
2.99 |
| 2026-08-08 12:00 |
03:24:38.02 |
+40:48:40.2 |
HIP 15895 |
3.29 |
| 2026-08-09 00:00 |
03:24:38.51 |
+40:49:03.1 |
HIP 15895 |
3.61 |
| 2026-08-09 12:00 |
03:24:38.97 |
+40:49:25.9 |
HIP 15895 |
3.94 |
| 2026-08-10 00:00 |
03:24:39.40 |
+40:49:48.7 |
HIP 15895 |
4.29 |
| 2026-08-10 12:00 |
03:24:39.80 |
+40:50:11.3 |
HIP 15895 |
4.64 |
| 2026-08-11 00:00 |
03:24:40.16 |
+40:50:34.0 |
HIP 15895 |
4.99 |
| 2026-08-11 12:00 |
03:24:40.49 |
+40:50:56.5 |
HIP 15895 |
5.35 |
| 2026-08-12 00:00 |
03:24:40.79 |
+40:51:19.0 |
HIP 15895 |
5.72 |
| 2026-08-12 12:00 |
03:24:41.06 |
+40:51:41.4 |
HIP 15895 |
6.08 |
| 2026-08-13 00:00 |
03:24:41.29 |
+40:52:03.8 |
HIP 15895 |
6.45 |
| 2026-08-13 12:00 |
03:24:41.50 |
+40:52:26.0 |
HIP 15895 |
6.81 |
| 2026-08-14 00:00 |
03:24:41.67 |
+40:52:48.2 |
HIP 15895 |
7.18 |
| 2026-08-14 12:00 |
03:24:41.80 |
+40:53:10.4 |
HIP 15895 |
7.54 |
| 2026-08-15 00:00 |
03:24:41.91 |
+40:53:32.4 |
HIP 15895 |
7.91 |
| 2026-08-15 12:00 |
03:24:41.98 |
+40:53:54.4 |
HIP 15944 |
7.82 |
| 2026-08-16 00:00 |
03:24:42.02 |
+40:54:16.3 |
HIP 15944 |
7.67 |
| 2026-08-16 12:00 |
03:24:42.03 |
+40:54:38.1 |
HIP 15944 |
7.53 |
| 2026-08-17 00:00 |
03:24:42.00 |
+40:54:59.8 |
HIP 15944 |
7.42 |
| 2026-08-17 12:00 |
03:24:41.94 |
+40:55:21.5 |
HIP 15944 |
7.33 |
| 2026-08-18 00:00 |
03:24:41.85 |
+40:55:43.0 |
HIP 15944 |
7.27 |
| 2026-08-18 12:00 |
03:24:41.73 |
+40:56:04.5 |
HIP 15944 |
7.23 |
| 2026-08-19 00:00 |
03:24:41.57 |
+40:56:25.9 |
HIP 15944 |
7.21 |