| Parameter |
Value |
| Designation |
C/2004 T3 (Siding Spring) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2003-04-15T07:34:17.973120Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:43Z |
| Obs used |
106 |
| NEO |
- |
| M1 |
6.300 |
| K1 |
7.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2005-02-13.0000000 |
| e |
0.99848905 |
| q (au) |
8.864365 |
| a (au) |
5866.764568 |
| i (deg) |
71.964320 |
| Ω (om, deg) |
50.354596 |
| ω (w, deg) |
259.686905 |
| M (ma, deg) |
0.001469 |
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 |
1.000 |
| gb |
-1.000 |
| 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) |
| 2026-05-12 00:00 |
03:16:55.87 |
+39:43:59.2 |
HIP 15355 |
12.27 |
| 2026-05-12 12:00 |
03:16:59.61 |
+39:44:14.6 |
HIP 15355 |
11.56 |
| 2026-05-13 00:00 |
03:17:03.35 |
+39:44:30.0 |
HIP 15355 |
10.86 |
| 2026-05-13 12:00 |
03:17:07.09 |
+39:44:45.6 |
HIP 15355 |
10.17 |
| 2026-05-14 00:00 |
03:17:10.83 |
+39:45:01.3 |
HIP 15355 |
9.49 |
| 2026-05-14 12:00 |
03:17:14.57 |
+39:45:17.2 |
HIP 15355 |
8.82 |
| 2026-05-15 00:00 |
03:17:18.31 |
+39:45:33.2 |
HIP 15355 |
8.18 |
| 2026-05-15 12:00 |
03:17:22.05 |
+39:45:49.3 |
HIP 15355 |
7.55 |
| 2026-05-16 00:00 |
03:17:25.78 |
+39:46:05.5 |
HIP 15355 |
6.96 |
| 2026-05-16 12:00 |
03:17:29.52 |
+39:46:21.8 |
HIP 15355 |
6.40 |
| 2026-05-17 00:00 |
03:17:33.25 |
+39:46:38.3 |
HIP 15355 |
5.89 |
| 2026-05-17 12:00 |
03:17:36.98 |
+39:46:54.9 |
HIP 15355 |
5.45 |
| 2026-05-18 00:00 |
03:17:40.71 |
+39:47:11.7 |
HIP 15355 |
5.09 |
| 2026-05-18 12:00 |
03:17:44.43 |
+39:47:28.5 |
HIP 15355 |
4.82 |
| 2026-05-19 00:00 |
03:17:48.16 |
+39:47:45.5 |
HIP 15355 |
4.67 |
| 2026-05-19 12:00 |
03:17:51.88 |
+39:48:02.5 |
HIP 15355 |
4.65 |
| 2026-05-20 00:00 |
03:17:55.59 |
+39:48:19.8 |
HIP 15355 |
4.75 |
| 2026-05-20 12:00 |
03:17:59.31 |
+39:48:37.1 |
HIP 15355 |
4.97 |
| 2026-05-21 00:00 |
03:18:03.02 |
+39:48:54.5 |
HIP 15355 |
5.30 |
| 2026-05-21 12:00 |
03:18:06.72 |
+39:49:12.1 |
HIP 15355 |
5.72 |
| 2026-05-22 00:00 |
03:18:10.42 |
+39:49:29.7 |
HIP 15355 |
6.21 |
| 2026-05-22 12:00 |
03:18:14.12 |
+39:49:47.5 |
HIP 15355 |
6.75 |
| 2026-05-23 00:00 |
03:18:17.81 |
+39:50:05.4 |
HIP 15355 |
7.33 |
| 2026-05-23 12:00 |
03:18:21.49 |
+39:50:23.4 |
HIP 15355 |
7.94 |
| 2026-05-24 00:00 |
03:18:25.17 |
+39:50:41.6 |
HIP 15355 |
8.58 |
| 2026-05-24 12:00 |
03:18:28.85 |
+39:50:59.8 |
HIP 15355 |
9.25 |
| 2026-05-25 00:00 |
03:18:32.52 |
+39:51:18.1 |
HIP 15355 |
9.92 |
| 2026-05-25 12:00 |
03:18:36.18 |
+39:51:36.6 |
HIP 15355 |
10.61 |
| 2026-05-26 00:00 |
03:18:39.84 |
+39:51:55.1 |
HIP 15355 |
11.31 |
| 2026-05-26 12:00 |
03:18:43.49 |
+39:52:13.8 |
HIP 15355 |
12.02 |
| 2026-05-27 00:00 |
03:18:47.13 |
+39:52:32.6 |
HIP 15355 |
12.74 |
| 2026-05-27 12:00 |
03:18:50.77 |
+39:52:51.4 |
HIP 15355 |
13.46 |
| 2026-05-28 00:00 |
03:18:54.39 |
+39:53:10.4 |
HIP 15355 |
14.19 |
| 2026-05-28 12:00 |
03:18:58.02 |
+39:53:29.5 |
HIP 15355 |
14.92 |
| 2026-05-29 00:00 |
03:19:01.63 |
+39:53:48.7 |
HIP 15355 |
15.65 |
| 2026-05-29 12:00 |
03:19:05.24 |
+39:54:08.0 |
HIP 15355 |
16.39 |
| 2026-05-30 00:00 |
03:19:08.84 |
+39:54:27.4 |
HIP 15355 |
17.13 |
| 2026-05-30 12:00 |
03:19:12.43 |
+39:54:46.9 |
HIP 15355 |
17.87 |
| 2026-05-31 00:00 |
03:19:16.01 |
+39:55:06.4 |
HIP 15355 |
18.61 |
| 2026-05-31 12:00 |
03:19:19.58 |
+39:55:26.1 |
HIP 15355 |
19.35 |
| 2026-06-01 00:00 |
03:19:23.15 |
+39:55:45.9 |
HIP 15355 |
20.10 |
| 2026-06-01 12:00 |
03:19:26.70 |
+39:56:05.8 |
HIP 15355 |
20.84 |
| 2026-06-02 00:00 |
03:19:30.25 |
+39:56:25.8 |
HIP 15355 |
21.58 |