| 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 |
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) |
| 2026-06-01 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 |
| 2026-06-02 12:00 |
03:19:33.79 |
+39:56:45.8 |
HIP 15355 |
22.33 |
| 2026-06-03 00:00 |
03:19:37.31 |
+39:57:06.0 |
HIP 15355 |
23.07 |
| 2026-06-03 12:00 |
03:19:40.83 |
+39:57:26.3 |
HIP 15355 |
23.82 |
| 2026-06-04 00:00 |
03:19:44.34 |
+39:57:46.6 |
HIP 15355 |
24.56 |
| 2026-06-04 12:00 |
03:19:47.83 |
+39:58:07.0 |
HIP 15355 |
25.31 |
| 2026-06-05 00:00 |
03:19:51.32 |
+39:58:27.6 |
HIP 15355 |
26.05 |
| 2026-06-05 12:00 |
03:19:54.79 |
+39:58:48.2 |
HIP 15355 |
26.80 |
| 2026-06-06 00:00 |
03:19:58.26 |
+39:59:08.9 |
HIP 15355 |
27.54 |
| 2026-06-06 12:00 |
03:20:01.71 |
+39:59:29.7 |
HIP 15355 |
28.28 |
| 2026-06-07 00:00 |
03:20:05.15 |
+39:59:50.6 |
HIP 15355 |
29.02 |
| 2026-06-07 12:00 |
03:20:08.58 |
+40:00:11.5 |
HIP 15355 |
29.76 |
| 2026-06-08 00:00 |
03:20:12.00 |
+40:00:32.6 |
HIP 15355 |
30.50 |
| 2026-06-08 12:00 |
03:20:15.41 |
+40:00:53.7 |
HIP 15355 |
31.24 |
| 2026-06-09 00:00 |
03:20:18.80 |
+40:01:15.0 |
HIP 15355 |
31.98 |
| 2026-06-09 12:00 |
03:20:22.18 |
+40:01:36.3 |
HIP 15355 |
32.71 |
| 2026-06-10 00:00 |
03:20:25.55 |
+40:01:57.6 |
HIP 15355 |
33.45 |
| 2026-06-10 12:00 |
03:20:28.90 |
+40:02:19.1 |
HIP 15355 |
34.18 |
| 2026-06-11 00:00 |
03:20:32.25 |
+40:02:40.7 |
HIP 15716 |
34.56 |
| 2026-06-11 12:00 |
03:20:35.57 |
+40:03:02.3 |
HIP 15716 |
34.44 |
| 2026-06-12 00:00 |
03:20:38.89 |
+40:03:24.0 |
HIP 15716 |
34.34 |
| 2026-06-12 12:00 |
03:20:42.19 |
+40:03:45.7 |
HIP 15716 |
34.26 |
| 2026-06-13 00:00 |
03:20:45.48 |
+40:04:07.6 |
HIP 15716 |
34.19 |
| 2026-06-13 12:00 |
03:20:48.75 |
+40:04:29.5 |
HIP 15716 |
34.15 |
| 2026-06-14 00:00 |
03:20:52.01 |
+40:04:51.5 |
HIP 15716 |
34.12 |
| 2026-06-14 12:00 |
03:20:55.25 |
+40:05:13.6 |
HIP 15716 |
34.11 |
| 2026-06-15 00:00 |
03:20:58.48 |
+40:05:35.7 |
HIP 15716 |
34.12 |
| 2026-06-15 12:00 |
03:21:01.69 |
+40:05:57.9 |
HIP 15716 |
34.14 |
| 2026-06-16 00:00 |
03:21:04.88 |
+40:06:20.2 |
HIP 15716 |
34.19 |
| 2026-06-16 12:00 |
03:21:08.06 |
+40:06:42.6 |
HIP 15716 |
34.25 |
| 2026-06-17 00:00 |
03:21:11.23 |
+40:07:05.0 |
HIP 15716 |
34.33 |
| 2026-06-17 12:00 |
03:21:14.37 |
+40:07:27.4 |
HIP 15716 |
34.42 |
| 2026-06-18 00:00 |
03:21:17.51 |
+40:07:50.0 |
HIP 15716 |
34.53 |
| 2026-06-18 12:00 |
03:21:20.62 |
+40:08:12.6 |
HIP 15716 |
34.66 |
| 2026-06-19 00:00 |
03:21:23.72 |
+40:08:35.2 |
HIP 15716 |
34.81 |
| 2026-06-19 12:00 |
03:21:26.80 |
+40:08:58.0 |
HIP 15871 |
34.94 |
| 2026-06-20 00:00 |
03:21:29.86 |
+40:09:20.7 |
HIP 15871 |
34.44 |
| 2026-06-20 12:00 |
03:21:32.91 |
+40:09:43.6 |
HIP 15871 |
33.94 |
| 2026-06-21 00:00 |
03:21:35.93 |
+40:10:06.5 |
HIP 15871 |
33.46 |
| 2026-06-21 12:00 |
03:21:38.94 |
+40:10:29.4 |
HIP 15871 |
32.98 |
| 2026-06-22 00:00 |
03:21:41.93 |
+40:10:52.4 |
HIP 15871 |
32.52 |