C/2007 Q3 (Siding Spring)
| Parameter |
Value |
| Designation |
C/2007 Q3 (Siding Spring) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2009-10-07T06:29:51.262080Z |
| Orbit solution date (soln_date, UTC) |
2025-07-07T14:12:19Z |
| Obs used |
1341 |
| NEO |
- |
| M1 |
8.800 |
| K1 |
5.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2009-08-20.0000000 |
| e |
1.00023766 |
| q (au) |
2.251688 |
| a (au) |
-9474.438449 |
| i (deg) |
65.650492 |
| Ω (om, deg) |
149.412684 |
| ω (w, deg) |
2.092860 |
| M (ma, deg) |
-0.000052 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.702 + 2.607\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.702 |
| n |
2.607 |
| gf |
1.000 |
| gb |
-0.653 |
| k |
0.991 |
| δ90 |
9.999 |
| 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 |
| 2007-08-25 |
2009-03-15 |
+1.0336 |
-1.397 |
| 2009-03-15 |
2009-05-10 |
+22.4685 |
-12.601 |
| 2009-05-10 |
2009-10-03 |
-25.2771 |
+8.588 |
| 2009-10-10 |
2010-02-28 |
+8.8772 |
-4.011 |
| 2010-02-28 |
2010-06-04 |
+2.9747 |
-2.292 |
| 2010-06-04 |
2010-10-30 |
+3.9111 |
-2.296 |
| 2010-10-30 |
2011-09-25 |
+6.2334 |
-3.591 |
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 |
20:49:08.69 |
+07:33:47.9 |
HIP 102674 |
11.85 |
| 2026-02-03 12:00 |
20:49:12.16 |
+07:33:59.6 |
HIP 102674 |
12.68 |
| 2026-02-04 00:00 |
20:49:15.63 |
+07:34:11.5 |
HIP 102674 |
13.51 |
| 2026-02-04 12:00 |
20:49:19.10 |
+07:34:23.6 |
HIP 102674 |
14.34 |
| 2026-02-05 00:00 |
20:49:22.57 |
+07:34:35.8 |
HIP 102674 |
15.18 |
| 2026-02-05 12:00 |
20:49:26.03 |
+07:34:48.2 |
HIP 102674 |
16.03 |
| 2026-02-06 00:00 |
20:49:29.49 |
+07:35:00.9 |
HIP 102674 |
16.87 |
| 2026-02-06 12:00 |
20:49:32.94 |
+07:35:13.6 |
HIP 102819 |
17.05 |
| 2026-02-07 00:00 |
20:49:36.39 |
+07:35:26.6 |
HIP 102819 |
16.67 |
| 2026-02-07 12:00 |
20:49:39.84 |
+07:35:39.7 |
HIP 102819 |
16.32 |
| 2026-02-08 00:00 |
20:49:43.28 |
+07:35:53.0 |
HIP 102838 |
15.88 |
| 2026-02-08 12:00 |
20:49:46.71 |
+07:36:06.5 |
HIP 102838 |
15.43 |
| 2026-02-09 00:00 |
20:49:50.15 |
+07:36:20.1 |
HIP 102838 |
15.01 |
| 2026-02-09 12:00 |
20:49:53.57 |
+07:36:33.9 |
HIP 102838 |
14.62 |
| 2026-02-10 00:00 |
20:49:56.99 |
+07:36:47.9 |
HIP 102838 |
14.28 |
| 2026-02-10 12:00 |
20:50:00.41 |
+07:37:02.0 |
HIP 102838 |
13.98 |
| 2026-02-11 00:00 |
20:50:03.82 |
+07:37:16.3 |
HIP 102838 |
13.73 |
| 2026-02-11 12:00 |
20:50:07.22 |
+07:37:30.7 |
HIP 102838 |
13.53 |
| 2026-02-12 00:00 |
20:50:10.62 |
+07:37:45.4 |
HIP 102838 |
13.38 |
| 2026-02-12 12:00 |
20:50:14.01 |
+07:38:00.2 |
HIP 102838 |
13.28 |
| 2026-02-13 00:00 |
20:50:17.40 |
+07:38:15.1 |
HIP 102838 |
13.24 |
| 2026-02-13 12:00 |
20:50:20.78 |
+07:38:30.2 |
HIP 102838 |
13.25 |
| 2026-02-14 00:00 |
20:50:24.15 |
+07:38:45.5 |
HIP 102838 |
13.32 |
| 2026-02-14 12:00 |
20:50:27.51 |
+07:39:00.9 |
HIP 102838 |
13.44 |
| 2026-02-15 00:00 |
20:50:30.87 |
+07:39:16.5 |
HIP 102838 |
13.61 |
| 2026-02-15 12:00 |
20:50:34.21 |
+07:39:32.2 |
HIP 102838 |
13.83 |
| 2026-02-16 00:00 |
20:50:37.55 |
+07:39:48.1 |
HIP 102838 |
14.10 |
| 2026-02-16 12:00 |
20:50:40.88 |
+07:40:04.1 |
HIP 102838 |
14.41 |
| 2026-02-17 00:00 |
20:50:44.20 |
+07:40:20.3 |
HIP 102838 |
14.76 |
| 2026-02-17 12:00 |
20:50:47.52 |
+07:40:36.6 |
HIP 102838 |
15.15 |
| 2026-02-18 00:00 |
20:50:50.82 |
+07:40:53.1 |
HIP 102838 |
15.58 |
| 2026-02-18 12:00 |
20:50:54.12 |
+07:41:09.7 |
HIP 102838 |
16.04 |
| 2026-02-19 00:00 |
20:50:57.40 |
+07:41:26.4 |
HIP 102838 |
16.52 |
| 2026-02-19 12:00 |
20:51:00.68 |
+07:41:43.3 |
HIP 102997 |
16.89 |
| 2026-02-20 00:00 |
20:51:03.94 |
+07:42:00.4 |
HIP 102997 |
16.28 |
| 2026-02-20 12:00 |
20:51:07.20 |
+07:42:17.5 |
HIP 102997 |
15.69 |
| 2026-02-21 00:00 |
20:51:10.44 |
+07:42:34.9 |
HIP 102997 |
15.12 |
| 2026-02-21 12:00 |
20:51:13.67 |
+07:42:52.3 |
HIP 102997 |
14.59 |
| 2026-02-22 00:00 |
20:51:16.90 |
+07:43:09.9 |
HIP 102997 |
14.10 |
| 2026-02-22 12:00 |
20:51:20.11 |
+07:43:27.6 |
HIP 102997 |
13.64 |
| 2026-02-23 00:00 |
20:51:23.31 |
+07:43:45.5 |
HIP 102997 |
13.23 |
| 2026-02-23 12:00 |
20:51:26.50 |
+07:44:03.4 |
HIP 102997 |
12.86 |
| 2026-02-24 00:00 |
20:51:29.67 |
+07:44:21.5 |
HIP 102997 |
12.54 |