| Parameter |
Value |
| Designation |
C/2008 C1 (Chen-Gao) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2008-04-16T20:25:39.135360Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:16Z |
| Obs used |
754 |
| NEO |
- |
| M1 |
13.800 |
| K1 |
5.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2008-03-06.0000000 |
| e |
1.00000066 |
| q (au) |
1.262346 |
| a (au) |
-1909647.271764 |
| i (deg) |
61.784520 |
| Ω (om, deg) |
307.782377 |
| ω (w, deg) |
180.928392 |
| M (ma, deg) |
-0.000000 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.986 + 2.066\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.986 |
| n |
2.066 |
| gf |
1.000 |
| gb |
-0.500 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2008-01-30 |
2008-04-16 |
+12.3117 |
-3.108 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
20:17:07.89 |
-38:16:54.8 |
HIP 100119 |
20.87 |
| 2026-07-29 12:00 |
20:17:04.01 |
-38:17:01.8 |
HIP 100119 |
21.57 |
| 2026-07-30 00:00 |
20:17:00.14 |
-38:17:08.5 |
HIP 100119 |
22.27 |
| 2026-07-30 12:00 |
20:16:56.27 |
-38:17:15.2 |
HIP 99882 |
22.31 |
| 2026-07-31 00:00 |
20:16:52.41 |
-38:17:21.7 |
HIP 99882 |
21.99 |
| 2026-07-31 12:00 |
20:16:48.55 |
-38:17:28.0 |
HIP 99882 |
21.69 |
| 2026-08-01 00:00 |
20:16:44.69 |
-38:17:34.2 |
HIP 99882 |
21.41 |
| 2026-08-01 12:00 |
20:16:40.84 |
-38:17:40.2 |
HIP 99882 |
21.16 |
| 2026-08-02 00:00 |
20:16:36.99 |
-38:17:46.2 |
HIP 99882 |
20.92 |
| 2026-08-02 12:00 |
20:16:33.15 |
-38:17:51.9 |
HIP 99882 |
20.72 |
| 2026-08-03 00:00 |
20:16:29.31 |
-38:17:57.5 |
HIP 99882 |
20.53 |
| 2026-08-03 12:00 |
20:16:25.48 |
-38:18:03.0 |
HIP 99882 |
20.37 |
| 2026-08-04 00:00 |
20:16:21.65 |
-38:18:08.3 |
HIP 99882 |
20.24 |
| 2026-08-04 12:00 |
20:16:17.83 |
-38:18:13.5 |
HIP 99882 |
20.13 |
| 2026-08-05 00:00 |
20:16:14.01 |
-38:18:18.5 |
HIP 99882 |
20.05 |
| 2026-08-05 12:00 |
20:16:10.21 |
-38:18:23.4 |
HIP 99882 |
19.99 |
| 2026-08-06 00:00 |
20:16:06.40 |
-38:18:28.1 |
HIP 99882 |
19.96 |
| 2026-08-06 12:00 |
20:16:02.61 |
-38:18:32.7 |
HIP 99882 |
19.96 |
| 2026-08-07 00:00 |
20:15:58.82 |
-38:18:37.1 |
HIP 99882 |
19.98 |
| 2026-08-07 12:00 |
20:15:55.04 |
-38:18:41.4 |
HIP 99882 |
20.02 |
| 2026-08-08 00:00 |
20:15:51.27 |
-38:18:45.5 |
HIP 99882 |
20.09 |
| 2026-08-08 12:00 |
20:15:47.51 |
-38:18:49.4 |
HIP 99734 |
19.99 |
| 2026-08-09 00:00 |
20:15:43.76 |
-38:18:53.3 |
HIP 99734 |
19.32 |
| 2026-08-09 12:00 |
20:15:40.01 |
-38:18:56.9 |
HIP 99734 |
18.65 |
| 2026-08-10 00:00 |
20:15:36.28 |
-38:19:00.4 |
HIP 99734 |
18.00 |
| 2026-08-10 12:00 |
20:15:32.55 |
-38:19:03.8 |
HIP 99734 |
17.35 |
| 2026-08-11 00:00 |
20:15:28.83 |
-38:19:07.0 |
HIP 99734 |
16.70 |
| 2026-08-11 12:00 |
20:15:25.13 |
-38:19:10.0 |
HIP 99734 |
16.07 |
| 2026-08-12 00:00 |
20:15:21.43 |
-38:19:12.9 |
HIP 99734 |
15.44 |
| 2026-08-12 12:00 |
20:15:17.75 |
-38:19:15.6 |
HIP 99734 |
14.83 |
| 2026-08-13 00:00 |
20:15:14.07 |
-38:19:18.2 |
HIP 99734 |
14.23 |
| 2026-08-13 12:00 |
20:15:10.41 |
-38:19:20.6 |
HIP 99734 |
13.63 |
| 2026-08-14 00:00 |
20:15:06.76 |
-38:19:22.8 |
HIP 99734 |
13.05 |
| 2026-08-14 12:00 |
20:15:03.12 |
-38:19:24.9 |
HIP 99734 |
12.49 |
| 2026-08-15 00:00 |
20:14:59.50 |
-38:19:26.9 |
HIP 99734 |
11.94 |
| 2026-08-15 12:00 |
20:14:55.89 |
-38:19:28.7 |
HIP 99734 |
11.41 |
| 2026-08-16 00:00 |
20:14:52.29 |
-38:19:30.3 |
HIP 99734 |
10.91 |
| 2026-08-16 12:00 |
20:14:48.70 |
-38:19:31.8 |
HIP 99734 |
10.42 |
| 2026-08-17 00:00 |
20:14:45.13 |
-38:19:33.1 |
HIP 99734 |
9.96 |
| 2026-08-17 12:00 |
20:14:41.57 |
-38:19:34.2 |
HIP 99734 |
9.53 |
| 2026-08-18 00:00 |
20:14:38.03 |
-38:19:35.2 |
HIP 99734 |
9.13 |
| 2026-08-18 12:00 |
20:14:34.50 |
-38:19:36.1 |
HIP 99734 |
8.77 |
| 2026-08-19 00:00 |
20:14:30.98 |
-38:19:36.7 |
HIP 99734 |
8.45 |