C/2008 C1 (Chen-Gao)
| 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 |
0.999 |
| gb |
-0.998 |
| 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) |
| 2026-02-03 00:00 |
20:18:48.96 |
-37:26:19.6 |
HIP 99949 |
25.36 |
| 2026-02-03 12:00 |
20:18:52.80 |
-37:26:10.5 |
HIP 99949 |
26.14 |
| 2026-02-04 00:00 |
20:18:56.64 |
-37:26:01.6 |
HIP 99949 |
26.91 |
| 2026-02-04 12:00 |
20:19:00.47 |
-37:25:52.8 |
HIP 99949 |
27.68 |
| 2026-02-05 00:00 |
20:19:04.29 |
-37:25:44.1 |
HIP 100335 |
27.65 |
| 2026-02-05 12:00 |
20:19:08.11 |
-37:25:35.6 |
HIP 100335 |
27.15 |
| 2026-02-06 00:00 |
20:19:11.92 |
-37:25:27.2 |
HIP 100335 |
26.66 |
| 2026-02-06 12:00 |
20:19:15.72 |
-37:25:19.0 |
HIP 100335 |
26.19 |
| 2026-02-07 00:00 |
20:19:19.51 |
-37:25:10.8 |
HIP 100335 |
25.73 |
| 2026-02-07 12:00 |
20:19:23.29 |
-37:25:02.9 |
HIP 100335 |
25.28 |
| 2026-02-08 00:00 |
20:19:27.06 |
-37:24:55.0 |
HIP 100335 |
24.85 |
| 2026-02-08 12:00 |
20:19:30.82 |
-37:24:47.3 |
HIP 100335 |
24.44 |
| 2026-02-09 00:00 |
20:19:34.58 |
-37:24:39.8 |
HIP 100335 |
24.04 |
| 2026-02-09 12:00 |
20:19:38.32 |
-37:24:32.3 |
HIP 100335 |
23.66 |
| 2026-02-10 00:00 |
20:19:42.05 |
-37:24:25.1 |
HIP 100335 |
23.29 |
| 2026-02-10 12:00 |
20:19:45.77 |
-37:24:17.9 |
HIP 100335 |
22.95 |
| 2026-02-11 00:00 |
20:19:49.49 |
-37:24:10.9 |
HIP 100335 |
22.62 |
| 2026-02-11 12:00 |
20:19:53.19 |
-37:24:04.1 |
HIP 100335 |
22.31 |
| 2026-02-12 00:00 |
20:19:56.88 |
-37:23:57.3 |
HIP 100335 |
22.02 |
| 2026-02-12 12:00 |
20:20:00.56 |
-37:23:50.8 |
HIP 100335 |
21.75 |
| 2026-02-13 00:00 |
20:20:04.22 |
-37:23:44.3 |
HIP 100335 |
21.51 |
| 2026-02-13 12:00 |
20:20:07.88 |
-37:23:38.0 |
HIP 100335 |
21.28 |
| 2026-02-14 00:00 |
20:20:11.52 |
-37:23:31.9 |
HIP 100335 |
21.08 |
| 2026-02-14 12:00 |
20:20:15.15 |
-37:23:25.9 |
HIP 100335 |
20.89 |
| 2026-02-15 00:00 |
20:20:18.77 |
-37:23:20.0 |
HIP 100335 |
20.73 |
| 2026-02-15 12:00 |
20:20:22.37 |
-37:23:14.3 |
HIP 100335 |
20.60 |
| 2026-02-16 00:00 |
20:20:25.96 |
-37:23:08.7 |
HIP 100335 |
20.48 |
| 2026-02-16 12:00 |
20:20:29.54 |
-37:23:03.3 |
HIP 100335 |
20.39 |
| 2026-02-17 00:00 |
20:20:33.11 |
-37:22:58.0 |
HIP 100335 |
20.32 |
| 2026-02-17 12:00 |
20:20:36.66 |
-37:22:52.9 |
HIP 100335 |
20.28 |
| 2026-02-18 00:00 |
20:20:40.19 |
-37:22:47.9 |
HIP 100335 |
20.25 |
| 2026-02-18 12:00 |
20:20:43.71 |
-37:22:43.1 |
HIP 100335 |
20.25 |
| 2026-02-19 00:00 |
20:20:47.22 |
-37:22:38.4 |
HIP 100335 |
20.27 |
| 2026-02-19 12:00 |
20:20:50.71 |
-37:22:33.8 |
HIP 100335 |
20.32 |
| 2026-02-20 00:00 |
20:20:54.18 |
-37:22:29.4 |
HIP 100335 |
20.38 |
| 2026-02-20 12:00 |
20:20:57.64 |
-37:22:25.2 |
HIP 100335 |
20.47 |
| 2026-02-21 00:00 |
20:21:01.09 |
-37:22:21.1 |
HIP 100335 |
20.57 |
| 2026-02-21 12:00 |
20:21:04.51 |
-37:22:17.1 |
HIP 100335 |
20.70 |
| 2026-02-22 00:00 |
20:21:07.92 |
-37:22:13.3 |
HIP 100502 |
20.64 |
| 2026-02-22 12:00 |
20:21:11.32 |
-37:22:09.7 |
HIP 100502 |
19.98 |
| 2026-02-23 00:00 |
20:21:14.70 |
-37:22:06.2 |
HIP 100502 |
19.33 |
| 2026-02-23 12:00 |
20:21:18.06 |
-37:22:02.8 |
HIP 100502 |
18.68 |
| 2026-02-24 00:00 |
20:21:21.40 |
-37:21:59.6 |
HIP 100502 |
18.04 |