| Parameter |
Value |
| Designation |
C/2009 G1 (STEREO) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2009-04-16T12:08:09.119040Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:30Z |
| Obs used |
119 |
| NEO |
- |
| M1 |
9.100 |
| K1 |
17.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2009-05-09.0000000 |
| e |
0.99767848 |
| q (au) |
1.128742 |
| a (au) |
486.208569 |
| i (deg) |
108.310256 |
| Ω (om, deg) |
120.634994 |
| ω (w, deg) |
175.444080 |
| M (ma, deg) |
0.002068 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.287 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.287 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.965 |
| 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 |
08:16:16.97 |
-03:47:24.7 |
HIP 40613 |
21.64 |
| 2026-06-01 12:00 |
08:16:18.90 |
-03:47:13.8 |
HIP 40613 |
21.34 |
| 2026-06-02 00:00 |
08:16:20.86 |
-03:47:03.0 |
HIP 40613 |
21.05 |
| 2026-06-02 12:00 |
08:16:22.83 |
-03:46:52.4 |
HIP 40613 |
20.75 |
| 2026-06-03 00:00 |
08:16:24.82 |
-03:46:42.0 |
HIP 40613 |
20.47 |
| 2026-06-03 12:00 |
08:16:26.83 |
-03:46:31.7 |
HIP 40613 |
20.18 |
| 2026-06-04 00:00 |
08:16:28.86 |
-03:46:21.6 |
HIP 40613 |
19.90 |
| 2026-06-04 12:00 |
08:16:30.91 |
-03:46:11.7 |
HIP 40613 |
19.63 |
| 2026-06-05 00:00 |
08:16:32.98 |
-03:46:01.9 |
HIP 40613 |
19.36 |
| 2026-06-05 12:00 |
08:16:35.06 |
-03:45:52.4 |
HIP 40613 |
19.09 |
| 2026-06-06 00:00 |
08:16:37.17 |
-03:45:43.0 |
HIP 40613 |
18.84 |
| 2026-06-06 12:00 |
08:16:39.29 |
-03:45:33.8 |
HIP 40613 |
18.59 |
| 2026-06-07 00:00 |
08:16:41.43 |
-03:45:24.7 |
HIP 40613 |
18.35 |
| 2026-06-07 12:00 |
08:16:43.59 |
-03:45:15.8 |
HIP 40613 |
18.11 |
| 2026-06-08 00:00 |
08:16:45.77 |
-03:45:07.1 |
HIP 40613 |
17.89 |
| 2026-06-08 12:00 |
08:16:47.96 |
-03:44:58.6 |
HIP 40613 |
17.68 |
| 2026-06-09 00:00 |
08:16:50.18 |
-03:44:50.3 |
HIP 40613 |
17.48 |
| 2026-06-09 12:00 |
08:16:52.41 |
-03:44:42.1 |
HIP 40613 |
17.29 |
| 2026-06-10 00:00 |
08:16:54.65 |
-03:44:34.1 |
HIP 40613 |
17.11 |
| 2026-06-10 12:00 |
08:16:56.92 |
-03:44:26.3 |
HIP 40613 |
16.94 |
| 2026-06-11 00:00 |
08:16:59.20 |
-03:44:18.7 |
HIP 40613 |
16.79 |
| 2026-06-11 12:00 |
08:17:01.50 |
-03:44:11.2 |
HIP 40613 |
16.65 |
| 2026-06-12 00:00 |
08:17:03.82 |
-03:44:03.9 |
HIP 40613 |
16.53 |
| 2026-06-12 12:00 |
08:17:06.15 |
-03:43:56.8 |
HIP 40613 |
16.43 |
| 2026-06-13 00:00 |
08:17:08.50 |
-03:43:49.9 |
HIP 40613 |
16.34 |
| 2026-06-13 12:00 |
08:17:10.86 |
-03:43:43.2 |
HIP 40613 |
16.27 |
| 2026-06-14 00:00 |
08:17:13.24 |
-03:43:36.6 |
HIP 40613 |
16.21 |
| 2026-06-14 12:00 |
08:17:15.64 |
-03:43:30.2 |
HIP 40613 |
16.18 |
| 2026-06-15 00:00 |
08:17:18.05 |
-03:43:24.0 |
HIP 40613 |
16.16 |
| 2026-06-15 12:00 |
08:17:20.48 |
-03:43:18.0 |
HIP 40613 |
16.17 |
| 2026-06-16 00:00 |
08:17:22.92 |
-03:43:12.2 |
HIP 40613 |
16.19 |
| 2026-06-16 12:00 |
08:17:25.38 |
-03:43:06.5 |
HIP 40613 |
16.24 |
| 2026-06-17 00:00 |
08:17:27.85 |
-03:43:01.0 |
HIP 40613 |
16.30 |
| 2026-06-17 12:00 |
08:17:30.34 |
-03:42:55.8 |
HIP 40613 |
16.39 |
| 2026-06-18 00:00 |
08:17:32.84 |
-03:42:50.6 |
HIP 40613 |
16.49 |
| 2026-06-18 12:00 |
08:17:35.36 |
-03:42:45.7 |
HIP 40613 |
16.62 |
| 2026-06-19 00:00 |
08:17:37.89 |
-03:42:41.0 |
HIP 40613 |
16.76 |
| 2026-06-19 12:00 |
08:17:40.44 |
-03:42:36.4 |
HIP 40613 |
16.93 |
| 2026-06-20 00:00 |
08:17:42.99 |
-03:42:32.0 |
HIP 40613 |
17.12 |
| 2026-06-20 12:00 |
08:17:45.57 |
-03:42:27.8 |
HIP 40613 |
17.32 |
| 2026-06-21 00:00 |
08:17:48.15 |
-03:42:23.8 |
HIP 40613 |
17.55 |
| 2026-06-21 12:00 |
08:17:50.75 |
-03:42:19.9 |
HIP 40613 |
17.79 |
| 2026-06-22 00:00 |
08:17:53.36 |
-03:42:16.3 |
HIP 40613 |
18.06 |