| Parameter |
Value |
| Designation |
C/1997 H2 (SOHO) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1997-05-03T04:04:48Z |
| Orbit solution date (soln_date, UTC) |
- |
| Obs used |
115 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1997-05-03.1700000 |
| e |
1.00000000 |
| q (au) |
0.136100 |
| a (au) |
- |
| i (deg) |
18.320000 |
| Ω (om, deg) |
225.820000 |
| ω (w, deg) |
201.470000 |
| M (ma, deg) |
- |
Magnitude
Scatter + Global Linear
$$
M_a = (H_0 + n\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
- |
| n |
- |
| gf |
- |
| gb |
- |
| k |
- |
| δ90 |
- |
| 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) |
| 2026-09-20 00:00 |
15:54:41.78 |
-15:23:07.7 |
HIP 77874 |
18.39 |
| 2026-09-20 12:00 |
15:54:42.82 |
-15:23:13.2 |
HIP 77874 |
18.41 |
| 2026-09-21 00:00 |
15:54:43.88 |
-15:23:18.8 |
HIP 77874 |
18.43 |
| 2026-09-21 12:00 |
15:54:44.95 |
-15:23:24.5 |
HIP 77874 |
18.46 |
| 2026-09-22 00:00 |
15:54:46.03 |
-15:23:30.2 |
HIP 77874 |
18.50 |
| 2026-09-22 12:00 |
15:54:47.14 |
-15:23:35.9 |
HIP 77874 |
18.54 |
| 2026-09-23 00:00 |
15:54:48.26 |
-15:23:41.6 |
HIP 77874 |
18.59 |
| 2026-09-23 12:00 |
15:54:49.39 |
-15:23:47.4 |
HIP 77874 |
18.64 |
| 2026-09-24 00:00 |
15:54:50.54 |
-15:23:53.2 |
HIP 77874 |
18.70 |
| 2026-09-24 12:00 |
15:54:51.71 |
-15:23:59.1 |
HIP 77874 |
18.77 |
| 2026-09-25 00:00 |
15:54:52.90 |
-15:24:05.0 |
HIP 77874 |
18.84 |
| 2026-09-25 12:00 |
15:54:54.10 |
-15:24:10.9 |
HIP 77874 |
18.91 |
| 2026-09-26 00:00 |
15:54:55.31 |
-15:24:16.9 |
HIP 77874 |
19.00 |
| 2026-09-26 12:00 |
15:54:56.54 |
-15:24:22.9 |
HIP 78010 |
19.05 |
| 2026-09-27 00:00 |
15:54:57.79 |
-15:24:28.9 |
HIP 78010 |
18.94 |
| 2026-09-27 12:00 |
15:54:59.05 |
-15:24:35.0 |
HIP 78010 |
18.84 |
| 2026-09-28 00:00 |
15:55:00.33 |
-15:24:41.1 |
HIP 78010 |
18.74 |
| 2026-09-28 12:00 |
15:55:01.62 |
-15:24:47.2 |
HIP 78010 |
18.64 |
| 2026-09-29 00:00 |
15:55:02.93 |
-15:24:53.4 |
HIP 78010 |
18.54 |
| 2026-09-29 12:00 |
15:55:04.26 |
-15:24:59.6 |
HIP 78010 |
18.45 |
| 2026-09-30 00:00 |
15:55:05.59 |
-15:25:05.8 |
HIP 78010 |
18.36 |
| 2026-09-30 12:00 |
15:55:06.95 |
-15:25:12.1 |
HIP 78010 |
18.28 |
| 2026-10-01 00:00 |
15:55:08.32 |
-15:25:18.3 |
HIP 78010 |
18.20 |
| 2026-10-01 12:00 |
15:55:09.70 |
-15:25:24.7 |
HIP 78010 |
18.13 |
| 2026-10-02 00:00 |
15:55:11.10 |
-15:25:31.0 |
HIP 78010 |
18.06 |
| 2026-10-02 12:00 |
15:55:12.51 |
-15:25:37.4 |
HIP 78010 |
18.00 |
| 2026-10-03 00:00 |
15:55:13.94 |
-15:25:43.8 |
HIP 78010 |
17.95 |
| 2026-10-03 12:00 |
15:55:15.38 |
-15:25:50.2 |
HIP 78010 |
17.90 |
| 2026-10-04 00:00 |
15:55:16.84 |
-15:25:56.7 |
HIP 78010 |
17.85 |
| 2026-10-04 12:00 |
15:55:18.31 |
-15:26:03.2 |
HIP 78010 |
17.81 |
| 2026-10-05 00:00 |
15:55:19.80 |
-15:26:09.7 |
HIP 78010 |
17.78 |
| 2026-10-05 12:00 |
15:55:21.30 |
-15:26:16.2 |
HIP 78010 |
17.76 |
| 2026-10-06 00:00 |
15:55:22.81 |
-15:26:22.8 |
HIP 78010 |
17.74 |
| 2026-10-06 12:00 |
15:55:24.34 |
-15:26:29.4 |
HIP 78010 |
17.74 |
| 2026-10-07 00:00 |
15:55:25.88 |
-15:26:36.0 |
HIP 78010 |
17.74 |
| 2026-10-07 12:00 |
15:55:27.44 |
-15:26:42.6 |
HIP 78010 |
17.74 |
| 2026-10-08 00:00 |
15:55:29.01 |
-15:26:49.3 |
HIP 78010 |
17.76 |
| 2026-10-08 12:00 |
15:55:30.59 |
-15:26:56.0 |
HIP 78010 |
17.78 |
| 2026-10-09 00:00 |
15:55:32.19 |
-15:27:02.7 |
HIP 78010 |
17.82 |
| 2026-10-09 12:00 |
15:55:33.80 |
-15:27:09.4 |
HIP 78010 |
17.86 |
| 2026-10-10 00:00 |
15:55:35.42 |
-15:27:16.2 |
HIP 78010 |
17.91 |
| 2026-10-10 12:00 |
15:55:37.06 |
-15:27:22.9 |
HIP 78010 |
17.97 |
| 2026-10-11 00:00 |
15:55:38.71 |
-15:27:29.7 |
HIP 78010 |
18.04 |