| 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) |
| 2026-03-26 00:00 |
16:02:13.17 |
-15:40:31.1 |
HIP 78430 |
26.87 |
| 2026-03-26 12:00 |
16:02:11.97 |
-15:40:25.0 |
HIP 78430 |
26.58 |
| 2026-03-27 00:00 |
16:02:10.76 |
-15:40:18.9 |
HIP 78430 |
26.29 |
| 2026-03-27 12:00 |
16:02:09.53 |
-15:40:12.8 |
HIP 78430 |
25.99 |
| 2026-03-28 00:00 |
16:02:08.28 |
-15:40:06.7 |
HIP 78430 |
25.68 |
| 2026-03-28 12:00 |
16:02:07.01 |
-15:40:00.5 |
HIP 78430 |
25.38 |
| 2026-03-29 00:00 |
16:02:05.73 |
-15:39:54.2 |
HIP 78430 |
25.07 |
| 2026-03-29 12:00 |
16:02:04.43 |
-15:39:48.0 |
HIP 78430 |
24.76 |
| 2026-03-30 00:00 |
16:02:03.12 |
-15:39:41.7 |
HIP 78430 |
24.44 |
| 2026-03-30 12:00 |
16:02:01.79 |
-15:39:35.3 |
HIP 78430 |
24.13 |
| 2026-03-31 00:00 |
16:02:00.44 |
-15:39:29.0 |
HIP 78430 |
23.81 |
| 2026-03-31 12:00 |
16:01:59.08 |
-15:39:22.6 |
HIP 78430 |
23.48 |
| 2026-04-01 00:00 |
16:01:57.71 |
-15:39:16.2 |
HIP 78430 |
23.16 |
| 2026-04-01 12:00 |
16:01:56.31 |
-15:39:09.7 |
HIP 78430 |
22.83 |
| 2026-04-02 00:00 |
16:01:54.90 |
-15:39:03.2 |
HIP 78430 |
22.50 |
| 2026-04-02 12:00 |
16:01:53.48 |
-15:38:56.7 |
HIP 78430 |
22.16 |
| 2026-04-03 00:00 |
16:01:52.04 |
-15:38:50.2 |
HIP 78430 |
21.83 |
| 2026-04-03 12:00 |
16:01:50.58 |
-15:38:43.6 |
HIP 78430 |
21.49 |
| 2026-04-04 00:00 |
16:01:49.11 |
-15:38:37.0 |
HIP 78430 |
21.15 |
| 2026-04-04 12:00 |
16:01:47.63 |
-15:38:30.4 |
HIP 78430 |
20.81 |
| 2026-04-05 00:00 |
16:01:46.13 |
-15:38:23.8 |
HIP 78430 |
20.47 |
| 2026-04-05 12:00 |
16:01:44.61 |
-15:38:17.1 |
HIP 78430 |
20.12 |
| 2026-04-06 00:00 |
16:01:43.08 |
-15:38:10.4 |
HIP 78430 |
19.77 |
| 2026-04-06 12:00 |
16:01:41.54 |
-15:38:03.6 |
HIP 78430 |
19.42 |
| 2026-04-07 00:00 |
16:01:39.98 |
-15:37:56.9 |
HIP 78430 |
19.07 |
| 2026-04-07 12:00 |
16:01:38.40 |
-15:37:50.1 |
HIP 78430 |
18.72 |
| 2026-04-08 00:00 |
16:01:36.82 |
-15:37:43.3 |
HIP 78430 |
18.37 |
| 2026-04-08 12:00 |
16:01:35.21 |
-15:37:36.5 |
HIP 78430 |
18.02 |
| 2026-04-09 00:00 |
16:01:33.60 |
-15:37:29.6 |
HIP 78430 |
17.67 |
| 2026-04-09 12:00 |
16:01:31.97 |
-15:37:22.7 |
HIP 78430 |
17.31 |
| 2026-04-10 00:00 |
16:01:30.32 |
-15:37:15.8 |
HIP 78430 |
16.96 |
| 2026-04-10 12:00 |
16:01:28.66 |
-15:37:08.9 |
HIP 78430 |
16.61 |
| 2026-04-11 00:00 |
16:01:26.99 |
-15:37:01.9 |
HIP 78430 |
16.25 |
| 2026-04-11 12:00 |
16:01:25.31 |
-15:36:55.0 |
HIP 78430 |
15.90 |
| 2026-04-12 00:00 |
16:01:23.61 |
-15:36:48.0 |
HIP 78430 |
15.55 |
| 2026-04-12 12:00 |
16:01:21.90 |
-15:36:41.0 |
HIP 78430 |
15.20 |
| 2026-04-13 00:00 |
16:01:20.17 |
-15:36:34.0 |
HIP 78430 |
14.86 |
| 2026-04-13 12:00 |
16:01:18.44 |
-15:36:26.9 |
HIP 78430 |
14.51 |
| 2026-04-14 00:00 |
16:01:16.69 |
-15:36:19.8 |
HIP 78430 |
14.17 |
| 2026-04-14 12:00 |
16:01:14.92 |
-15:36:12.8 |
HIP 78430 |
13.83 |
| 2026-04-15 00:00 |
16:01:13.15 |
-15:36:05.7 |
HIP 78430 |
13.50 |
| 2026-04-15 12:00 |
16:01:11.36 |
-15:35:58.5 |
HIP 78430 |
13.17 |
| 2026-04-16 00:00 |
16:01:09.56 |
-15:35:51.4 |
HIP 78430 |
12.85 |