| Parameter |
Value |
| Designation |
C/1998 H1 (Stonehouse) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1998-04-14T10:13:23.263680Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:53Z |
| Obs used |
407 |
| NEO |
- |
| M1 |
10.000 |
| K1 |
9.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1998-05-13.0000000 |
| e |
0.99794041 |
| q (au) |
1.487291 |
| a (au) |
722.129549 |
| i (deg) |
104.692960 |
| Ω (om, deg) |
222.109070 |
| ω (w, deg) |
1.325283 |
| M (ma, deg) |
0.001451 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.349 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.349 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.506 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
02:39:03.21 |
+33:44:52.1 |
HIP 12417 |
15.59 |
| 2026-07-29 12:00 |
02:39:03.48 |
+33:45:02.7 |
HIP 12417 |
15.42 |
| 2026-07-30 00:00 |
02:39:03.73 |
+33:45:13.2 |
HIP 12417 |
15.25 |
| 2026-07-30 12:00 |
02:39:03.96 |
+33:45:23.7 |
HIP 12417 |
15.09 |
| 2026-07-31 00:00 |
02:39:04.17 |
+33:45:34.1 |
HIP 12417 |
14.93 |
| 2026-07-31 12:00 |
02:39:04.35 |
+33:45:44.5 |
HIP 12417 |
14.77 |
| 2026-08-01 00:00 |
02:39:04.52 |
+33:45:54.7 |
HIP 12417 |
14.62 |
| 2026-08-01 12:00 |
02:39:04.66 |
+33:46:04.9 |
HIP 12417 |
14.47 |
| 2026-08-02 00:00 |
02:39:04.77 |
+33:46:15.0 |
HIP 12417 |
14.33 |
| 2026-08-02 12:00 |
02:39:04.87 |
+33:46:25.0 |
HIP 12417 |
14.19 |
| 2026-08-03 00:00 |
02:39:04.94 |
+33:46:35.0 |
HIP 12417 |
14.06 |
| 2026-08-03 12:00 |
02:39:04.99 |
+33:46:44.8 |
HIP 12417 |
13.93 |
| 2026-08-04 00:00 |
02:39:05.02 |
+33:46:54.6 |
HIP 12417 |
13.81 |
| 2026-08-04 12:00 |
02:39:05.03 |
+33:47:04.3 |
HIP 12417 |
13.69 |
| 2026-08-05 00:00 |
02:39:05.01 |
+33:47:14.0 |
HIP 12417 |
13.58 |
| 2026-08-05 12:00 |
02:39:04.97 |
+33:47:23.5 |
HIP 12417 |
13.47 |
| 2026-08-06 00:00 |
02:39:04.91 |
+33:47:33.0 |
HIP 12417 |
13.37 |
| 2026-08-06 12:00 |
02:39:04.83 |
+33:47:42.3 |
HIP 12417 |
13.27 |
| 2026-08-07 00:00 |
02:39:04.72 |
+33:47:51.6 |
HIP 12417 |
13.18 |
| 2026-08-07 12:00 |
02:39:04.59 |
+33:48:00.8 |
HIP 12417 |
13.09 |
| 2026-08-08 00:00 |
02:39:04.44 |
+33:48:09.9 |
HIP 12417 |
13.01 |
| 2026-08-08 12:00 |
02:39:04.26 |
+33:48:19.0 |
HIP 12417 |
12.94 |
| 2026-08-09 00:00 |
02:39:04.07 |
+33:48:27.9 |
HIP 12417 |
12.87 |
| 2026-08-09 12:00 |
02:39:03.85 |
+33:48:36.7 |
HIP 12417 |
12.81 |
| 2026-08-10 00:00 |
02:39:03.60 |
+33:48:45.5 |
HIP 12417 |
12.75 |
| 2026-08-10 12:00 |
02:39:03.34 |
+33:48:54.2 |
HIP 12417 |
12.70 |
| 2026-08-11 00:00 |
02:39:03.05 |
+33:49:02.7 |
HIP 12417 |
12.66 |
| 2026-08-11 12:00 |
02:39:02.74 |
+33:49:11.2 |
HIP 12417 |
12.62 |
| 2026-08-12 00:00 |
02:39:02.41 |
+33:49:19.6 |
HIP 12417 |
12.59 |
| 2026-08-12 12:00 |
02:39:02.05 |
+33:49:27.9 |
HIP 12417 |
12.57 |
| 2026-08-13 00:00 |
02:39:01.67 |
+33:49:36.1 |
HIP 12417 |
12.55 |
| 2026-08-13 12:00 |
02:39:01.27 |
+33:49:44.2 |
HIP 12417 |
12.54 |
| 2026-08-14 00:00 |
02:39:00.85 |
+33:49:52.2 |
HIP 12417 |
12.53 |
| 2026-08-14 12:00 |
02:39:00.40 |
+33:50:00.1 |
HIP 12417 |
12.54 |
| 2026-08-15 00:00 |
02:38:59.93 |
+33:50:07.9 |
HIP 12417 |
12.55 |
| 2026-08-15 12:00 |
02:38:59.44 |
+33:50:15.6 |
HIP 12417 |
12.56 |
| 2026-08-16 00:00 |
02:38:58.92 |
+33:50:23.2 |
HIP 12417 |
12.59 |
| 2026-08-16 12:00 |
02:38:58.38 |
+33:50:30.7 |
HIP 12417 |
12.62 |
| 2026-08-17 00:00 |
02:38:57.82 |
+33:50:38.1 |
HIP 12417 |
12.65 |
| 2026-08-17 12:00 |
02:38:57.24 |
+33:50:45.4 |
HIP 12417 |
12.70 |
| 2026-08-18 00:00 |
02:38:56.64 |
+33:50:52.6 |
HIP 12417 |
12.75 |
| 2026-08-18 12:00 |
02:38:56.01 |
+33:50:59.7 |
HIP 12417 |
12.81 |
| 2026-08-19 00:00 |
02:38:55.36 |
+33:51:06.7 |
HIP 12417 |
12.88 |