| Parameter |
Value |
| Designation |
C/1981 H1 (Bus) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1981-07-30T18:36:24.347520Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:29Z |
| Obs used |
26 |
| NEO |
- |
| M1 |
10.700 |
| K1 |
10.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1981-06-01.0000000 |
| e |
0.99886154 |
| q (au) |
2.458094 |
| a (au) |
2159.137236 |
| i (deg) |
160.663680 |
| Ω (om, deg) |
24.264517 |
| ω (w, deg) |
189.851632 |
| M (ma, deg) |
359.999413 |
Magnitude
Scatter + Global Linear
$$
M_a = (17.833 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
17.833 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.864 |
| k |
0.800 |
| 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) |
| 2026-05-12 00:00 |
02:18:56.05 |
+09:48:48.3 |
HIP 10764 |
6.41 |
| 2026-05-12 12:00 |
02:18:57.58 |
+09:48:56.0 |
HIP 10764 |
6.73 |
| 2026-05-13 00:00 |
02:18:59.10 |
+09:49:03.6 |
HIP 10764 |
7.05 |
| 2026-05-13 12:00 |
02:19:00.61 |
+09:49:11.1 |
HIP 10764 |
7.38 |
| 2026-05-14 00:00 |
02:19:02.13 |
+09:49:18.7 |
HIP 10764 |
7.72 |
| 2026-05-14 12:00 |
02:19:03.63 |
+09:49:26.2 |
HIP 10764 |
8.06 |
| 2026-05-15 00:00 |
02:19:05.14 |
+09:49:33.6 |
HIP 10764 |
8.40 |
| 2026-05-15 12:00 |
02:19:06.64 |
+09:49:41.1 |
HIP 10764 |
8.74 |
| 2026-05-16 00:00 |
02:19:08.14 |
+09:49:48.5 |
HIP 10764 |
9.09 |
| 2026-05-16 12:00 |
02:19:09.63 |
+09:49:55.8 |
HIP 10764 |
9.45 |
| 2026-05-17 00:00 |
02:19:11.12 |
+09:50:03.1 |
HIP 10764 |
9.80 |
| 2026-05-17 12:00 |
02:19:12.61 |
+09:50:10.4 |
HIP 10764 |
10.15 |
| 2026-05-18 00:00 |
02:19:14.09 |
+09:50:17.7 |
HIP 10764 |
10.51 |
| 2026-05-18 12:00 |
02:19:15.56 |
+09:50:24.9 |
HIP 10764 |
10.86 |
| 2026-05-19 00:00 |
02:19:17.03 |
+09:50:32.1 |
HIP 10764 |
11.22 |
| 2026-05-19 12:00 |
02:19:18.50 |
+09:50:39.2 |
HIP 10764 |
11.58 |
| 2026-05-20 00:00 |
02:19:19.96 |
+09:50:46.3 |
HIP 10764 |
11.94 |
| 2026-05-20 12:00 |
02:19:21.42 |
+09:50:53.3 |
HIP 10764 |
12.29 |
| 2026-05-21 00:00 |
02:19:22.87 |
+09:51:00.3 |
HIP 10764 |
12.65 |
| 2026-05-21 12:00 |
02:19:24.31 |
+09:51:07.3 |
HIP 10764 |
13.01 |
| 2026-05-22 00:00 |
02:19:25.75 |
+09:51:14.2 |
HIP 10764 |
13.36 |
| 2026-05-22 12:00 |
02:19:27.19 |
+09:51:21.1 |
HIP 10764 |
13.72 |
| 2026-05-23 00:00 |
02:19:28.62 |
+09:51:27.9 |
HIP 10764 |
14.08 |
| 2026-05-23 12:00 |
02:19:30.04 |
+09:51:34.7 |
HIP 10764 |
14.43 |
| 2026-05-24 00:00 |
02:19:31.46 |
+09:51:41.5 |
HIP 10764 |
14.79 |
| 2026-05-24 12:00 |
02:19:32.87 |
+09:51:48.2 |
HIP 10764 |
15.14 |
| 2026-05-25 00:00 |
02:19:34.28 |
+09:51:54.9 |
HIP 10764 |
15.49 |
| 2026-05-25 12:00 |
02:19:35.68 |
+09:52:01.5 |
HIP 10764 |
15.84 |
| 2026-05-26 00:00 |
02:19:37.07 |
+09:52:08.1 |
HIP 10764 |
16.19 |
| 2026-05-26 12:00 |
02:19:38.46 |
+09:52:14.6 |
HIP 10764 |
16.54 |
| 2026-05-27 00:00 |
02:19:39.84 |
+09:52:21.1 |
HIP 10764 |
16.89 |
| 2026-05-27 12:00 |
02:19:41.22 |
+09:52:27.5 |
HIP 10764 |
17.24 |
| 2026-05-28 00:00 |
02:19:42.59 |
+09:52:33.9 |
HIP 10764 |
17.58 |
| 2026-05-28 12:00 |
02:19:43.95 |
+09:52:40.2 |
HIP 10764 |
17.93 |
| 2026-05-29 00:00 |
02:19:45.31 |
+09:52:46.5 |
HIP 10764 |
18.27 |
| 2026-05-29 12:00 |
02:19:46.66 |
+09:52:52.8 |
HIP 10937 |
17.93 |
| 2026-05-30 00:00 |
02:19:48.00 |
+09:52:59.0 |
HIP 10937 |
17.59 |
| 2026-05-30 12:00 |
02:19:49.33 |
+09:53:05.1 |
HIP 10937 |
17.25 |
| 2026-05-31 00:00 |
02:19:50.66 |
+09:53:11.2 |
HIP 10937 |
16.91 |
| 2026-05-31 12:00 |
02:19:51.98 |
+09:53:17.3 |
HIP 10937 |
16.57 |
| 2026-06-01 00:00 |
02:19:53.30 |
+09:53:23.3 |
HIP 10937 |
16.24 |
| 2026-06-01 12:00 |
02:19:54.60 |
+09:53:29.3 |
HIP 10937 |
15.90 |
| 2026-06-02 00:00 |
02:19:55.90 |
+09:53:35.2 |
HIP 10937 |
15.57 |