| Parameter |
Value |
| Designation |
C/1999 H1 (Lee) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1999-07-11T04:07:54.053760Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:59Z |
| Obs used |
1019 |
| NEO |
- |
| M1 |
9.400 |
| K1 |
11.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1999-08-17.0000000 |
| e |
0.99974475 |
| q (au) |
0.708107 |
| a (au) |
2774.129592 |
| i (deg) |
149.352905 |
| Ω (om, deg) |
162.650897 |
| ω (w, deg) |
40.701567 |
| M (ma, deg) |
0.000248 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.906 + 4.943\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.906 |
| n |
4.943 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.998 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 1999-04-16 |
1999-05-14 |
+7.7311 |
-0.623 |
| 1999-05-14 |
1999-07-04 |
-1.8550 |
+0.208 |
| 1999-07-27 |
2000-01-08 |
+0.8828 |
+0.043 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
21:49:14.41 |
-27:24:47.6 |
HIP 107766 |
8.78 |
| 2026-05-12 12:00 |
21:49:14.56 |
-27:24:56.0 |
HIP 107766 |
8.75 |
| 2026-05-13 00:00 |
21:49:14.69 |
-27:25:04.6 |
HIP 107766 |
8.74 |
| 2026-05-13 12:00 |
21:49:14.79 |
-27:25:13.3 |
HIP 107766 |
8.73 |
| 2026-05-14 00:00 |
21:49:14.88 |
-27:25:22.0 |
HIP 107766 |
8.73 |
| 2026-05-14 12:00 |
21:49:14.94 |
-27:25:30.9 |
HIP 107766 |
8.74 |
| 2026-05-15 00:00 |
21:49:14.98 |
-27:25:39.9 |
HIP 107766 |
8.75 |
| 2026-05-15 12:00 |
21:49:15.00 |
-27:25:48.9 |
HIP 107766 |
8.77 |
| 2026-05-16 00:00 |
21:49:15.00 |
-27:25:58.1 |
HIP 107766 |
8.80 |
| 2026-05-16 12:00 |
21:49:14.98 |
-27:26:07.4 |
HIP 107766 |
8.84 |
| 2026-05-17 00:00 |
21:49:14.94 |
-27:26:16.7 |
HIP 107766 |
8.88 |
| 2026-05-17 12:00 |
21:49:14.87 |
-27:26:26.2 |
HIP 107766 |
8.93 |
| 2026-05-18 00:00 |
21:49:14.79 |
-27:26:35.8 |
HIP 107766 |
8.99 |
| 2026-05-18 12:00 |
21:49:14.68 |
-27:26:45.5 |
HIP 107766 |
9.06 |
| 2026-05-19 00:00 |
21:49:14.55 |
-27:26:55.2 |
HIP 107766 |
9.13 |
| 2026-05-19 12:00 |
21:49:14.40 |
-27:27:05.1 |
HIP 107766 |
9.21 |
| 2026-05-20 00:00 |
21:49:14.22 |
-27:27:15.1 |
HIP 107766 |
9.30 |
| 2026-05-20 12:00 |
21:49:14.03 |
-27:27:25.1 |
HIP 107766 |
9.40 |
| 2026-05-21 00:00 |
21:49:13.81 |
-27:27:35.3 |
HIP 107766 |
9.50 |
| 2026-05-21 12:00 |
21:49:13.58 |
-27:27:45.5 |
HIP 107766 |
9.61 |
| 2026-05-22 00:00 |
21:49:13.32 |
-27:27:55.9 |
HIP 107766 |
9.73 |
| 2026-05-22 12:00 |
21:49:13.04 |
-27:28:06.3 |
HIP 107766 |
9.85 |
| 2026-05-23 00:00 |
21:49:12.74 |
-27:28:16.8 |
HIP 107766 |
9.98 |
| 2026-05-23 12:00 |
21:49:12.42 |
-27:28:27.4 |
HIP 107766 |
10.12 |
| 2026-05-24 00:00 |
21:49:12.07 |
-27:28:38.2 |
HIP 107766 |
10.27 |
| 2026-05-24 12:00 |
21:49:11.71 |
-27:28:49.0 |
HIP 107766 |
10.42 |
| 2026-05-25 00:00 |
21:49:11.32 |
-27:28:59.8 |
HIP 107766 |
10.58 |
| 2026-05-25 12:00 |
21:49:10.91 |
-27:29:10.8 |
HIP 107766 |
10.74 |
| 2026-05-26 00:00 |
21:49:10.49 |
-27:29:21.9 |
HIP 107766 |
10.91 |
| 2026-05-26 12:00 |
21:49:10.04 |
-27:29:33.0 |
HIP 107766 |
11.08 |
| 2026-05-27 00:00 |
21:49:09.57 |
-27:29:44.2 |
HIP 107766 |
11.27 |
| 2026-05-27 12:00 |
21:49:09.08 |
-27:29:55.6 |
HIP 107766 |
11.45 |
| 2026-05-28 00:00 |
21:49:08.56 |
-27:30:07.0 |
HIP 107766 |
11.65 |
| 2026-05-28 12:00 |
21:49:08.03 |
-27:30:18.4 |
HIP 107766 |
11.85 |
| 2026-05-29 00:00 |
21:49:07.48 |
-27:30:30.0 |
HIP 107766 |
12.05 |
| 2026-05-29 12:00 |
21:49:06.90 |
-27:30:41.7 |
HIP 107766 |
12.26 |
| 2026-05-30 00:00 |
21:49:06.30 |
-27:30:53.4 |
HIP 107766 |
12.48 |
| 2026-05-30 12:00 |
21:49:05.69 |
-27:31:05.2 |
HIP 107766 |
12.70 |
| 2026-05-31 00:00 |
21:49:05.05 |
-27:31:17.1 |
HIP 107766 |
12.92 |
| 2026-05-31 12:00 |
21:49:04.39 |
-27:31:29.0 |
HIP 107766 |
13.16 |
| 2026-06-01 00:00 |
21:49:03.71 |
-27:31:41.1 |
HIP 107766 |
13.39 |
| 2026-06-01 12:00 |
21:49:03.01 |
-27:31:53.2 |
HIP 107766 |
13.63 |
| 2026-06-02 00:00 |
21:49:02.29 |
-27:32:05.4 |
HIP 107766 |
13.88 |