| Parameter |
Value |
| Designation |
C/1991 L3 (Levy) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1991-07-08T04:44:18.885120Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:41Z |
| Obs used |
136 |
| NEO |
Yes |
| M1 |
8.900 |
| K1 |
14.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1991-12-29.0000000 |
| e |
0.92885840 |
| q (au) |
0.982684 |
| a (au) |
13.813077 |
| i (deg) |
19.190108 |
| Ω (om, deg) |
329.431597 |
| ω (w, deg) |
41.478818 |
| M (ma, deg) |
3.336757 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.810 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.810 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.533 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 1991-07-08 |
1991-10-09 |
+1.2945 |
-0.124 |
| 1991-10-09 |
1993-01-21 |
-0.0631 |
+0.767 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
12:35:32.18 |
-18:46:51.0 |
HIP 61551 |
21.51 |
| 2026-09-20 12:00 |
12:35:36.85 |
-18:47:15.7 |
HIP 61551 |
20.39 |
| 2026-09-21 00:00 |
12:35:41.54 |
-18:47:40.6 |
HIP 61551 |
19.27 |
| 2026-09-21 12:00 |
12:35:46.23 |
-18:48:05.7 |
HIP 61551 |
18.16 |
| 2026-09-22 00:00 |
12:35:50.93 |
-18:48:31.0 |
HIP 61551 |
17.05 |
| 2026-09-22 12:00 |
12:35:55.64 |
-18:48:56.5 |
HIP 61551 |
15.95 |
| 2026-09-23 00:00 |
12:36:00.35 |
-18:49:22.2 |
HIP 61551 |
14.87 |
| 2026-09-23 12:00 |
12:36:05.08 |
-18:49:48.0 |
HIP 61551 |
13.79 |
| 2026-09-24 00:00 |
12:36:09.80 |
-18:50:14.1 |
HIP 61551 |
12.74 |
| 2026-09-24 12:00 |
12:36:14.54 |
-18:50:40.3 |
HIP 61551 |
11.71 |
| 2026-09-25 00:00 |
12:36:19.28 |
-18:51:06.6 |
HIP 61551 |
10.72 |
| 2026-09-25 12:00 |
12:36:24.02 |
-18:51:33.2 |
HIP 61551 |
9.76 |
| 2026-09-26 00:00 |
12:36:28.77 |
-18:52:00.0 |
HIP 61551 |
8.87 |
| 2026-09-26 12:00 |
12:36:33.52 |
-18:52:26.8 |
HIP 61551 |
8.06 |
| 2026-09-27 00:00 |
12:36:38.28 |
-18:52:53.9 |
HIP 61551 |
7.35 |
| 2026-09-27 12:00 |
12:36:43.05 |
-18:53:21.1 |
HIP 61551 |
6.79 |
| 2026-09-28 00:00 |
12:36:47.82 |
-18:53:48.6 |
HIP 61551 |
6.40 |
| 2026-09-28 12:00 |
12:36:52.59 |
-18:54:16.1 |
HIP 61551 |
6.23 |
| 2026-09-29 00:00 |
12:36:57.36 |
-18:54:43.9 |
HIP 61551 |
6.30 |
| 2026-09-29 12:00 |
12:37:02.14 |
-18:55:11.8 |
HIP 61551 |
6.59 |
| 2026-09-30 00:00 |
12:37:06.92 |
-18:55:39.9 |
HIP 61551 |
7.08 |
| 2026-09-30 12:00 |
12:37:11.71 |
-18:56:08.1 |
HIP 61551 |
7.74 |
| 2026-10-01 00:00 |
12:37:16.50 |
-18:56:36.5 |
HIP 61551 |
8.52 |
| 2026-10-01 12:00 |
12:37:21.29 |
-18:57:05.0 |
HIP 61551 |
9.40 |
| 2026-10-02 00:00 |
12:37:26.08 |
-18:57:33.8 |
HIP 61551 |
10.35 |
| 2026-10-02 12:00 |
12:37:30.87 |
-18:58:02.6 |
HIP 61551 |
11.35 |
| 2026-10-03 00:00 |
12:37:35.67 |
-18:58:31.6 |
HIP 61551 |
12.39 |
| 2026-10-03 12:00 |
12:37:40.46 |
-18:59:00.8 |
HIP 61551 |
13.47 |
| 2026-10-04 00:00 |
12:37:45.26 |
-18:59:30.1 |
HIP 61551 |
14.57 |
| 2026-10-04 12:00 |
12:37:50.06 |
-18:59:59.6 |
HIP 61551 |
15.69 |
| 2026-10-05 00:00 |
12:37:54.86 |
-19:00:29.2 |
HIP 61551 |
16.82 |
| 2026-10-05 12:00 |
12:37:59.65 |
-19:00:59.0 |
HIP 61551 |
17.97 |
| 2026-10-06 00:00 |
12:38:04.45 |
-19:01:28.9 |
HIP 61551 |
19.14 |
| 2026-10-06 12:00 |
12:38:09.25 |
-19:01:59.0 |
HIP 61551 |
20.31 |
| 2026-10-07 00:00 |
12:38:14.05 |
-19:02:29.2 |
HIP 61761 |
21.22 |
| 2026-10-07 12:00 |
12:38:18.84 |
-19:02:59.5 |
HIP 61761 |
20.00 |
| 2026-10-08 00:00 |
12:38:23.63 |
-19:03:30.0 |
HIP 61761 |
18.78 |
| 2026-10-08 12:00 |
12:38:28.43 |
-19:04:00.6 |
HIP 61761 |
17.57 |
| 2026-10-09 00:00 |
12:38:33.22 |
-19:04:31.3 |
HIP 61761 |
16.35 |
| 2026-10-09 12:00 |
12:38:38.00 |
-19:05:02.2 |
HIP 61761 |
15.14 |
| 2026-10-10 00:00 |
12:38:42.79 |
-19:05:33.2 |
HIP 61761 |
13.94 |
| 2026-10-10 12:00 |
12:38:47.57 |
-19:06:04.3 |
HIP 61761 |
12.74 |
| 2026-10-11 00:00 |
12:38:52.34 |
-19:06:35.6 |
HIP 61761 |
11.54 |