| 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) |
| 2026-07-29 00:00 |
12:28:55.82 |
-18:25:02.7 |
HIP 60866 |
9.25 |
| 2026-07-29 12:00 |
12:28:58.20 |
-18:25:01.4 |
HIP 60866 |
9.60 |
| 2026-07-30 00:00 |
12:29:00.62 |
-18:25:00.3 |
HIP 60866 |
9.98 |
| 2026-07-30 12:00 |
12:29:03.07 |
-18:24:59.6 |
HIP 60866 |
10.38 |
| 2026-07-31 00:00 |
12:29:05.55 |
-18:24:59.1 |
HIP 60866 |
10.81 |
| 2026-07-31 12:00 |
12:29:08.06 |
-18:24:58.9 |
HIP 60866 |
11.26 |
| 2026-08-01 00:00 |
12:29:10.61 |
-18:24:58.9 |
HIP 60866 |
11.73 |
| 2026-08-01 12:00 |
12:29:13.18 |
-18:24:59.3 |
HIP 60866 |
12.22 |
| 2026-08-02 00:00 |
12:29:15.79 |
-18:24:59.9 |
HIP 60866 |
12.73 |
| 2026-08-02 12:00 |
12:29:18.43 |
-18:25:00.7 |
HIP 60866 |
13.26 |
| 2026-08-03 00:00 |
12:29:21.10 |
-18:25:01.9 |
HIP 60866 |
13.81 |
| 2026-08-03 12:00 |
12:29:23.81 |
-18:25:03.3 |
HIP 60866 |
14.37 |
| 2026-08-04 00:00 |
12:29:26.54 |
-18:25:05.0 |
HIP 60866 |
14.95 |
| 2026-08-04 12:00 |
12:29:29.31 |
-18:25:07.0 |
HIP 60866 |
15.54 |
| 2026-08-05 00:00 |
12:29:32.10 |
-18:25:09.2 |
HIP 60866 |
16.15 |
| 2026-08-05 12:00 |
12:29:34.93 |
-18:25:11.7 |
HIP 60866 |
16.77 |
| 2026-08-06 00:00 |
12:29:37.79 |
-18:25:14.5 |
HIP 60866 |
17.40 |
| 2026-08-06 12:00 |
12:29:40.67 |
-18:25:17.6 |
HIP 60866 |
18.04 |
| 2026-08-07 00:00 |
12:29:43.59 |
-18:25:20.9 |
HIP 60866 |
18.69 |
| 2026-08-07 12:00 |
12:29:46.54 |
-18:25:24.5 |
HIP 60866 |
19.36 |
| 2026-08-08 00:00 |
12:29:49.51 |
-18:25:28.4 |
HIP 60866 |
20.04 |
| 2026-08-08 12:00 |
12:29:52.52 |
-18:25:32.6 |
HIP 60866 |
20.72 |
| 2026-08-09 00:00 |
12:29:55.56 |
-18:25:37.0 |
HIP 60866 |
21.42 |
| 2026-08-09 12:00 |
12:29:58.62 |
-18:25:41.7 |
HIP 60866 |
22.13 |
| 2026-08-10 00:00 |
12:30:01.72 |
-18:25:46.7 |
HIP 60866 |
22.84 |
| 2026-08-10 12:00 |
12:30:04.84 |
-18:25:51.9 |
HIP 60866 |
23.57 |
| 2026-08-11 00:00 |
12:30:07.99 |
-18:25:57.4 |
HIP 60866 |
24.30 |
| 2026-08-11 12:00 |
12:30:11.17 |
-18:26:03.2 |
HIP 60866 |
25.05 |
| 2026-08-12 00:00 |
12:30:14.38 |
-18:26:09.3 |
HIP 60866 |
25.80 |
| 2026-08-12 12:00 |
12:30:17.62 |
-18:26:15.6 |
HIP 60866 |
26.56 |
| 2026-08-13 00:00 |
12:30:20.88 |
-18:26:22.2 |
HIP 60866 |
27.33 |
| 2026-08-13 12:00 |
12:30:24.18 |
-18:26:29.1 |
HIP 60866 |
28.11 |
| 2026-08-14 00:00 |
12:30:27.50 |
-18:26:36.2 |
HIP 60866 |
28.89 |
| 2026-08-14 12:00 |
12:30:30.84 |
-18:26:43.6 |
HIP 60866 |
29.69 |
| 2026-08-15 00:00 |
12:30:34.22 |
-18:26:51.3 |
HIP 60866 |
30.49 |
| 2026-08-15 12:00 |
12:30:37.62 |
-18:26:59.2 |
HIP 61005 |
31.13 |
| 2026-08-16 00:00 |
12:30:41.04 |
-18:27:07.4 |
HIP 61005 |
31.44 |
| 2026-08-16 12:00 |
12:30:44.49 |
-18:27:15.9 |
HIP 61207 |
30.88 |
| 2026-08-17 00:00 |
12:30:47.97 |
-18:27:24.6 |
HIP 61207 |
30.12 |
| 2026-08-17 12:00 |
12:30:51.48 |
-18:27:33.6 |
HIP 61207 |
29.36 |
| 2026-08-18 00:00 |
12:30:55.01 |
-18:27:42.9 |
HIP 61207 |
28.59 |
| 2026-08-18 12:00 |
12:30:58.56 |
-18:27:52.4 |
HIP 61207 |
27.82 |
| 2026-08-19 00:00 |
12:31:02.14 |
-18:28:02.2 |
HIP 61207 |
27.05 |