| Parameter |
Value |
| Designation |
C/2024 J4 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2025-04-26T00:08:43.143360Z |
| Orbit solution date (soln_date, UTC) |
2026-07-16T19:12:19Z |
| Obs used |
872 |
| NEO |
- |
| M1 |
11.800 |
| K1 |
4.500 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2024-05-11T09:58:56.611200Z |
| Discovery magnitude (MPC) |
20.17 G |
| Discovery observatory (MPC) |
G96 · University of Arizona Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2025-06-20.0000000 |
| e |
0.99909491 |
| q (au) |
5.695126 |
| a (au) |
6292.321580 |
| i (deg) |
117.529935 |
| Ω (om, deg) |
19.305956 |
| ω (w, deg) |
127.858553 |
| M (ma, deg) |
0.000109 |
Magnitude
Scatter + Global Linear
$$
M_a = (3.371 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
3.371 |
| n |
6.000 |
| gf |
0.998 |
| gb |
-0.979 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
13:08:38.45 |
+01:23:43.6 |
HIP 64082 |
11.10 |
| 2026-07-29 12:00 |
13:08:36.99 |
+01:21:08.4 |
HIP 64082 |
10.22 |
| 2026-07-30 00:00 |
13:08:35.67 |
+01:18:32.9 |
HIP 64082 |
10.01 |
| 2026-07-30 12:00 |
13:08:34.48 |
+01:15:57.2 |
HIP 64082 |
10.50 |
| 2026-07-31 00:00 |
13:08:33.41 |
+01:13:21.3 |
HIP 64082 |
11.59 |
| 2026-07-31 12:00 |
13:08:32.47 |
+01:10:45.1 |
HIP 64082 |
13.15 |
| 2026-08-01 00:00 |
13:08:31.66 |
+01:08:08.8 |
HIP 64082 |
15.03 |
| 2026-08-01 12:00 |
13:08:30.97 |
+01:05:32.2 |
HIP 64082 |
17.12 |
| 2026-08-02 00:00 |
13:08:30.41 |
+01:02:55.5 |
HIP 64082 |
19.35 |
| 2026-08-02 12:00 |
13:08:29.97 |
+01:00:18.5 |
HIP 64082 |
21.69 |
| 2026-08-03 00:00 |
13:08:29.66 |
+00:57:41.4 |
HIP 64207 |
20.39 |
| 2026-08-03 12:00 |
13:08:29.46 |
+00:55:04.0 |
HIP 64207 |
18.85 |
| 2026-08-04 00:00 |
13:08:29.39 |
+00:52:26.5 |
HIP 64207 |
17.54 |
| 2026-08-04 12:00 |
13:08:29.44 |
+00:49:48.7 |
HIP 64207 |
16.52 |
| 2026-08-05 00:00 |
13:08:29.61 |
+00:47:10.8 |
HIP 64207 |
15.85 |
| 2026-08-05 12:00 |
13:08:29.90 |
+00:44:32.7 |
HIP 64207 |
15.56 |
| 2026-08-06 00:00 |
13:08:30.31 |
+00:41:54.5 |
HIP 64207 |
15.69 |
| 2026-08-06 12:00 |
13:08:30.83 |
+00:39:16.0 |
HIP 64207 |
16.23 |
| 2026-08-07 00:00 |
13:08:31.47 |
+00:36:37.4 |
HIP 64207 |
17.13 |
| 2026-08-07 12:00 |
13:08:32.23 |
+00:33:58.6 |
HIP 64030 |
18.15 |
| 2026-08-08 00:00 |
13:08:33.10 |
+00:31:19.6 |
HIP 64030 |
18.72 |
| 2026-08-08 12:00 |
13:08:34.09 |
+00:28:40.5 |
HIP 64030 |
19.66 |
| 2026-08-09 00:00 |
13:08:35.18 |
+00:26:01.2 |
HIP 64030 |
20.93 |
| 2026-08-09 12:00 |
13:08:36.40 |
+00:23:21.7 |
HIP 64030 |
22.47 |
| 2026-08-10 00:00 |
13:08:37.72 |
+00:20:42.1 |
HIP 64030 |
24.24 |
| 2026-08-10 12:00 |
13:08:39.15 |
+00:18:02.3 |
HIP 64030 |
26.18 |
| 2026-08-11 00:00 |
13:08:40.69 |
+00:15:22.4 |
HIP 64030 |
28.27 |
| 2026-08-11 12:00 |
13:08:42.35 |
+00:12:42.4 |
HIP 64030 |
30.47 |
| 2026-08-12 00:00 |
13:08:44.11 |
+00:10:02.2 |
HIP 64030 |
32.76 |
| 2026-08-12 12:00 |
13:08:45.97 |
+00:07:21.8 |
HIP 64001 |
33.75 |
| 2026-08-13 00:00 |
13:08:47.94 |
+00:04:41.4 |
HIP 64001 |
32.78 |
| 2026-08-13 12:00 |
13:08:50.02 |
+00:02:00.8 |
HIP 64001 |
32.02 |
| 2026-08-14 00:00 |
13:08:52.20 |
-00:00:39.9 |
HIP 64001 |
31.51 |
| 2026-08-14 12:00 |
13:08:54.49 |
-00:03:20.8 |
HIP 64001 |
31.25 |
| 2026-08-15 00:00 |
13:08:56.88 |
-00:06:01.8 |
HIP 64001 |
31.26 |
| 2026-08-15 12:00 |
13:08:59.36 |
-00:08:42.8 |
HIP 64298 |
30.70 |
| 2026-08-16 00:00 |
13:09:01.95 |
-00:11:24.0 |
HIP 64298 |
28.78 |
| 2026-08-16 12:00 |
13:09:04.64 |
-00:14:05.3 |
HIP 64298 |
26.99 |
| 2026-08-17 00:00 |
13:09:07.43 |
-00:16:46.7 |
HIP 64247 |
24.70 |
| 2026-08-17 12:00 |
13:09:10.31 |
-00:19:28.2 |
HIP 64247 |
22.10 |
| 2026-08-18 00:00 |
13:09:13.29 |
-00:22:09.8 |
HIP 64247 |
19.54 |
| 2026-08-18 12:00 |
13:09:16.36 |
-00:24:51.5 |
HIP 64247 |
17.03 |
| 2026-08-19 00:00 |
13:09:19.53 |
-00:27:33.3 |
HIP 64247 |
14.61 |