| Parameter |
Value |
| Designation |
C/2023 H5 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2025-06-30T05:00:47.370240Z |
| Orbit solution date (soln_date, UTC) |
2026-03-31T09:42:18Z |
| Obs used |
2604 |
| NEO |
- |
| M1 |
8.600 |
| K1 |
7.750 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2023-04-19T04:23:52.540800Z |
| Discovery magnitude (MPC) |
20.29 G |
| Discovery observatory (MPC) |
G96 · Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2025-01-08.0000000 |
| e |
1.00038696 |
| q (au) |
4.312697 |
| a (au) |
-11145.113213 |
| i (deg) |
97.857006 |
| Ω (om, deg) |
159.479849 |
| ω (w, deg) |
60.088451 |
| M (ma, deg) |
-0.000145 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.673 + 4.075\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.673 |
| n |
4.075 |
| gf |
1.000 |
| gb |
-0.746 |
| k |
0.800 |
| δ90 |
9.998 |
| 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) |
| 2026-03-26 00:00 |
21:28:57.04 |
+61:52:31.0 |
HIP 106194 |
11.67 |
| 2026-03-26 12:00 |
21:29:39.01 |
+61:53:40.8 |
HIP 106194 |
6.74 |
| 2026-03-27 00:00 |
21:30:20.70 |
+61:54:51.6 |
HIP 106194 |
2.55 |
| 2026-03-27 12:00 |
21:31:02.10 |
+61:56:03.3 |
HIP 106194 |
4.30 |
| 2026-03-28 00:00 |
21:31:43.22 |
+61:57:16.0 |
HIP 106194 |
8.97 |
| 2026-03-28 12:00 |
21:32:24.05 |
+61:58:29.7 |
HIP 106400 |
4.59 |
| 2026-03-29 00:00 |
21:33:04.60 |
+61:59:44.3 |
HIP 106400 |
0.60 |
| 2026-03-29 12:00 |
21:33:44.87 |
+62:00:59.8 |
HIP 106400 |
5.27 |
| 2026-03-30 00:00 |
21:34:24.86 |
+62:02:16.3 |
HIP 106400 |
10.11 |
| 2026-03-30 12:00 |
21:35:04.56 |
+62:03:33.8 |
HIP 106400 |
14.94 |
| 2026-03-31 00:00 |
21:35:43.97 |
+62:04:52.1 |
HIP 106801 |
15.36 |
| 2026-03-31 12:00 |
21:36:23.11 |
+62:06:11.4 |
HIP 106801 |
10.85 |
| 2026-04-01 00:00 |
21:37:01.96 |
+62:07:31.7 |
HIP 106801 |
6.76 |
| 2026-04-01 12:00 |
21:37:40.52 |
+62:08:52.8 |
HIP 106801 |
4.32 |
| 2026-04-02 00:00 |
21:38:18.80 |
+62:10:14.9 |
HIP 106801 |
6.00 |
| 2026-04-02 12:00 |
21:38:56.80 |
+62:11:37.8 |
HIP 106801 |
9.84 |
| 2026-04-03 00:00 |
21:39:34.51 |
+62:13:01.7 |
HIP 106801 |
14.15 |
| 2026-04-03 12:00 |
21:40:11.93 |
+62:14:26.5 |
HIP 106801 |
18.59 |
| 2026-04-04 00:00 |
21:40:49.07 |
+62:15:52.2 |
HIP 107234 |
21.19 |
| 2026-04-04 12:00 |
21:41:25.92 |
+62:17:18.8 |
HIP 107234 |
19.30 |
| 2026-04-05 00:00 |
21:42:02.48 |
+62:18:46.2 |
HIP 107234 |
18.39 |
| 2026-04-05 12:00 |
21:42:38.76 |
+62:20:14.6 |
HIP 107374 |
17.25 |
| 2026-04-06 00:00 |
21:43:14.75 |
+62:21:43.8 |
HIP 107374 |
12.85 |
| 2026-04-06 12:00 |
21:43:50.45 |
+62:23:13.9 |
HIP 107374 |
8.50 |
| 2026-04-07 00:00 |
21:44:25.86 |
+62:24:44.9 |
HIP 107374 |
4.29 |
| 2026-04-07 12:00 |
21:45:00.98 |
+62:26:16.7 |
HIP 107374 |
1.62 |
| 2026-04-08 00:00 |
21:45:35.81 |
+62:27:49.4 |
HIP 107374 |
4.92 |
| 2026-04-08 12:00 |
21:46:10.35 |
+62:29:22.9 |
HIP 107374 |
9.07 |
| 2026-04-09 00:00 |
21:46:44.60 |
+62:30:57.3 |
HIP 107651 |
10.77 |
| 2026-04-09 12:00 |
21:47:18.56 |
+62:32:32.6 |
HIP 107651 |
6.74 |
| 2026-04-10 00:00 |
21:47:52.22 |
+62:34:08.6 |
HIP 107651 |
3.31 |
| 2026-04-10 12:00 |
21:48:25.59 |
+62:35:45.5 |
HIP 107651 |
3.42 |
| 2026-04-11 00:00 |
21:48:58.66 |
+62:37:23.3 |
HIP 107651 |
6.85 |
| 2026-04-11 12:00 |
21:49:31.44 |
+62:39:01.8 |
HIP 107651 |
10.77 |
| 2026-04-12 00:00 |
21:50:03.92 |
+62:40:41.1 |
HIP 107651 |
14.77 |
| 2026-04-12 12:00 |
21:50:36.10 |
+62:42:21.3 |
HIP 107984 |
13.65 |
| 2026-04-13 00:00 |
21:51:07.99 |
+62:44:02.2 |
HIP 107984 |
10.07 |
| 2026-04-13 12:00 |
21:51:39.57 |
+62:45:43.9 |
HIP 107984 |
7.04 |
| 2026-04-14 00:00 |
21:52:10.86 |
+62:47:26.4 |
HIP 107984 |
5.47 |
| 2026-04-14 12:00 |
21:52:41.84 |
+62:49:09.7 |
HIP 107984 |
6.48 |
| 2026-04-15 00:00 |
21:53:12.52 |
+62:50:53.7 |
HIP 107984 |
9.22 |
| 2026-04-15 12:00 |
21:53:42.90 |
+62:52:38.5 |
HIP 107984 |
12.58 |
| 2026-04-16 00:00 |
21:54:12.97 |
+62:54:24.1 |
HIP 108283 |
14.03 |