C/2023 H2 (Lemmon)
| Parameter |
Value |
| Designation |
C/2023 H2 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2023-10-29T04:33:37.779840Z |
| Orbit solution date (soln_date, UTC) |
2024-07-30T14:57:25Z |
| Obs used |
724 |
| NEO |
- |
| M1 |
16.100 |
| K1 |
5.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2023-04-23T06:42:47.548800Z |
| Discovery magnitude (MPC) |
20.78 G |
| Discovery observatory (MPC) |
G96 · Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2023-10-07.0000000 |
| e |
0.99628184 |
| q (au) |
0.894405 |
| a (au) |
240.550492 |
| i (deg) |
113.753483 |
| Ω (om, deg) |
217.044806 |
| ω (w, deg) |
150.650349 |
| M (ma, deg) |
359.994138 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.949 + 4.643\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.949 |
| n |
4.643 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
0.800 |
| δ90 |
1.000 |
| 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 |
| 2023-03-26 |
2023-10-28 |
+3.8410 |
-1.393 |
| 2023-10-29 |
2024-02-05 |
-12.2263 |
-1.021 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
17:36:09.54 |
-76:54:00.6 |
HIP 86129 |
1.47 |
| 2026-02-03 12:00 |
17:36:38.54 |
-76:55:48.5 |
HIP 86129 |
3.70 |
| 2026-02-04 00:00 |
17:37:07.29 |
-76:57:37.0 |
HIP 86129 |
6.09 |
| 2026-02-04 12:00 |
17:37:35.79 |
-76:59:26.2 |
HIP 86129 |
8.50 |
| 2026-02-05 00:00 |
17:38:04.03 |
-77:01:16.1 |
HIP 86129 |
10.91 |
| 2026-02-05 12:00 |
17:38:32.02 |
-77:03:06.6 |
HIP 86129 |
13.33 |
| 2026-02-06 00:00 |
17:38:59.74 |
-77:04:57.7 |
HIP 86129 |
15.75 |
| 2026-02-06 12:00 |
17:39:27.20 |
-77:06:49.5 |
HIP 86129 |
18.16 |
| 2026-02-07 00:00 |
17:39:54.39 |
-77:08:42.0 |
HIP 86129 |
20.57 |
| 2026-02-07 12:00 |
17:40:21.32 |
-77:10:35.0 |
HIP 86867 |
18.46 |
| 2026-02-08 00:00 |
17:40:47.96 |
-77:12:28.7 |
HIP 86867 |
16.16 |
| 2026-02-08 12:00 |
17:41:14.33 |
-77:14:23.1 |
HIP 86867 |
13.93 |
| 2026-02-09 00:00 |
17:41:40.42 |
-77:16:18.1 |
HIP 86867 |
11.76 |
| 2026-02-09 12:00 |
17:42:06.22 |
-77:18:13.7 |
HIP 86867 |
9.73 |
| 2026-02-10 00:00 |
17:42:31.73 |
-77:20:10.0 |
HIP 86867 |
7.92 |
| 2026-02-10 12:00 |
17:42:56.95 |
-77:22:06.8 |
HIP 86867 |
6.53 |
| 2026-02-11 00:00 |
17:43:21.88 |
-77:24:04.3 |
HIP 86867 |
5.84 |
| 2026-02-11 12:00 |
17:43:46.51 |
-77:26:02.5 |
HIP 86867 |
6.11 |
| 2026-02-12 00:00 |
17:44:10.83 |
-77:28:01.2 |
HIP 86867 |
7.23 |
| 2026-02-12 12:00 |
17:44:34.85 |
-77:30:00.6 |
HIP 86867 |
8.87 |
| 2026-02-13 00:00 |
17:44:58.55 |
-77:32:00.6 |
HIP 86867 |
10.80 |
| 2026-02-13 12:00 |
17:45:21.94 |
-77:34:01.1 |
HIP 86867 |
12.89 |
| 2026-02-14 00:00 |
17:45:45.01 |
-77:36:02.3 |
HIP 86867 |
15.07 |
| 2026-02-14 12:00 |
17:46:07.76 |
-77:38:04.1 |
HIP 86867 |
17.31 |
| 2026-02-15 00:00 |
17:46:30.18 |
-77:40:06.5 |
HIP 86867 |
19.58 |
| 2026-02-15 12:00 |
17:46:52.26 |
-77:42:09.5 |
HIP 86867 |
21.88 |
| 2026-02-16 00:00 |
17:47:14.01 |
-77:44:13.1 |
HIP 86867 |
24.20 |
| 2026-02-16 12:00 |
17:47:35.43 |
-77:46:17.3 |
HIP 86867 |
26.52 |
| 2026-02-17 00:00 |
17:47:56.49 |
-77:48:22.0 |
HIP 86973 |
28.59 |
| 2026-02-17 12:00 |
17:48:17.21 |
-77:50:27.3 |
HIP 86973 |
26.73 |
| 2026-02-18 00:00 |
17:48:37.57 |
-77:52:33.2 |
HIP 86973 |
24.95 |
| 2026-02-18 12:00 |
17:48:57.58 |
-77:54:39.7 |
HIP 86973 |
23.24 |
| 2026-02-19 00:00 |
17:49:17.22 |
-77:56:46.7 |
HIP 86973 |
21.64 |
| 2026-02-19 12:00 |
17:49:36.49 |
-77:58:54.3 |
HIP 86973 |
20.17 |
| 2026-02-20 00:00 |
17:49:55.40 |
-78:01:02.5 |
HIP 86973 |
18.85 |
| 2026-02-20 12:00 |
17:50:13.92 |
-78:03:11.2 |
HIP 86973 |
17.72 |
| 2026-02-21 00:00 |
17:50:32.07 |
-78:05:20.4 |
HIP 86973 |
16.82 |
| 2026-02-21 12:00 |
17:50:49.83 |
-78:07:30.2 |
HIP 86973 |
16.19 |
| 2026-02-22 00:00 |
17:51:07.20 |
-78:09:40.5 |
HIP 86973 |
15.85 |
| 2026-02-22 12:00 |
17:51:24.17 |
-78:11:51.3 |
HIP 86973 |
15.83 |
| 2026-02-23 00:00 |
17:51:40.75 |
-78:14:02.6 |
HIP 86973 |
16.13 |
| 2026-02-23 12:00 |
17:51:56.92 |
-78:16:14.5 |
HIP 86973 |
16.73 |
| 2026-02-24 00:00 |
17:52:12.68 |
-78:18:26.8 |
HIP 86973 |
17.60 |