| Parameter |
Value |
| Designation |
C/2023 H1 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2024-11-28T15:51:32.506560Z |
| Orbit solution date (soln_date, UTC) |
2025-12-18T15:12:22Z |
| Obs used |
733 |
| NEO |
- |
| M1 |
6.300 |
| K1 |
12.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2023-04-17T08:21:30.268800Z |
| Discovery magnitude (MPC) |
20.80 w |
| Discovery observatory (MPC) |
F52 · Pan-STARRS 2, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2025-04-15.0000000 |
| e |
0.99412834 |
| q (au) |
4.447633 |
| a (au) |
757.474344 |
| i (deg) |
21.782467 |
| Ω (om, deg) |
292.646754 |
| ω (w, deg) |
333.755152 |
| M (ma, deg) |
0.006493 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.558 + 5.313\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.558 |
| n |
5.313 |
| gf |
1.000 |
| gb |
-0.963 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2023-04-17 |
2024-09-05 |
-3.7302 |
+3.621 |
| 2025-03-10 |
2025-11-15 |
-7.2442 |
+4.804 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
21:51:16.39 |
-02:09:23.8 |
HIP 107878 |
5.81 |
| 2026-03-26 12:00 |
21:51:36.18 |
-02:06:21.1 |
HIP 107878 |
8.54 |
| 2026-03-27 00:00 |
21:51:55.89 |
-02:03:18.4 |
HIP 107878 |
13.39 |
| 2026-03-27 12:00 |
21:52:15.52 |
-02:00:15.8 |
HIP 107878 |
18.76 |
| 2026-03-28 00:00 |
21:52:35.06 |
-01:57:13.2 |
HIP 107878 |
24.30 |
| 2026-03-28 12:00 |
21:52:54.52 |
-01:54:10.6 |
HIP 107878 |
29.91 |
| 2026-03-29 00:00 |
21:53:13.89 |
-01:51:08.1 |
HIP 107878 |
35.54 |
| 2026-03-29 12:00 |
21:53:33.18 |
-01:48:05.6 |
HIP 107939 |
38.07 |
| 2026-03-30 00:00 |
21:53:52.39 |
-01:45:03.2 |
HIP 108019 |
37.83 |
| 2026-03-30 12:00 |
21:54:11.51 |
-01:42:00.8 |
HIP 108019 |
37.00 |
| 2026-03-31 00:00 |
21:54:30.54 |
-01:38:58.5 |
HIP 108019 |
37.03 |
| 2026-03-31 12:00 |
21:54:49.49 |
-01:35:56.2 |
HIP 108019 |
37.89 |
| 2026-04-01 00:00 |
21:55:08.35 |
-01:32:54.1 |
HIP 108019 |
39.52 |
| 2026-04-01 12:00 |
21:55:27.13 |
-01:29:52.0 |
HIP 108019 |
41.83 |
| 2026-04-02 00:00 |
21:55:45.81 |
-01:26:49.9 |
HIP 108019 |
44.70 |
| 2026-04-02 12:00 |
21:56:04.41 |
-01:23:48.0 |
HIP 108362 |
40.19 |
| 2026-04-03 00:00 |
21:56:22.92 |
-01:20:46.1 |
HIP 108362 |
35.68 |
| 2026-04-03 12:00 |
21:56:41.34 |
-01:17:44.3 |
HIP 108362 |
31.51 |
| 2026-04-04 00:00 |
21:56:59.67 |
-01:14:42.6 |
HIP 108362 |
27.80 |
| 2026-04-04 12:00 |
21:57:17.91 |
-01:11:41.0 |
HIP 108362 |
24.77 |
| 2026-04-05 00:00 |
21:57:36.06 |
-01:08:39.5 |
HIP 108362 |
22.67 |
| 2026-04-05 12:00 |
21:57:54.12 |
-01:05:38.1 |
HIP 108362 |
21.76 |
| 2026-04-06 00:00 |
21:58:12.08 |
-01:02:36.8 |
HIP 108362 |
22.16 |
| 2026-04-06 12:00 |
21:58:29.96 |
-00:59:35.6 |
HIP 108362 |
23.80 |
| 2026-04-07 00:00 |
21:58:47.74 |
-00:56:34.5 |
HIP 108406 |
25.13 |
| 2026-04-07 12:00 |
21:59:05.43 |
-00:53:33.6 |
HIP 108406 |
26.33 |
| 2026-04-08 00:00 |
21:59:23.02 |
-00:50:32.8 |
HIP 108638 |
23.36 |
| 2026-04-08 12:00 |
21:59:40.52 |
-00:47:32.0 |
HIP 108638 |
18.12 |
| 2026-04-09 00:00 |
21:59:57.92 |
-00:44:31.5 |
HIP 108638 |
12.95 |
| 2026-04-09 12:00 |
22:00:15.23 |
-00:41:31.0 |
HIP 108638 |
7.95 |
| 2026-04-10 00:00 |
22:00:32.45 |
-00:38:30.7 |
HIP 108638 |
3.78 |
| 2026-04-10 12:00 |
22:00:49.56 |
-00:35:30.5 |
HIP 108638 |
4.49 |
| 2026-04-11 00:00 |
22:01:06.58 |
-00:32:30.5 |
HIP 108638 |
8.96 |
| 2026-04-11 12:00 |
22:01:23.50 |
-00:29:30.7 |
HIP 108762 |
12.81 |
| 2026-04-12 00:00 |
22:01:40.32 |
-00:26:30.9 |
HIP 108762 |
8.00 |
| 2026-04-12 12:00 |
22:01:57.04 |
-00:23:31.4 |
HIP 108762 |
4.13 |
| 2026-04-13 00:00 |
22:02:13.66 |
-00:20:32.0 |
HIP 108762 |
4.77 |
| 2026-04-13 12:00 |
22:02:30.19 |
-00:17:32.8 |
HIP 108762 |
8.97 |
| 2026-04-14 00:00 |
22:02:46.61 |
-00:14:33.8 |
HIP 108762 |
13.76 |
| 2026-04-14 12:00 |
22:03:02.93 |
-00:11:35.0 |
HIP 108844 |
15.86 |
| 2026-04-15 00:00 |
22:03:19.14 |
-00:08:36.3 |
HIP 108844 |
14.01 |
| 2026-04-15 12:00 |
22:03:35.26 |
-00:05:37.8 |
HIP 108844 |
13.83 |
| 2026-04-16 00:00 |
22:03:51.27 |
-00:02:39.6 |
HIP 108844 |
15.35 |