| Parameter |
Value |
| Designation |
C/2023 H1 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2024-11-28T15:47:31.113600Z |
| Orbit solution date (soln_date, UTC) |
2026-07-28T14:12:16Z |
| Obs used |
743 |
| NEO |
- |
| M1 |
5.100 |
| K1 |
13.750 |
| 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) |
2025-04-21.0000000 |
| e |
0.99413533 |
| q (au) |
4.447632 |
| a (au) |
758.377491 |
| i (deg) |
21.782487 |
| Ω (om, deg) |
292.646751 |
| ω (w, deg) |
333.754736 |
| M (ma, deg) |
0.006765 |
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) |
| 2026-07-29 00:00 |
22:13:04.55 |
+06:51:57.8 |
HIP 109582 |
17.43 |
| 2026-07-29 12:00 |
22:12:54.26 |
+06:52:22.8 |
HIP 109582 |
14.85 |
| 2026-07-30 00:00 |
22:12:43.89 |
+06:52:46.7 |
HIP 109582 |
12.25 |
| 2026-07-30 12:00 |
22:12:33.45 |
+06:53:09.6 |
HIP 109582 |
9.64 |
| 2026-07-31 00:00 |
22:12:22.94 |
+06:53:31.3 |
HIP 109582 |
7.01 |
| 2026-07-31 12:00 |
22:12:12.36 |
+06:53:51.9 |
HIP 109582 |
4.38 |
| 2026-08-01 00:00 |
22:12:01.72 |
+06:54:11.5 |
HIP 109582 |
1.79 |
| 2026-08-01 12:00 |
22:11:51.00 |
+06:54:30.0 |
HIP 109582 |
1.17 |
| 2026-08-02 00:00 |
22:11:40.22 |
+06:54:47.3 |
HIP 109582 |
3.73 |
| 2026-08-02 12:00 |
22:11:29.38 |
+06:55:03.6 |
HIP 109530 |
5.99 |
| 2026-08-03 00:00 |
22:11:18.48 |
+06:55:18.8 |
HIP 109530 |
5.08 |
| 2026-08-03 12:00 |
22:11:07.51 |
+06:55:33.0 |
HIP 109530 |
5.50 |
| 2026-08-04 00:00 |
22:10:56.49 |
+06:55:46.0 |
HIP 109530 |
7.04 |
| 2026-08-04 12:00 |
22:10:45.41 |
+06:55:58.0 |
HIP 109530 |
9.17 |
| 2026-08-05 00:00 |
22:10:34.27 |
+06:56:08.9 |
HIP 109530 |
11.56 |
| 2026-08-05 12:00 |
22:10:23.08 |
+06:56:18.7 |
HIP 109530 |
14.10 |
| 2026-08-06 00:00 |
22:10:11.83 |
+06:56:27.5 |
HIP 109530 |
16.72 |
| 2026-08-06 12:00 |
22:10:00.54 |
+06:56:35.2 |
HIP 109530 |
19.40 |
| 2026-08-07 00:00 |
22:09:49.19 |
+06:56:41.8 |
HIP 109530 |
22.12 |
| 2026-08-07 12:00 |
22:09:37.80 |
+06:56:47.4 |
HIP 109530 |
24.86 |
| 2026-08-08 00:00 |
22:09:26.36 |
+06:56:51.9 |
HIP 109309 |
25.16 |
| 2026-08-08 12:00 |
22:09:14.88 |
+06:56:55.4 |
HIP 109309 |
24.10 |
| 2026-08-09 00:00 |
22:09:03.36 |
+06:56:57.9 |
HIP 109309 |
23.36 |
| 2026-08-09 12:00 |
22:08:51.79 |
+06:56:59.3 |
HIP 109309 |
22.97 |
| 2026-08-10 00:00 |
22:08:40.19 |
+06:56:59.6 |
HIP 109309 |
22.95 |
| 2026-08-10 12:00 |
22:08:28.55 |
+06:56:59.0 |
HIP 109309 |
23.31 |
| 2026-08-11 00:00 |
22:08:16.87 |
+06:56:57.3 |
HIP 109309 |
24.03 |
| 2026-08-11 12:00 |
22:08:05.16 |
+06:56:54.6 |
HIP 109309 |
25.09 |
| 2026-08-12 00:00 |
22:07:53.42 |
+06:56:50.8 |
HIP 109309 |
26.44 |
| 2026-08-12 12:00 |
22:07:41.65 |
+06:56:46.1 |
HIP 109309 |
28.05 |
| 2026-08-13 00:00 |
22:07:29.86 |
+06:56:40.4 |
HIP 109076 |
25.57 |
| 2026-08-13 12:00 |
22:07:18.03 |
+06:56:33.7 |
HIP 109076 |
22.66 |
| 2026-08-14 00:00 |
22:07:06.19 |
+06:56:26.0 |
HIP 109076 |
19.77 |
| 2026-08-14 12:00 |
22:06:54.32 |
+06:56:17.3 |
HIP 109076 |
16.88 |
| 2026-08-15 00:00 |
22:06:42.43 |
+06:56:07.6 |
HIP 109076 |
14.03 |
| 2026-08-15 12:00 |
22:06:30.53 |
+06:55:57.0 |
HIP 109076 |
11.22 |
| 2026-08-16 00:00 |
22:06:18.61 |
+06:55:45.4 |
HIP 109076 |
8.52 |
| 2026-08-16 12:00 |
22:06:06.67 |
+06:55:32.9 |
HIP 109076 |
6.08 |
| 2026-08-17 00:00 |
22:05:54.73 |
+06:55:19.5 |
HIP 109076 |
4.37 |
| 2026-08-17 12:00 |
22:05:42.77 |
+06:55:05.1 |
HIP 109076 |
4.37 |
| 2026-08-18 00:00 |
22:05:30.80 |
+06:54:49.8 |
HIP 109076 |
6.07 |
| 2026-08-18 12:00 |
22:05:18.83 |
+06:54:33.6 |
HIP 109076 |
8.52 |
| 2026-08-19 00:00 |
22:05:06.86 |
+06:54:16.5 |
HIP 109076 |
11.24 |