| Parameter |
Value |
| Designation |
C/2023 H1 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2024-11-28T15:41:17.917440Z |
| Orbit solution date (soln_date, UTC) |
2026-09-21T07:12:11Z |
| Obs used |
779 |
| NEO |
- |
| M1 |
4.600 |
| K1 |
14.500 |
| 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) |
2025-05-03.0000000 |
| e |
0.99413830 |
| q (au) |
4.447624 |
| a (au) |
758.759682 |
| i (deg) |
21.782525 |
| Ω (om, deg) |
292.646745 |
| ω (w, deg) |
333.754079 |
| M (ma, deg) |
0.007326 |
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) |
| 2026-09-20 00:00 |
21:53:31.11 |
+06:12:00.0 |
HIP 108038 |
13.23 |
| 2026-09-20 12:00 |
21:53:22.51 |
+06:11:05.6 |
HIP 108038 |
13.82 |
| 2026-09-21 00:00 |
21:53:14.02 |
+06:10:11.2 |
HIP 108038 |
14.75 |
| 2026-09-21 12:00 |
21:53:05.63 |
+06:09:16.6 |
HIP 108038 |
15.96 |
| 2026-09-22 00:00 |
21:52:57.34 |
+06:08:21.9 |
HIP 108038 |
17.38 |
| 2026-09-22 12:00 |
21:52:49.16 |
+06:07:26.9 |
HIP 108038 |
18.95 |
| 2026-09-23 00:00 |
21:52:41.08 |
+06:06:31.9 |
HIP 108038 |
20.64 |
| 2026-09-23 12:00 |
21:52:33.11 |
+06:05:36.8 |
HIP 108038 |
22.40 |
| 2026-09-24 00:00 |
21:52:25.25 |
+06:04:41.5 |
HIP 108038 |
24.22 |
| 2026-09-24 12:00 |
21:52:17.50 |
+06:03:46.1 |
HIP 108038 |
26.07 |
| 2026-09-25 00:00 |
21:52:09.86 |
+06:02:50.7 |
HIP 107948 |
25.23 |
| 2026-09-25 12:00 |
21:52:02.32 |
+06:01:55.1 |
HIP 107948 |
24.38 |
| 2026-09-26 00:00 |
21:51:54.90 |
+06:00:59.5 |
HIP 107948 |
23.69 |
| 2026-09-26 12:00 |
21:51:47.59 |
+06:00:03.9 |
HIP 107948 |
23.15 |
| 2026-09-27 00:00 |
21:51:40.40 |
+05:59:08.2 |
HIP 107948 |
22.77 |
| 2026-09-27 12:00 |
21:51:33.32 |
+05:58:12.5 |
HIP 107948 |
22.55 |
| 2026-09-28 00:00 |
21:51:26.35 |
+05:57:16.7 |
HIP 107948 |
22.50 |
| 2026-09-28 12:00 |
21:51:19.50 |
+05:56:21.0 |
HIP 107948 |
22.60 |
| 2026-09-29 00:00 |
21:51:12.76 |
+05:55:25.2 |
HIP 107948 |
22.85 |
| 2026-09-29 12:00 |
21:51:06.15 |
+05:54:29.5 |
HIP 107948 |
23.23 |
| 2026-09-30 00:00 |
21:50:59.65 |
+05:53:33.8 |
HIP 107948 |
23.74 |
| 2026-09-30 12:00 |
21:50:53.27 |
+05:52:38.1 |
HIP 107948 |
24.35 |
| 2026-10-01 00:00 |
21:50:47.01 |
+05:51:42.4 |
HIP 107948 |
25.06 |
| 2026-10-01 12:00 |
21:50:40.87 |
+05:50:46.8 |
HIP 107948 |
25.86 |
| 2026-10-02 00:00 |
21:50:34.85 |
+05:49:51.3 |
HIP 107948 |
26.72 |
| 2026-10-02 12:00 |
21:50:28.95 |
+05:48:55.9 |
HIP 107677 |
26.27 |
| 2026-10-03 00:00 |
21:50:23.18 |
+05:48:00.5 |
HIP 107677 |
24.92 |
| 2026-10-03 12:00 |
21:50:17.53 |
+05:47:05.2 |
HIP 107677 |
23.65 |
| 2026-10-04 00:00 |
21:50:12.00 |
+05:46:10.1 |
HIP 107677 |
22.45 |
| 2026-10-04 12:00 |
21:50:06.60 |
+05:45:15.1 |
HIP 107677 |
21.35 |
| 2026-10-05 00:00 |
21:50:01.33 |
+05:44:20.2 |
HIP 107677 |
20.35 |
| 2026-10-05 12:00 |
21:49:56.18 |
+05:43:25.4 |
HIP 107677 |
19.46 |
| 2026-10-06 00:00 |
21:49:51.16 |
+05:42:30.8 |
HIP 107677 |
18.68 |
| 2026-10-06 12:00 |
21:49:46.26 |
+05:41:36.3 |
HIP 107677 |
18.03 |
| 2026-10-07 00:00 |
21:49:41.50 |
+05:40:42.1 |
HIP 107677 |
17.51 |
| 2026-10-07 12:00 |
21:49:36.86 |
+05:39:48.0 |
HIP 107677 |
17.13 |
| 2026-10-08 00:00 |
21:49:32.36 |
+05:38:54.1 |
HIP 107677 |
16.89 |
| 2026-10-08 12:00 |
21:49:27.98 |
+05:38:00.5 |
HIP 107677 |
16.79 |
| 2026-10-09 00:00 |
21:49:23.74 |
+05:37:07.0 |
HIP 107677 |
16.82 |
| 2026-10-09 12:00 |
21:49:19.63 |
+05:36:13.8 |
HIP 107677 |
16.98 |
| 2026-10-10 00:00 |
21:49:15.65 |
+05:35:20.8 |
HIP 107677 |
17.26 |
| 2026-10-10 12:00 |
21:49:11.80 |
+05:34:28.1 |
HIP 107677 |
17.64 |
| 2026-10-11 00:00 |
21:49:08.09 |
+05:33:35.7 |
HIP 107677 |
18.11 |