C/2023 P1 (Nishimura)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/2023 P1 (Nishimura) |
| Type | C |
| Perihelion (tp_cal, UTC) | 2023-09-17T15:23:38.446080Z |
| Orbit solution date (soln_date, UTC) | 2024-08-08T14:27:14Z |
| Obs used | 638 |
| NEO | - |
| M1 | 12.200 |
| K1 | 8.000 |
| PC | - |
| Discovery observation (MPC, UTC) | 2023-08-11T18:26:41.856000Z |
| Discovery magnitude (MPC) | 11.00 T |
| Discovery observatory (MPC) | 247 · Roving Observer |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2023-09-08.0000000 |
| e | 0.99610274 |
| q (au) | 0.225152 |
| a (au) | 57.771776 |
| i (deg) | 132.476418 |
| Ω (om, deg) | 66.834552 |
| ω (w, deg) | 116.297994 |
| M (ma, deg) | 359.978359 |
Magnitude
Scatter + Global Linear
$$ M_a = (10.942 + 5.265\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 10.942 |
| n | 5.265 |
| gf | 0.997 |
| gb | -0.921 |
| k | 0.944 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) | End (UTC) | a | b |
|---|---|---|---|
| 2023-01-19 | 2023-09-16 | +0.1403 | +0.148 |
| 2023-09-18 | 2024-05-28 | -0.5521 | -1.485 |
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 | 08:12:49.35 | -31:25:34.5 | HIP 40296 | 13.77 |
| 2026-03-26 12:00 | 08:12:42.71 | -31:23:04.1 | HIP 40296 | 16.37 |
| 2026-03-27 00:00 | 08:12:36.20 | -31:20:33.6 | HIP 40296 | 19.03 |
| 2026-03-27 12:00 | 08:12:29.82 | -31:18:03.0 | HIP 40296 | 21.73 |
| 2026-03-28 00:00 | 08:12:23.56 | -31:15:32.4 | HIP 40296 | 24.44 |
| 2026-03-28 12:00 | 08:12:17.43 | -31:13:01.6 | HIP 40296 | 27.16 |
| 2026-03-29 00:00 | 08:12:11.42 | -31:10:30.8 | HIP 40028 | 26.43 |
| 2026-03-29 12:00 | 08:12:05.54 | -31:08:00.0 | HIP 40028 | 23.94 |
| 2026-03-30 00:00 | 08:11:59.79 | -31:05:29.1 | HIP 40028 | 21.55 |
| 2026-03-30 12:00 | 08:11:54.17 | -31:02:58.2 | HIP 40028 | 19.30 |
| 2026-03-31 00:00 | 08:11:48.67 | -31:00:27.3 | HIP 40028 | 17.22 |
| 2026-03-31 12:00 | 08:11:43.30 | -30:57:56.5 | HIP 40028 | 15.40 |
| 2026-04-01 00:00 | 08:11:38.05 | -30:55:25.6 | HIP 40028 | 13.91 |
| 2026-04-01 12:00 | 08:11:32.94 | -30:52:54.8 | HIP 40028 | 12.88 |
| 2026-04-02 00:00 | 08:11:27.94 | -30:50:24.0 | HIP 40028 | 12.41 |
| 2026-04-02 12:00 | 08:11:23.08 | -30:47:53.3 | HIP 40028 | 12.54 |
| 2026-04-03 00:00 | 08:11:18.33 | -30:45:22.6 | HIP 40028 | 13.27 |
| 2026-04-03 12:00 | 08:11:13.72 | -30:42:52.1 | HIP 40028 | 14.49 |
| 2026-04-04 00:00 | 08:11:09.23 | -30:40:21.6 | HIP 40028 | 16.08 |
| 2026-04-04 12:00 | 08:11:04.86 | -30:37:51.2 | HIP 40028 | 17.95 |
| 2026-04-05 00:00 | 08:11:00.62 | -30:35:20.9 | HIP 40138 | 19.25 |
| 2026-04-05 12:00 | 08:10:56.51 | -30:32:50.8 | HIP 40138 | 17.79 |
| 2026-04-06 00:00 | 08:10:52.52 | -30:30:20.8 | HIP 40138 | 16.62 |
| 2026-04-06 12:00 | 08:10:48.65 | -30:27:51.0 | HIP 40018 | 14.88 |
| 2026-04-07 00:00 | 08:10:44.91 | -30:25:21.3 | HIP 40018 | 12.26 |
| 2026-04-07 12:00 | 08:10:41.29 | -30:22:51.8 | HIP 40018 | 9.66 |
| 2026-04-08 00:00 | 08:10:37.79 | -30:20:22.5 | HIP 40018 | 7.08 |
| 2026-04-08 12:00 | 08:10:34.42 | -30:17:53.4 | HIP 40018 | 4.55 |
| 2026-04-09 00:00 | 08:10:31.17 | -30:15:24.5 | HIP 40018 | 2.17 |
| 2026-04-09 12:00 | 08:10:28.05 | -30:12:55.8 | HIP 40018 | 1.45 |
| 2026-04-10 00:00 | 08:10:25.05 | -30:10:27.3 | HIP 40018 | 3.55 |
| 2026-04-10 12:00 | 08:10:22.17 | -30:07:59.1 | HIP 40018 | 6.02 |
| 2026-04-11 00:00 | 08:10:19.41 | -30:05:31.1 | HIP 40018 | 8.52 |
| 2026-04-11 12:00 | 08:10:16.78 | -30:03:03.5 | HIP 40018 | 11.03 |
| 2026-04-12 00:00 | 08:10:14.26 | -30:00:36.0 | HIP 40018 | 13.54 |
| 2026-04-12 12:00 | 08:10:11.87 | -29:58:08.9 | HIP 39915 | 15.21 |
| 2026-04-13 00:00 | 08:10:09.60 | -29:55:42.1 | HIP 39915 | 13.97 |
| 2026-04-13 12:00 | 08:10:07.45 | -29:53:15.6 | HIP 39915 | 13.13 |
| 2026-04-14 00:00 | 08:10:05.42 | -29:50:49.4 | HIP 39915 | 12.74 |
| 2026-04-14 12:00 | 08:10:03.52 | -29:48:23.5 | HIP 39915 | 12.86 |
| 2026-04-15 00:00 | 08:10:01.73 | -29:45:58.0 | HIP 39915 | 13.46 |
| 2026-04-15 12:00 | 08:10:00.06 | -29:43:32.8 | HIP 39915 | 14.47 |
| 2026-04-16 00:00 | 08:09:58.51 | -29:41:08.0 | HIP 39915 | 15.81 |