C/2020 P1 (NEOWISE)
| Parameter |
Value |
| Designation |
C/2020 P1 (NEOWISE) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2020-10-20T04:17:44.208960Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:34:09Z |
| Obs used |
136 |
| NEO |
- |
| M1 |
15.300 |
| K1 |
5.250 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2020-08-02T15:00:32.832000Z |
| Discovery magnitude (MPC) |
19.00 R |
| Discovery observatory (MPC) |
C51 · WISE |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2020-09-09.0000000 |
| e |
1.00029689 |
| q (au) |
0.342183 |
| a (au) |
-1152.562177 |
| i (deg) |
45.053817 |
| Ω (om, deg) |
53.539366 |
| ω (w, deg) |
8.894962 |
| M (ma, deg) |
-0.001037 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.493 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.493 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.502 |
| 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 |
| 2020-08-02 |
2020-09-20 |
+1.5488 |
-0.350 |
| 2020-09-20 |
2020-09-28 |
-9.3291 |
-2.714 |
| 2020-09-28 |
2020-10-05 |
+0.5441 |
-0.302 |
| 2020-10-24 |
2020-12-09 |
+0.0258 |
-0.250 |
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 |
15:21:56.48 |
-12:58:58.9 |
HIP 75116 |
18.18 |
| 2026-02-03 12:00 |
15:21:57.67 |
-12:58:57.1 |
HIP 75116 |
18.42 |
| 2026-02-04 00:00 |
15:21:58.79 |
-12:58:55.1 |
HIP 75116 |
18.65 |
| 2026-02-04 12:00 |
15:21:59.85 |
-12:58:52.8 |
HIP 75116 |
18.88 |
| 2026-02-05 00:00 |
15:22:00.86 |
-12:58:50.2 |
HIP 75116 |
19.10 |
| 2026-02-05 12:00 |
15:22:01.80 |
-12:58:47.4 |
HIP 75116 |
19.30 |
| 2026-02-06 00:00 |
15:22:02.69 |
-12:58:44.4 |
HIP 75116 |
19.51 |
| 2026-02-06 12:00 |
15:22:03.51 |
-12:58:41.1 |
HIP 75116 |
19.70 |
| 2026-02-07 00:00 |
15:22:04.27 |
-12:58:37.6 |
HIP 75116 |
19.88 |
| 2026-02-07 12:00 |
15:22:04.97 |
-12:58:33.8 |
HIP 75116 |
20.05 |
| 2026-02-08 00:00 |
15:22:05.61 |
-12:58:29.8 |
HIP 75116 |
20.22 |
| 2026-02-08 12:00 |
15:22:06.19 |
-12:58:25.5 |
HIP 75116 |
20.37 |
| 2026-02-09 00:00 |
15:22:06.71 |
-12:58:21.0 |
HIP 75116 |
20.52 |
| 2026-02-09 12:00 |
15:22:07.17 |
-12:58:16.3 |
HIP 75116 |
20.66 |
| 2026-02-10 00:00 |
15:22:07.56 |
-12:58:11.3 |
HIP 75116 |
20.78 |
| 2026-02-10 12:00 |
15:22:07.90 |
-12:58:06.1 |
HIP 75116 |
20.90 |
| 2026-02-11 00:00 |
15:22:08.17 |
-12:58:00.6 |
HIP 75116 |
21.01 |
| 2026-02-11 12:00 |
15:22:08.38 |
-12:57:54.9 |
HIP 75116 |
21.11 |
| 2026-02-12 00:00 |
15:22:08.53 |
-12:57:48.9 |
HIP 75116 |
21.20 |
| 2026-02-12 12:00 |
15:22:08.62 |
-12:57:42.7 |
HIP 75116 |
21.28 |
| 2026-02-13 00:00 |
15:22:08.64 |
-12:57:36.3 |
HIP 75116 |
21.35 |
| 2026-02-13 12:00 |
15:22:08.60 |
-12:57:29.6 |
HIP 75116 |
21.41 |
| 2026-02-14 00:00 |
15:22:08.50 |
-12:57:22.7 |
HIP 75116 |
21.46 |
| 2026-02-14 12:00 |
15:22:08.34 |
-12:57:15.6 |
HIP 75116 |
21.50 |
| 2026-02-15 00:00 |
15:22:08.12 |
-12:57:08.2 |
HIP 75116 |
21.54 |
| 2026-02-15 12:00 |
15:22:07.83 |
-12:57:00.5 |
HIP 75116 |
21.57 |
| 2026-02-16 00:00 |
15:22:07.49 |
-12:56:52.7 |
HIP 75116 |
21.58 |
| 2026-02-16 12:00 |
15:22:07.08 |
-12:56:44.6 |
HIP 75116 |
21.59 |
| 2026-02-17 00:00 |
15:22:06.60 |
-12:56:36.2 |
HIP 75116 |
21.60 |
| 2026-02-17 12:00 |
15:22:06.07 |
-12:56:27.7 |
HIP 75116 |
21.59 |
| 2026-02-18 00:00 |
15:22:05.47 |
-12:56:18.9 |
HIP 75116 |
21.58 |
| 2026-02-18 12:00 |
15:22:04.81 |
-12:56:09.9 |
HIP 75116 |
21.56 |
| 2026-02-19 00:00 |
15:22:04.09 |
-12:56:00.6 |
HIP 75116 |
21.54 |
| 2026-02-19 12:00 |
15:22:03.30 |
-12:55:51.1 |
HIP 75116 |
21.51 |
| 2026-02-20 00:00 |
15:22:02.46 |
-12:55:41.4 |
HIP 75116 |
21.47 |
| 2026-02-20 12:00 |
15:22:01.55 |
-12:55:31.4 |
HIP 75116 |
21.43 |
| 2026-02-21 00:00 |
15:22:00.58 |
-12:55:21.3 |
HIP 75116 |
21.39 |
| 2026-02-21 12:00 |
15:21:59.55 |
-12:55:10.9 |
HIP 75116 |
21.34 |
| 2026-02-22 00:00 |
15:21:58.45 |
-12:55:00.2 |
HIP 75116 |
21.29 |
| 2026-02-22 12:00 |
15:21:57.29 |
-12:54:49.4 |
HIP 75116 |
21.23 |
| 2026-02-23 00:00 |
15:21:56.08 |
-12:54:38.3 |
HIP 75116 |
21.18 |
| 2026-02-23 12:00 |
15:21:54.80 |
-12:54:27.0 |
HIP 75116 |
21.12 |
| 2026-02-24 00:00 |
15:21:53.45 |
-12:54:15.5 |
HIP 75116 |
21.06 |