| 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 |
-0.500 |
| 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 |
+1.4276 |
-0.325 |
| 2020-09-20 |
2020-10-05 |
-8.5024 |
-2.547 |
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 |
15:00:18.25 |
-12:06:13.9 |
HIP 73445 |
14.16 |
| 2026-09-20 12:00 |
15:00:22.48 |
-12:06:41.2 |
HIP 73445 |
14.41 |
| 2026-09-21 00:00 |
15:00:26.74 |
-12:07:08.7 |
HIP 73445 |
14.74 |
| 2026-09-21 12:00 |
15:00:31.04 |
-12:07:36.2 |
HIP 73445 |
15.15 |
| 2026-09-22 00:00 |
15:00:35.37 |
-12:08:03.9 |
HIP 73445 |
15.63 |
| 2026-09-22 12:00 |
15:00:39.74 |
-12:08:31.6 |
HIP 73445 |
16.19 |
| 2026-09-23 00:00 |
15:00:44.15 |
-12:08:59.5 |
HIP 73445 |
16.81 |
| 2026-09-23 12:00 |
15:00:48.59 |
-12:09:27.4 |
HIP 73445 |
17.49 |
| 2026-09-24 00:00 |
15:00:53.07 |
-12:09:55.4 |
HIP 73444 |
17.85 |
| 2026-09-24 12:00 |
15:00:57.58 |
-12:10:23.5 |
HIP 73444 |
17.77 |
| 2026-09-25 00:00 |
15:01:02.12 |
-12:10:51.7 |
HIP 73444 |
17.78 |
| 2026-09-25 12:00 |
15:01:06.70 |
-12:11:19.9 |
HIP 73444 |
17.87 |
| 2026-09-26 00:00 |
15:01:11.31 |
-12:11:48.3 |
HIP 73444 |
18.05 |
| 2026-09-26 12:00 |
15:01:15.95 |
-12:12:16.7 |
HIP 73444 |
18.31 |
| 2026-09-27 00:00 |
15:01:20.63 |
-12:12:45.2 |
HIP 73444 |
18.66 |
| 2026-09-27 12:00 |
15:01:25.34 |
-12:13:13.8 |
HIP 73444 |
19.08 |
| 2026-09-28 00:00 |
15:01:30.08 |
-12:13:42.4 |
HIP 73594 |
19.04 |
| 2026-09-28 12:00 |
15:01:34.86 |
-12:14:11.1 |
HIP 73594 |
17.82 |
| 2026-09-29 00:00 |
15:01:39.66 |
-12:14:39.9 |
HIP 73594 |
16.59 |
| 2026-09-29 12:00 |
15:01:44.50 |
-12:15:08.8 |
HIP 73594 |
15.37 |
| 2026-09-30 00:00 |
15:01:49.37 |
-12:15:37.7 |
HIP 73594 |
14.15 |
| 2026-09-30 12:00 |
15:01:54.27 |
-12:16:06.7 |
HIP 73594 |
12.93 |
| 2026-10-01 00:00 |
15:01:59.20 |
-12:16:35.8 |
HIP 73594 |
11.72 |
| 2026-10-01 12:00 |
15:02:04.16 |
-12:17:04.9 |
HIP 73594 |
10.53 |
| 2026-10-02 00:00 |
15:02:09.15 |
-12:17:34.1 |
HIP 73594 |
9.37 |
| 2026-10-02 12:00 |
15:02:14.17 |
-12:18:03.3 |
HIP 73594 |
8.24 |
| 2026-10-03 00:00 |
15:02:19.22 |
-12:18:32.6 |
HIP 73594 |
7.17 |
| 2026-10-03 12:00 |
15:02:24.30 |
-12:19:02.0 |
HIP 73594 |
6.21 |
| 2026-10-04 00:00 |
15:02:29.41 |
-12:19:31.4 |
HIP 73594 |
5.40 |
| 2026-10-04 12:00 |
15:02:34.55 |
-12:20:00.9 |
HIP 73594 |
4.83 |
| 2026-10-05 00:00 |
15:02:39.71 |
-12:20:30.4 |
HIP 73594 |
4.60 |
| 2026-10-05 12:00 |
15:02:44.91 |
-12:21:00.0 |
HIP 73594 |
4.76 |
| 2026-10-06 00:00 |
15:02:50.13 |
-12:21:29.6 |
HIP 73594 |
5.28 |
| 2026-10-06 12:00 |
15:02:55.37 |
-12:21:59.3 |
HIP 73594 |
6.08 |
| 2026-10-07 00:00 |
15:03:00.65 |
-12:22:29.0 |
HIP 73594 |
7.07 |
| 2026-10-07 12:00 |
15:03:05.95 |
-12:22:58.7 |
HIP 73594 |
8.17 |
| 2026-10-08 00:00 |
15:03:11.28 |
-12:23:28.5 |
HIP 73594 |
9.36 |
| 2026-10-08 12:00 |
15:03:16.63 |
-12:23:58.3 |
HIP 73594 |
10.60 |
| 2026-10-09 00:00 |
15:03:22.01 |
-12:24:28.2 |
HIP 73594 |
11.88 |
| 2026-10-09 12:00 |
15:03:27.41 |
-12:24:58.1 |
HIP 73594 |
13.20 |
| 2026-10-10 00:00 |
15:03:32.84 |
-12:25:28.1 |
HIP 73594 |
14.54 |
| 2026-10-10 12:00 |
15:03:38.30 |
-12:25:58.0 |
HIP 73594 |
15.89 |
| 2026-10-11 00:00 |
15:03:43.77 |
-12:26:28.0 |
HIP 73594 |
17.27 |