| Parameter |
Value |
| Designation |
C/2018 N1 (NEOWISE) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-08-01T23:35:12.114240Z |
| Orbit solution date (soln_date, UTC) |
2022-06-20T23:12:32Z |
| Obs used |
263 |
| NEO |
- |
| M1 |
14.800 |
| K1 |
11.750 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2018-07-02T08:53:36.384000Z |
| Discovery magnitude (MPC) |
16.00 R |
| Discovery observatory (MPC) |
C51 · WISE |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-07-23.0000000 |
| e |
0.99690168 |
| q (au) |
1.307382 |
| a (au) |
421.964782 |
| i (deg) |
159.444331 |
| Ω (om, deg) |
292.438182 |
| ω (w, deg) |
354.558421 |
| M (ma, deg) |
359.998865 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.856 + 5.455\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.856 |
| n |
5.455 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
0.957 |
| δ90 |
1.000 |
| 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 |
| 2017-12-15 |
2018-08-01 |
+5.8573 |
-2.511 |
| 2018-08-02 |
2018-10-06 |
-17.1024 |
-0.661 |
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 |
09:59:07.79 |
+24:56:33.1 |
HIP 48810 |
25.93 |
| 2026-03-26 12:00 |
09:59:02.35 |
+24:56:45.3 |
HIP 48810 |
24.85 |
| 2026-03-27 00:00 |
09:58:56.94 |
+24:56:57.3 |
HIP 48810 |
23.78 |
| 2026-03-27 12:00 |
09:58:51.58 |
+24:57:08.9 |
HIP 48810 |
22.75 |
| 2026-03-28 00:00 |
09:58:46.25 |
+24:57:20.2 |
HIP 48810 |
21.74 |
| 2026-03-28 12:00 |
09:58:40.95 |
+24:57:31.2 |
HIP 48810 |
20.75 |
| 2026-03-29 00:00 |
09:58:35.70 |
+24:57:41.9 |
HIP 48810 |
19.80 |
| 2026-03-29 12:00 |
09:58:30.49 |
+24:57:52.3 |
HIP 48810 |
18.88 |
| 2026-03-30 00:00 |
09:58:25.31 |
+24:58:02.4 |
HIP 48810 |
18.00 |
| 2026-03-30 12:00 |
09:58:20.18 |
+24:58:12.1 |
HIP 48810 |
17.16 |
| 2026-03-31 00:00 |
09:58:15.08 |
+24:58:21.5 |
HIP 48810 |
16.36 |
| 2026-03-31 12:00 |
09:58:10.02 |
+24:58:30.6 |
HIP 48810 |
15.61 |
| 2026-04-01 00:00 |
09:58:05.01 |
+24:58:39.4 |
HIP 48810 |
14.92 |
| 2026-04-01 12:00 |
09:58:00.03 |
+24:58:47.9 |
HIP 48810 |
14.28 |
| 2026-04-02 00:00 |
09:57:55.10 |
+24:58:56.1 |
HIP 48810 |
13.72 |
| 2026-04-02 12:00 |
09:57:50.21 |
+24:59:03.9 |
HIP 48810 |
13.22 |
| 2026-04-03 00:00 |
09:57:45.36 |
+24:59:11.4 |
HIP 48810 |
12.81 |
| 2026-04-03 12:00 |
09:57:40.55 |
+24:59:18.7 |
HIP 48810 |
12.47 |
| 2026-04-04 00:00 |
09:57:35.78 |
+24:59:25.6 |
HIP 48759 |
12.16 |
| 2026-04-04 12:00 |
09:57:31.06 |
+24:59:32.1 |
HIP 48759 |
11.11 |
| 2026-04-05 00:00 |
09:57:26.38 |
+24:59:38.4 |
HIP 48759 |
10.08 |
| 2026-04-05 12:00 |
09:57:21.74 |
+24:59:44.4 |
HIP 48759 |
9.07 |
| 2026-04-06 00:00 |
09:57:17.14 |
+24:59:50.0 |
HIP 48759 |
8.08 |
| 2026-04-06 12:00 |
09:57:12.59 |
+24:59:55.4 |
HIP 48759 |
7.12 |
| 2026-04-07 00:00 |
09:57:08.09 |
+25:00:00.4 |
HIP 48759 |
6.19 |
| 2026-04-07 12:00 |
09:57:03.62 |
+25:00:05.1 |
HIP 48759 |
5.30 |
| 2026-04-08 00:00 |
09:56:59.20 |
+25:00:09.5 |
HIP 48759 |
4.49 |
| 2026-04-08 12:00 |
09:56:54.83 |
+25:00:13.6 |
HIP 48759 |
3.77 |
| 2026-04-09 00:00 |
09:56:50.50 |
+25:00:17.3 |
HIP 48759 |
3.22 |
| 2026-04-09 12:00 |
09:56:46.21 |
+25:00:20.8 |
HIP 48759 |
2.91 |
| 2026-04-10 00:00 |
09:56:41.98 |
+25:00:23.9 |
HIP 48759 |
2.91 |
| 2026-04-10 12:00 |
09:56:37.78 |
+25:00:26.8 |
HIP 48759 |
3.21 |
| 2026-04-11 00:00 |
09:56:33.63 |
+25:00:29.3 |
HIP 48759 |
3.74 |
| 2026-04-11 12:00 |
09:56:29.53 |
+25:00:31.5 |
HIP 48759 |
4.40 |
| 2026-04-12 00:00 |
09:56:25.48 |
+25:00:33.4 |
HIP 48759 |
5.13 |
| 2026-04-12 12:00 |
09:56:21.47 |
+25:00:35.0 |
HIP 48759 |
5.91 |
| 2026-04-13 00:00 |
09:56:17.51 |
+25:00:36.3 |
HIP 48759 |
6.72 |
| 2026-04-13 12:00 |
09:56:13.59 |
+25:00:37.3 |
HIP 48759 |
7.54 |
| 2026-04-14 00:00 |
09:56:09.73 |
+25:00:38.0 |
HIP 48759 |
8.36 |
| 2026-04-14 12:00 |
09:56:05.91 |
+25:00:38.3 |
HIP 48759 |
9.19 |
| 2026-04-15 00:00 |
09:56:02.14 |
+25:00:38.4 |
HIP 48759 |
10.01 |
| 2026-04-15 12:00 |
09:55:58.41 |
+25:00:38.1 |
HIP 48759 |
10.82 |
| 2026-04-16 00:00 |
09:55:54.74 |
+25:00:37.6 |
HIP 48759 |
11.64 |