| 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) |
| 2026-05-12 00:00 |
09:53:52.71 |
+24:53:36.0 |
HIP 48642 |
22.63 |
| 2026-05-12 12:00 |
09:53:51.71 |
+24:53:21.0 |
HIP 48642 |
22.63 |
| 2026-05-13 00:00 |
09:53:50.77 |
+24:53:05.7 |
HIP 48642 |
22.62 |
| 2026-05-13 12:00 |
09:53:49.87 |
+24:52:50.2 |
HIP 48642 |
22.60 |
| 2026-05-14 00:00 |
09:53:49.02 |
+24:52:34.5 |
HIP 48642 |
22.58 |
| 2026-05-14 12:00 |
09:53:48.23 |
+24:52:18.5 |
HIP 48642 |
22.56 |
| 2026-05-15 00:00 |
09:53:47.49 |
+24:52:02.3 |
HIP 48642 |
22.52 |
| 2026-05-15 12:00 |
09:53:46.79 |
+24:51:45.8 |
HIP 48642 |
22.48 |
| 2026-05-16 00:00 |
09:53:46.15 |
+24:51:29.2 |
HIP 48642 |
22.43 |
| 2026-05-16 12:00 |
09:53:45.56 |
+24:51:12.3 |
HIP 48642 |
22.38 |
| 2026-05-17 00:00 |
09:53:45.02 |
+24:50:55.2 |
HIP 48642 |
22.32 |
| 2026-05-17 12:00 |
09:53:44.53 |
+24:50:37.8 |
HIP 48642 |
22.25 |
| 2026-05-18 00:00 |
09:53:44.09 |
+24:50:20.3 |
HIP 48642 |
22.17 |
| 2026-05-18 12:00 |
09:53:43.70 |
+24:50:02.5 |
HIP 48642 |
22.08 |
| 2026-05-19 00:00 |
09:53:43.36 |
+24:49:44.5 |
HIP 48642 |
21.99 |
| 2026-05-19 12:00 |
09:53:43.07 |
+24:49:26.3 |
HIP 48642 |
21.89 |
| 2026-05-20 00:00 |
09:53:42.84 |
+24:49:07.9 |
HIP 48642 |
21.78 |
| 2026-05-20 12:00 |
09:53:42.65 |
+24:48:49.2 |
HIP 48642 |
21.67 |
| 2026-05-21 00:00 |
09:53:42.51 |
+24:48:30.4 |
HIP 48642 |
21.54 |
| 2026-05-21 12:00 |
09:53:42.42 |
+24:48:11.3 |
HIP 48642 |
21.41 |
| 2026-05-22 00:00 |
09:53:42.37 |
+24:47:52.1 |
HIP 48642 |
21.27 |
| 2026-05-22 12:00 |
09:53:42.38 |
+24:47:32.6 |
HIP 48642 |
21.13 |
| 2026-05-23 00:00 |
09:53:42.44 |
+24:47:13.0 |
HIP 48642 |
20.98 |
| 2026-05-23 12:00 |
09:53:42.55 |
+24:46:53.1 |
HIP 48642 |
20.81 |
| 2026-05-24 00:00 |
09:53:42.70 |
+24:46:33.0 |
HIP 48642 |
20.65 |
| 2026-05-24 12:00 |
09:53:42.90 |
+24:46:12.8 |
HIP 48642 |
20.47 |
| 2026-05-25 00:00 |
09:53:43.15 |
+24:45:52.3 |
HIP 48642 |
20.29 |
| 2026-05-25 12:00 |
09:53:43.45 |
+24:45:31.7 |
HIP 48642 |
20.10 |
| 2026-05-26 00:00 |
09:53:43.80 |
+24:45:10.9 |
HIP 48642 |
19.90 |
| 2026-05-26 12:00 |
09:53:44.20 |
+24:44:49.8 |
HIP 48642 |
19.70 |
| 2026-05-27 00:00 |
09:53:44.64 |
+24:44:28.6 |
HIP 48642 |
19.49 |
| 2026-05-27 12:00 |
09:53:45.13 |
+24:44:07.2 |
HIP 48642 |
19.27 |
| 2026-05-28 00:00 |
09:53:45.67 |
+24:43:45.7 |
HIP 48642 |
19.05 |
| 2026-05-28 12:00 |
09:53:46.25 |
+24:43:23.9 |
HIP 48642 |
18.82 |
| 2026-05-29 00:00 |
09:53:46.89 |
+24:43:02.0 |
HIP 48642 |
18.58 |
| 2026-05-29 12:00 |
09:53:47.57 |
+24:42:39.8 |
HIP 48642 |
18.34 |
| 2026-05-30 00:00 |
09:53:48.29 |
+24:42:17.6 |
HIP 48642 |
18.10 |
| 2026-05-30 12:00 |
09:53:49.06 |
+24:41:55.1 |
HIP 48642 |
17.85 |
| 2026-05-31 00:00 |
09:53:49.88 |
+24:41:32.5 |
HIP 48642 |
17.59 |
| 2026-05-31 12:00 |
09:53:50.75 |
+24:41:09.6 |
HIP 48642 |
17.33 |
| 2026-06-01 00:00 |
09:53:51.66 |
+24:40:46.7 |
HIP 48642 |
17.06 |
| 2026-06-01 12:00 |
09:53:52.61 |
+24:40:23.5 |
HIP 48642 |
16.80 |
| 2026-06-02 00:00 |
09:53:53.62 |
+24:40:00.2 |
HIP 48642 |
16.53 |