| Parameter |
Value |
| Designation |
C/2018 V1 (Machholz-Fujikawa-Iwamoto) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-12-03T12:11:39.986880Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:46Z |
| Obs used |
750 |
| NEO |
- |
| M1 |
12.800 |
| K1 |
6.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-11-16.0000000 |
| e |
1.00039061 |
| q (au) |
0.386955 |
| a (au) |
-990.650949 |
| i (deg) |
143.987960 |
| Ω (om, deg) |
128.722091 |
| ω (w, deg) |
88.774914 |
| M (ma, deg) |
-0.000553 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.888 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.888 |
| n |
2.000 |
| gf |
0.800 |
| gb |
-1.000 |
| k |
0.800 |
| 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 |
| 2018-11-08 |
2018-11-17 |
-1.9894 |
-0.711 |
| 2018-11-17 |
2018-12-01 |
+3.0505 |
+1.813 |
| 2018-12-04 |
2018-12-17 |
+11.8201 |
+5.111 |
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 |
14:47:31.76 |
-51:27:46.3 |
HIP 72386 |
8.18 |
| 2026-09-20 12:00 |
14:47:37.11 |
-51:27:26.2 |
HIP 72386 |
8.04 |
| 2026-09-21 00:00 |
14:47:42.51 |
-51:27:06.5 |
HIP 72386 |
7.99 |
| 2026-09-21 12:00 |
14:47:47.95 |
-51:26:47.1 |
HIP 72386 |
8.04 |
| 2026-09-22 00:00 |
14:47:53.44 |
-51:26:28.1 |
HIP 72386 |
8.18 |
| 2026-09-22 12:00 |
14:47:58.97 |
-51:26:09.5 |
HIP 72386 |
8.41 |
| 2026-09-23 00:00 |
14:48:04.55 |
-51:25:51.4 |
HIP 72386 |
8.72 |
| 2026-09-23 12:00 |
14:48:10.17 |
-51:25:33.6 |
HIP 72386 |
9.11 |
| 2026-09-24 00:00 |
14:48:15.83 |
-51:25:16.2 |
HIP 72386 |
9.57 |
| 2026-09-24 12:00 |
14:48:21.53 |
-51:24:59.1 |
HIP 72386 |
10.09 |
| 2026-09-25 00:00 |
14:48:27.28 |
-51:24:42.5 |
HIP 72386 |
10.66 |
| 2026-09-25 12:00 |
14:48:33.06 |
-51:24:26.3 |
HIP 72386 |
11.28 |
| 2026-09-26 00:00 |
14:48:38.89 |
-51:24:10.5 |
HIP 72517 |
11.41 |
| 2026-09-26 12:00 |
14:48:44.76 |
-51:23:55.0 |
HIP 72517 |
10.88 |
| 2026-09-27 00:00 |
14:48:50.67 |
-51:23:40.0 |
HIP 72517 |
10.40 |
| 2026-09-27 12:00 |
14:48:56.62 |
-51:23:25.3 |
HIP 72517 |
9.98 |
| 2026-09-28 00:00 |
14:49:02.61 |
-51:23:11.1 |
HIP 72517 |
9.63 |
| 2026-09-28 12:00 |
14:49:08.64 |
-51:22:57.2 |
HIP 72517 |
9.36 |
| 2026-09-29 00:00 |
14:49:14.71 |
-51:22:43.7 |
HIP 72517 |
9.17 |
| 2026-09-29 12:00 |
14:49:20.81 |
-51:22:30.6 |
HIP 72517 |
9.07 |
| 2026-09-30 00:00 |
14:49:26.96 |
-51:22:18.0 |
HIP 72517 |
9.07 |
| 2026-09-30 12:00 |
14:49:33.14 |
-51:22:05.7 |
HIP 72517 |
9.17 |
| 2026-10-01 00:00 |
14:49:39.36 |
-51:21:53.8 |
HIP 72517 |
9.37 |
| 2026-10-01 12:00 |
14:49:45.62 |
-51:21:42.3 |
HIP 72517 |
9.66 |
| 2026-10-02 00:00 |
14:49:51.91 |
-51:21:31.2 |
HIP 72517 |
10.03 |
| 2026-10-02 12:00 |
14:49:58.24 |
-51:21:20.5 |
HIP 72517 |
10.48 |
| 2026-10-03 00:00 |
14:50:04.60 |
-51:21:10.2 |
HIP 72517 |
11.00 |
| 2026-10-03 12:00 |
14:50:11.01 |
-51:21:00.3 |
HIP 72517 |
11.58 |
| 2026-10-04 00:00 |
14:50:17.44 |
-51:20:50.8 |
HIP 72517 |
12.22 |
| 2026-10-04 12:00 |
14:50:23.91 |
-51:20:41.6 |
HIP 72517 |
12.90 |
| 2026-10-05 00:00 |
14:50:30.42 |
-51:20:32.9 |
HIP 72517 |
13.62 |
| 2026-10-05 12:00 |
14:50:36.96 |
-51:20:24.6 |
HIP 72517 |
14.38 |
| 2026-10-06 00:00 |
14:50:43.53 |
-51:20:16.7 |
HIP 72517 |
15.16 |
| 2026-10-06 12:00 |
14:50:50.13 |
-51:20:09.2 |
HIP 72517 |
15.98 |
| 2026-10-07 00:00 |
14:50:56.77 |
-51:20:02.1 |
HIP 72517 |
16.82 |
| 2026-10-07 12:00 |
14:51:03.44 |
-51:19:55.4 |
HIP 72517 |
17.68 |
| 2026-10-08 00:00 |
14:51:10.14 |
-51:19:49.0 |
HIP 72812 |
18.14 |
| 2026-10-08 12:00 |
14:51:16.87 |
-51:19:43.1 |
HIP 72812 |
17.24 |
| 2026-10-09 00:00 |
14:51:23.63 |
-51:19:37.6 |
HIP 72812 |
16.34 |
| 2026-10-09 12:00 |
14:51:30.43 |
-51:19:32.5 |
HIP 72812 |
15.47 |
| 2026-10-10 00:00 |
14:51:37.25 |
-51:19:27.8 |
HIP 72812 |
14.61 |
| 2026-10-10 12:00 |
14:51:44.10 |
-51:19:23.5 |
HIP 72812 |
13.77 |
| 2026-10-11 00:00 |
14:51:50.98 |
-51:19:19.5 |
HIP 72812 |
12.95 |