| Parameter |
Value |
| Designation |
C/1990 M1 (McNaught-Hughes) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1991-02-27T15:48:11.756160Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:38Z |
| Obs used |
49 |
| NEO |
- |
| M1 |
10.900 |
| K1 |
6.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1990-12-12.0000000 |
| e |
1.00128966 |
| q (au) |
2.682264 |
| a (au) |
-2079.821712 |
| i (deg) |
132.774960 |
| Ω (om, deg) |
233.206314 |
| ω (w, deg) |
18.169676 |
| M (ma, deg) |
-0.000807 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.670 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.670 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.997 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
03:34:18.34 |
+24:17:31.8 |
HIP 16639 |
4.03 |
| 2026-03-26 12:00 |
03:34:19.64 |
+24:17:33.1 |
HIP 16639 |
4.20 |
| 2026-03-27 00:00 |
03:34:20.97 |
+24:17:34.5 |
HIP 16639 |
4.39 |
| 2026-03-27 12:00 |
03:34:22.30 |
+24:17:35.9 |
HIP 16639 |
4.60 |
| 2026-03-28 00:00 |
03:34:23.65 |
+24:17:37.4 |
HIP 16639 |
4.81 |
| 2026-03-28 12:00 |
03:34:25.01 |
+24:17:38.9 |
HIP 16639 |
5.04 |
| 2026-03-29 00:00 |
03:34:26.39 |
+24:17:40.5 |
HIP 16639 |
5.28 |
| 2026-03-29 12:00 |
03:34:27.77 |
+24:17:42.2 |
HIP 16639 |
5.53 |
| 2026-03-30 00:00 |
03:34:29.18 |
+24:17:43.9 |
HIP 16639 |
5.79 |
| 2026-03-30 12:00 |
03:34:30.59 |
+24:17:45.7 |
HIP 16639 |
6.05 |
| 2026-03-31 00:00 |
03:34:32.02 |
+24:17:47.6 |
HIP 16639 |
6.33 |
| 2026-03-31 12:00 |
03:34:33.46 |
+24:17:49.5 |
HIP 16639 |
6.61 |
| 2026-04-01 00:00 |
03:34:34.91 |
+24:17:51.4 |
HIP 16639 |
6.89 |
| 2026-04-01 12:00 |
03:34:36.38 |
+24:17:53.4 |
HIP 16639 |
7.19 |
| 2026-04-02 00:00 |
03:34:37.86 |
+24:17:55.5 |
HIP 16639 |
7.49 |
| 2026-04-02 12:00 |
03:34:39.35 |
+24:17:57.6 |
HIP 16639 |
7.79 |
| 2026-04-03 00:00 |
03:34:40.86 |
+24:17:59.8 |
HIP 16639 |
8.10 |
| 2026-04-03 12:00 |
03:34:42.37 |
+24:18:02.1 |
HIP 16639 |
8.41 |
| 2026-04-04 00:00 |
03:34:43.90 |
+24:18:04.4 |
HIP 16639 |
8.73 |
| 2026-04-04 12:00 |
03:34:45.44 |
+24:18:06.8 |
HIP 16639 |
9.06 |
| 2026-04-05 00:00 |
03:34:46.99 |
+24:18:09.2 |
HIP 16639 |
9.39 |
| 2026-04-05 12:00 |
03:34:48.56 |
+24:18:11.6 |
HIP 16639 |
9.72 |
| 2026-04-06 00:00 |
03:34:50.13 |
+24:18:14.2 |
HIP 16639 |
10.06 |
| 2026-04-06 12:00 |
03:34:51.72 |
+24:18:16.8 |
HIP 16639 |
10.40 |
| 2026-04-07 00:00 |
03:34:53.32 |
+24:18:19.4 |
HIP 16639 |
10.74 |
| 2026-04-07 12:00 |
03:34:54.93 |
+24:18:22.1 |
HIP 16639 |
11.09 |
| 2026-04-08 00:00 |
03:34:56.55 |
+24:18:24.8 |
HIP 16639 |
11.44 |
| 2026-04-08 12:00 |
03:34:58.18 |
+24:18:27.6 |
HIP 16639 |
11.80 |
| 2026-04-09 00:00 |
03:34:59.82 |
+24:18:30.5 |
HIP 16664 |
12.03 |
| 2026-04-09 12:00 |
03:35:01.48 |
+24:18:33.4 |
HIP 16664 |
12.23 |
| 2026-04-10 00:00 |
03:35:03.14 |
+24:18:36.4 |
HIP 16664 |
12.45 |
| 2026-04-10 12:00 |
03:35:04.82 |
+24:18:39.4 |
HIP 16664 |
12.67 |
| 2026-04-11 00:00 |
03:35:06.50 |
+24:18:42.4 |
HIP 16664 |
12.90 |
| 2026-04-11 12:00 |
03:35:08.20 |
+24:18:45.6 |
HIP 16664 |
13.14 |
| 2026-04-12 00:00 |
03:35:09.91 |
+24:18:48.7 |
HIP 16664 |
13.38 |
| 2026-04-12 12:00 |
03:35:11.62 |
+24:18:52.0 |
HIP 16664 |
13.64 |
| 2026-04-13 00:00 |
03:35:13.35 |
+24:18:55.2 |
HIP 16664 |
13.90 |
| 2026-04-13 12:00 |
03:35:15.09 |
+24:18:58.6 |
HIP 16664 |
14.17 |
| 2026-04-14 00:00 |
03:35:16.83 |
+24:19:01.9 |
HIP 16664 |
14.45 |
| 2026-04-14 12:00 |
03:35:18.59 |
+24:19:05.4 |
HIP 16664 |
14.73 |
| 2026-04-15 00:00 |
03:35:20.35 |
+24:19:08.8 |
HIP 16664 |
15.02 |
| 2026-04-15 12:00 |
03:35:22.13 |
+24:19:12.3 |
HIP 16664 |
15.32 |
| 2026-04-16 00:00 |
03:35:23.91 |
+24:19:15.9 |
HIP 16664 |
15.63 |