| Parameter |
Value |
| Designation |
C/1998 M4 (LINEAR) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1997-12-10T02:48:12.064320Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:53Z |
| Obs used |
116 |
| NEO |
- |
| M1 |
9.500 |
| K1 |
10.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1998-07-03.0000000 |
| e |
0.99738677 |
| q (au) |
2.600017 |
| a (au) |
994.943592 |
| i (deg) |
154.571097 |
| Ω (om, deg) |
92.922669 |
| ω (w, deg) |
106.286301 |
| M (ma, deg) |
0.006434 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.999 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.999 |
| n |
2.000 |
| gf |
0.812 |
| gb |
-0.935 |
| k |
1.000 |
| δ90 |
2.369 |
| 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) |
| 2026-07-29 00:00 |
12:03:48.00 |
-27:40:09.9 |
HIP 58907 |
13.14 |
| 2026-07-29 12:00 |
12:03:49.27 |
-27:40:03.4 |
HIP 58907 |
12.87 |
| 2026-07-30 00:00 |
12:03:50.57 |
-27:39:57.1 |
HIP 58907 |
12.59 |
| 2026-07-30 12:00 |
12:03:51.88 |
-27:39:50.9 |
HIP 58907 |
12.30 |
| 2026-07-31 00:00 |
12:03:53.20 |
-27:39:44.9 |
HIP 58907 |
12.02 |
| 2026-07-31 12:00 |
12:03:54.54 |
-27:39:39.1 |
HIP 58907 |
11.73 |
| 2026-08-01 00:00 |
12:03:55.90 |
-27:39:33.4 |
HIP 58907 |
11.44 |
| 2026-08-01 12:00 |
12:03:57.27 |
-27:39:27.9 |
HIP 58907 |
11.15 |
| 2026-08-02 00:00 |
12:03:58.66 |
-27:39:22.6 |
HIP 58907 |
10.85 |
| 2026-08-02 12:00 |
12:04:00.07 |
-27:39:17.4 |
HIP 58907 |
10.56 |
| 2026-08-03 00:00 |
12:04:01.49 |
-27:39:12.4 |
HIP 58907 |
10.26 |
| 2026-08-03 12:00 |
12:04:02.92 |
-27:39:07.6 |
HIP 58907 |
9.96 |
| 2026-08-04 00:00 |
12:04:04.37 |
-27:39:02.9 |
HIP 58907 |
9.65 |
| 2026-08-04 12:00 |
12:04:05.84 |
-27:38:58.4 |
HIP 58907 |
9.35 |
| 2026-08-05 00:00 |
12:04:07.31 |
-27:38:54.1 |
HIP 58907 |
9.04 |
| 2026-08-05 12:00 |
12:04:08.81 |
-27:38:49.9 |
HIP 58907 |
8.73 |
| 2026-08-06 00:00 |
12:04:10.32 |
-27:38:45.9 |
HIP 58907 |
8.42 |
| 2026-08-06 12:00 |
12:04:11.84 |
-27:38:42.1 |
HIP 58907 |
8.11 |
| 2026-08-07 00:00 |
12:04:13.38 |
-27:38:38.5 |
HIP 58907 |
7.79 |
| 2026-08-07 12:00 |
12:04:14.93 |
-27:38:35.0 |
HIP 58907 |
7.48 |
| 2026-08-08 00:00 |
12:04:16.50 |
-27:38:31.6 |
HIP 58907 |
7.16 |
| 2026-08-08 12:00 |
12:04:18.08 |
-27:38:28.5 |
HIP 58907 |
6.85 |
| 2026-08-09 00:00 |
12:04:19.68 |
-27:38:25.5 |
HIP 58907 |
6.53 |
| 2026-08-09 12:00 |
12:04:21.29 |
-27:38:22.7 |
HIP 58907 |
6.22 |
| 2026-08-10 00:00 |
12:04:22.91 |
-27:38:20.0 |
HIP 58907 |
5.90 |
| 2026-08-10 12:00 |
12:04:24.55 |
-27:38:17.5 |
HIP 58907 |
5.59 |
| 2026-08-11 00:00 |
12:04:26.20 |
-27:38:15.2 |
HIP 58907 |
5.28 |
| 2026-08-11 12:00 |
12:04:27.86 |
-27:38:13.1 |
HIP 58907 |
4.98 |
| 2026-08-12 00:00 |
12:04:29.54 |
-27:38:11.1 |
HIP 58907 |
4.68 |
| 2026-08-12 12:00 |
12:04:31.23 |
-27:38:09.3 |
HIP 58907 |
4.39 |
| 2026-08-13 00:00 |
12:04:32.94 |
-27:38:07.7 |
HIP 58907 |
4.10 |
| 2026-08-13 12:00 |
12:04:34.65 |
-27:38:06.2 |
HIP 58907 |
3.83 |
| 2026-08-14 00:00 |
12:04:36.38 |
-27:38:04.9 |
HIP 58907 |
3.58 |
| 2026-08-14 12:00 |
12:04:38.13 |
-27:38:03.8 |
HIP 58907 |
3.34 |
| 2026-08-15 00:00 |
12:04:39.88 |
-27:38:02.9 |
HIP 58907 |
3.13 |
| 2026-08-15 12:00 |
12:04:41.65 |
-27:38:02.1 |
HIP 58907 |
2.96 |
| 2026-08-16 00:00 |
12:04:43.43 |
-27:38:01.5 |
HIP 58907 |
2.82 |
| 2026-08-16 12:00 |
12:04:45.22 |
-27:38:01.0 |
HIP 58907 |
2.74 |
| 2026-08-17 00:00 |
12:04:47.02 |
-27:38:00.7 |
HIP 58907 |
2.70 |
| 2026-08-17 12:00 |
12:04:48.84 |
-27:38:00.6 |
HIP 58907 |
2.72 |
| 2026-08-18 00:00 |
12:04:50.67 |
-27:38:00.7 |
HIP 58907 |
2.80 |
| 2026-08-18 12:00 |
12:04:52.51 |
-27:38:00.9 |
HIP 58907 |
2.93 |
| 2026-08-19 00:00 |
12:04:54.36 |
-27:38:01.3 |
HIP 58907 |
3.11 |