| Parameter |
Value |
| Designation |
C/2017 M4 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-01-18T08:09:45.547200Z |
| Orbit solution date (soln_date, UTC) |
2022-07-31T01:42:28Z |
| Obs used |
3296 |
| NEO |
- |
| M1 |
9.400 |
| K1 |
6.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-06-17.0000000 |
| e |
1.00108487 |
| q (au) |
3.251701 |
| a (au) |
-2997.319774 |
| i (deg) |
105.657087 |
| Ω (om, deg) |
65.868353 |
| ω (w, deg) |
167.652626 |
| M (ma, deg) |
-0.001293 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.294 + 2.998\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.294 |
| n |
2.998 |
| gf |
0.999 |
| gb |
-1.000 |
| 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) |
| 2026-06-01 00:00 |
06:01:54.71 |
-32:20:04.1 |
HIP 28679 |
23.37 |
| 2026-06-01 12:00 |
06:02:01.03 |
-32:19:27.7 |
HIP 28679 |
21.96 |
| 2026-06-02 00:00 |
06:02:07.37 |
-32:18:52.0 |
HIP 28679 |
20.57 |
| 2026-06-02 12:00 |
06:02:13.73 |
-32:18:16.8 |
HIP 28679 |
19.20 |
| 2026-06-03 00:00 |
06:02:20.10 |
-32:17:42.3 |
HIP 28679 |
17.84 |
| 2026-06-03 12:00 |
06:02:26.48 |
-32:17:08.3 |
HIP 28679 |
16.51 |
| 2026-06-04 00:00 |
06:02:32.88 |
-32:16:34.9 |
HIP 28679 |
15.21 |
| 2026-06-04 12:00 |
06:02:39.29 |
-32:16:02.2 |
HIP 28679 |
13.95 |
| 2026-06-05 00:00 |
06:02:45.72 |
-32:15:30.0 |
HIP 28679 |
12.74 |
| 2026-06-05 12:00 |
06:02:52.16 |
-32:14:58.5 |
HIP 28679 |
11.59 |
| 2026-06-06 00:00 |
06:02:58.62 |
-32:14:27.5 |
HIP 28679 |
10.53 |
| 2026-06-06 12:00 |
06:03:05.09 |
-32:13:57.2 |
HIP 28679 |
9.59 |
| 2026-06-07 00:00 |
06:03:11.57 |
-32:13:27.4 |
HIP 28679 |
8.79 |
| 2026-06-07 12:00 |
06:03:18.06 |
-32:12:58.3 |
HIP 28679 |
8.19 |
| 2026-06-08 00:00 |
06:03:24.56 |
-32:12:29.8 |
HIP 28679 |
7.83 |
| 2026-06-08 12:00 |
06:03:31.08 |
-32:12:01.9 |
HIP 28679 |
7.74 |
| 2026-06-09 00:00 |
06:03:37.60 |
-32:11:34.6 |
HIP 28679 |
7.94 |
| 2026-06-09 12:00 |
06:03:44.14 |
-32:11:07.9 |
HIP 28756 |
7.68 |
| 2026-06-10 00:00 |
06:03:50.69 |
-32:10:41.8 |
HIP 28756 |
6.27 |
| 2026-06-10 12:00 |
06:03:57.24 |
-32:10:16.3 |
HIP 28756 |
4.88 |
| 2026-06-11 00:00 |
06:04:03.81 |
-32:09:51.5 |
HIP 28756 |
3.52 |
| 2026-06-11 12:00 |
06:04:10.38 |
-32:09:27.2 |
HIP 28756 |
2.28 |
| 2026-06-12 00:00 |
06:04:16.96 |
-32:09:03.6 |
HIP 28756 |
1.48 |
| 2026-06-12 12:00 |
06:04:23.55 |
-32:08:40.6 |
HIP 28756 |
1.82 |
| 2026-06-13 00:00 |
06:04:30.15 |
-32:08:18.2 |
HIP 28756 |
2.93 |
| 2026-06-13 12:00 |
06:04:36.75 |
-32:07:56.5 |
HIP 28756 |
4.25 |
| 2026-06-14 00:00 |
06:04:43.36 |
-32:07:35.3 |
HIP 28756 |
5.62 |
| 2026-06-14 12:00 |
06:04:49.98 |
-32:07:14.8 |
HIP 28756 |
7.02 |
| 2026-06-15 00:00 |
06:04:56.60 |
-32:06:54.9 |
HIP 28756 |
8.43 |
| 2026-06-15 12:00 |
06:05:03.23 |
-32:06:35.6 |
HIP 28756 |
9.84 |
| 2026-06-16 00:00 |
06:05:09.86 |
-32:06:16.9 |
HIP 28756 |
11.26 |
| 2026-06-16 12:00 |
06:05:16.49 |
-32:05:58.8 |
HIP 28756 |
12.68 |
| 2026-06-17 00:00 |
06:05:23.13 |
-32:05:41.4 |
HIP 28756 |
14.10 |
| 2026-06-17 12:00 |
06:05:29.77 |
-32:05:24.6 |
HIP 28756 |
15.52 |
| 2026-06-18 00:00 |
06:05:36.42 |
-32:05:08.4 |
HIP 28756 |
16.95 |
| 2026-06-18 12:00 |
06:05:43.06 |
-32:04:52.8 |
HIP 28756 |
18.37 |
| 2026-06-19 00:00 |
06:05:49.71 |
-32:04:37.8 |
HIP 28999 |
19.75 |
| 2026-06-19 12:00 |
06:05:56.36 |
-32:04:23.5 |
HIP 28999 |
18.45 |
| 2026-06-20 00:00 |
06:06:03.01 |
-32:04:09.8 |
HIP 28999 |
17.17 |
| 2026-06-20 12:00 |
06:06:09.66 |
-32:03:56.7 |
HIP 28999 |
15.93 |
| 2026-06-21 00:00 |
06:06:16.31 |
-32:03:44.2 |
HIP 28999 |
14.72 |
| 2026-06-21 12:00 |
06:06:22.96 |
-32:03:32.3 |
HIP 28999 |
13.57 |
| 2026-06-22 00:00 |
06:06:29.61 |
-32:03:21.0 |
HIP 28999 |
12.48 |