| 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) |
| 2026-03-26 00:00 |
05:53:07.96 |
-34:57:31.3 |
HIP 27925 |
18.93 |
| 2026-03-26 12:00 |
05:53:08.39 |
-34:55:57.0 |
HIP 27925 |
19.53 |
| 2026-03-27 00:00 |
05:53:08.90 |
-34:54:22.9 |
HIP 27925 |
20.23 |
| 2026-03-27 12:00 |
05:53:09.46 |
-34:52:49.0 |
HIP 27788 |
19.64 |
| 2026-03-28 00:00 |
05:53:10.10 |
-34:51:15.3 |
HIP 27788 |
18.14 |
| 2026-03-28 12:00 |
05:53:10.80 |
-34:49:41.7 |
HIP 27788 |
16.67 |
| 2026-03-29 00:00 |
05:53:11.56 |
-34:48:08.3 |
HIP 27788 |
15.22 |
| 2026-03-29 12:00 |
05:53:12.39 |
-34:46:35.1 |
HIP 27788 |
13.81 |
| 2026-03-30 00:00 |
05:53:13.29 |
-34:45:02.1 |
HIP 27788 |
12.44 |
| 2026-03-30 12:00 |
05:53:14.25 |
-34:43:29.2 |
HIP 27788 |
11.13 |
| 2026-03-31 00:00 |
05:53:15.28 |
-34:41:56.6 |
HIP 27788 |
9.90 |
| 2026-03-31 12:00 |
05:53:16.37 |
-34:40:24.2 |
HIP 27788 |
8.78 |
| 2026-04-01 00:00 |
05:53:17.52 |
-34:38:52.0 |
HIP 27788 |
7.84 |
| 2026-04-01 12:00 |
05:53:18.74 |
-34:37:20.1 |
HIP 27788 |
7.12 |
| 2026-04-02 00:00 |
05:53:20.02 |
-34:35:48.3 |
HIP 27788 |
6.71 |
| 2026-04-02 12:00 |
05:53:21.37 |
-34:34:16.8 |
HIP 27788 |
6.66 |
| 2026-04-03 00:00 |
05:53:22.78 |
-34:32:45.5 |
HIP 27788 |
6.97 |
| 2026-04-03 12:00 |
05:53:24.25 |
-34:31:14.4 |
HIP 27788 |
7.60 |
| 2026-04-04 00:00 |
05:53:25.78 |
-34:29:43.6 |
HIP 27788 |
8.49 |
| 2026-04-04 12:00 |
05:53:27.38 |
-34:28:13.0 |
HIP 27788 |
9.55 |
| 2026-04-05 00:00 |
05:53:29.03 |
-34:26:42.7 |
HIP 27788 |
10.73 |
| 2026-04-05 12:00 |
05:53:30.75 |
-34:25:12.6 |
HIP 27788 |
12.01 |
| 2026-04-06 00:00 |
05:53:32.53 |
-34:23:42.8 |
HIP 27788 |
13.34 |
| 2026-04-06 12:00 |
05:53:34.37 |
-34:22:13.3 |
HIP 27788 |
14.72 |
| 2026-04-07 00:00 |
05:53:36.28 |
-34:20:44.0 |
HIP 27788 |
16.14 |
| 2026-04-07 12:00 |
05:53:38.24 |
-34:19:15.1 |
HIP 27788 |
17.58 |
| 2026-04-08 00:00 |
05:53:40.26 |
-34:17:46.4 |
HIP 27788 |
19.03 |
| 2026-04-08 12:00 |
05:53:42.35 |
-34:16:17.9 |
HIP 27788 |
20.51 |
| 2026-04-09 00:00 |
05:53:44.49 |
-34:14:49.8 |
HIP 27788 |
21.99 |
| 2026-04-09 12:00 |
05:53:46.69 |
-34:13:22.0 |
HIP 27788 |
23.48 |
| 2026-04-10 00:00 |
05:53:48.95 |
-34:11:54.4 |
HIP 27788 |
24.98 |
| 2026-04-10 12:00 |
05:53:51.27 |
-34:10:27.2 |
HIP 27810 |
24.19 |
| 2026-04-11 00:00 |
05:53:53.65 |
-34:09:00.3 |
HIP 27810 |
23.06 |
| 2026-04-11 12:00 |
05:53:56.09 |
-34:07:33.7 |
HIP 27810 |
21.99 |
| 2026-04-12 00:00 |
05:53:58.58 |
-34:06:07.4 |
HIP 27810 |
20.98 |
| 2026-04-12 12:00 |
05:54:01.14 |
-34:04:41.5 |
HIP 27810 |
20.06 |
| 2026-04-13 00:00 |
05:54:03.75 |
-34:03:15.8 |
HIP 27810 |
19.22 |
| 2026-04-13 12:00 |
05:54:06.41 |
-34:01:50.5 |
HIP 27810 |
18.49 |
| 2026-04-14 00:00 |
05:54:09.14 |
-34:00:25.6 |
HIP 27810 |
17.86 |
| 2026-04-14 12:00 |
05:54:11.92 |
-33:59:01.0 |
HIP 27810 |
17.37 |
| 2026-04-15 00:00 |
05:54:14.75 |
-33:57:36.7 |
HIP 27810 |
17.00 |
| 2026-04-15 12:00 |
05:54:17.64 |
-33:56:12.8 |
HIP 27810 |
16.79 |
| 2026-04-16 00:00 |
05:54:20.59 |
-33:54:49.3 |
HIP 27967 |
16.70 |