| Parameter |
Value |
| Designation |
P/2025 D4 (ATLAS) |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2025-02-14T06:47:27.813120Z |
| Orbit solution date (soln_date, UTC) |
2025-09-09T12:42:49Z |
| Obs used |
313 |
| NEO |
- |
| M1 |
5.800 |
| K1 |
20.750 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2025-02-24T07:24:27.360000Z |
| Discovery magnitude (MPC) |
18.97 o |
| Discovery observatory (MPC) |
W68 · ATLAS Chile, Rio Hurtado |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2025-04-07.0000000 |
| e |
0.63433709 |
| q (au) |
3.254936 |
| a (au) |
8.901466 |
| i (deg) |
15.940781 |
| Ω (om, deg) |
233.119870 |
| ω (w, deg) |
332.889196 |
| M (ma, deg) |
1.919311 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.704 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.704 |
| n |
6.000 |
| gf |
0.950 |
| gb |
-0.645 |
| k |
0.800 |
| δ90 |
9.464 |
| 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 |
18:53:19.18 |
-06:30:03.8 |
HIP 92517 |
31.65 |
| 2026-07-29 12:00 |
18:53:06.58 |
-06:30:38.0 |
HIP 92517 |
28.84 |
| 2026-07-30 00:00 |
18:52:54.10 |
-06:31:12.9 |
HIP 92517 |
26.15 |
| 2026-07-30 12:00 |
18:52:41.76 |
-06:31:48.6 |
HIP 92517 |
23.61 |
| 2026-07-31 00:00 |
18:52:29.55 |
-06:32:24.9 |
HIP 92517 |
21.26 |
| 2026-07-31 12:00 |
18:52:17.47 |
-06:33:01.8 |
HIP 92517 |
19.15 |
| 2026-08-01 00:00 |
18:52:05.53 |
-06:33:39.4 |
HIP 92517 |
17.37 |
| 2026-08-01 12:00 |
18:51:53.73 |
-06:34:17.7 |
HIP 92517 |
15.99 |
| 2026-08-02 00:00 |
18:51:42.07 |
-06:34:56.6 |
HIP 92517 |
15.12 |
| 2026-08-02 12:00 |
18:51:30.55 |
-06:35:36.2 |
HIP 92517 |
14.81 |
| 2026-08-03 00:00 |
18:51:19.17 |
-06:36:16.3 |
HIP 92517 |
15.10 |
| 2026-08-03 12:00 |
18:51:07.94 |
-06:36:57.1 |
HIP 92517 |
15.92 |
| 2026-08-04 00:00 |
18:50:56.86 |
-06:37:38.5 |
HIP 92517 |
17.19 |
| 2026-08-04 12:00 |
18:50:45.92 |
-06:38:20.5 |
HIP 92422 |
16.68 |
| 2026-08-05 00:00 |
18:50:35.14 |
-06:39:03.0 |
HIP 92422 |
15.84 |
| 2026-08-05 12:00 |
18:50:24.50 |
-06:39:46.2 |
HIP 92422 |
15.48 |
| 2026-08-06 00:00 |
18:50:14.02 |
-06:40:29.9 |
HIP 92422 |
15.62 |
| 2026-08-06 12:00 |
18:50:03.69 |
-06:41:14.2 |
HIP 92422 |
16.22 |
| 2026-08-07 00:00 |
18:49:53.52 |
-06:41:59.0 |
HIP 92422 |
17.22 |
| 2026-08-07 12:00 |
18:49:43.50 |
-06:42:44.3 |
HIP 92422 |
18.54 |
| 2026-08-08 00:00 |
18:49:33.65 |
-06:43:30.2 |
HIP 92422 |
20.10 |
| 2026-08-08 12:00 |
18:49:23.95 |
-06:44:16.6 |
HIP 92289 |
20.60 |
| 2026-08-09 00:00 |
18:49:14.42 |
-06:45:03.5 |
HIP 92289 |
19.93 |
| 2026-08-09 12:00 |
18:49:05.05 |
-06:45:50.9 |
HIP 92289 |
19.57 |
| 2026-08-10 00:00 |
18:48:55.85 |
-06:46:38.8 |
HIP 92289 |
19.54 |
| 2026-08-10 12:00 |
18:48:46.81 |
-06:47:27.2 |
HIP 92289 |
19.83 |
| 2026-08-11 00:00 |
18:48:37.94 |
-06:48:16.0 |
HIP 92289 |
20.40 |
| 2026-08-11 12:00 |
18:48:29.24 |
-06:49:05.3 |
HIP 92289 |
21.22 |
| 2026-08-12 00:00 |
18:48:20.71 |
-06:49:55.0 |
HIP 92289 |
22.25 |
| 2026-08-12 12:00 |
18:48:12.36 |
-06:50:45.2 |
HIP 92289 |
23.46 |
| 2026-08-13 00:00 |
18:48:04.17 |
-06:51:35.8 |
HIP 92289 |
24.80 |
| 2026-08-13 12:00 |
18:47:56.16 |
-06:52:26.8 |
HIP 92289 |
26.25 |
| 2026-08-14 00:00 |
18:47:48.33 |
-06:53:18.2 |
HIP 92289 |
27.78 |
| 2026-08-14 12:00 |
18:47:40.67 |
-06:54:10.0 |
HIP 92289 |
29.37 |
| 2026-08-15 00:00 |
18:47:33.18 |
-06:55:02.1 |
HIP 92289 |
31.01 |
| 2026-08-15 12:00 |
18:47:25.88 |
-06:55:54.6 |
HIP 92289 |
32.67 |
| 2026-08-16 00:00 |
18:47:18.76 |
-06:56:47.5 |
HIP 92289 |
34.35 |
| 2026-08-16 12:00 |
18:47:11.81 |
-06:57:40.7 |
HIP 92289 |
36.05 |
| 2026-08-17 00:00 |
18:47:05.05 |
-06:58:34.3 |
HIP 92150 |
36.27 |
| 2026-08-17 12:00 |
18:46:58.47 |
-06:59:28.2 |
HIP 92150 |
35.29 |
| 2026-08-18 00:00 |
18:46:52.07 |
-07:00:22.4 |
HIP 92150 |
34.38 |
| 2026-08-18 12:00 |
18:46:45.85 |
-07:01:16.8 |
HIP 91946 |
33.31 |
| 2026-08-19 00:00 |
18:46:39.82 |
-07:02:11.6 |
HIP 91946 |
31.69 |