| 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
$$
M_a = (10.708 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.708 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.645 |
| k |
0.800 |
| δ90 |
9.994 |
| 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 |
19:12:53.54 |
-11:45:45.7 |
HIP 94390 |
12.96 |
| 2026-03-26 12:00 |
19:13:11.03 |
-11:43:26.7 |
HIP 94390 |
12.37 |
| 2026-03-27 00:00 |
19:13:28.33 |
-11:41:07.6 |
HIP 94390 |
13.58 |
| 2026-03-27 12:00 |
19:13:45.45 |
-11:38:48.5 |
HIP 94390 |
16.16 |
| 2026-03-28 00:00 |
19:14:02.37 |
-11:36:29.2 |
HIP 94390 |
19.54 |
| 2026-03-28 12:00 |
19:14:19.11 |
-11:34:09.9 |
HIP 94633 |
18.54 |
| 2026-03-29 00:00 |
19:14:35.65 |
-11:31:50.5 |
HIP 94633 |
16.54 |
| 2026-03-29 12:00 |
19:14:52.00 |
-11:29:31.0 |
HIP 94633 |
15.74 |
| 2026-03-30 00:00 |
19:15:08.16 |
-11:27:11.5 |
HIP 94633 |
16.29 |
| 2026-03-30 12:00 |
19:15:24.12 |
-11:24:51.9 |
HIP 94633 |
18.03 |
| 2026-03-31 00:00 |
19:15:39.89 |
-11:22:32.3 |
HIP 94722 |
16.42 |
| 2026-03-31 12:00 |
19:15:55.47 |
-11:20:12.7 |
HIP 94722 |
15.95 |
| 2026-04-01 00:00 |
19:16:10.85 |
-11:17:53.1 |
HIP 94722 |
16.73 |
| 2026-04-01 12:00 |
19:16:26.04 |
-11:15:33.4 |
HIP 94757 |
18.40 |
| 2026-04-02 00:00 |
19:16:41.03 |
-11:13:13.7 |
HIP 94757 |
15.17 |
| 2026-04-02 12:00 |
19:16:55.82 |
-11:10:54.0 |
HIP 94757 |
12.62 |
| 2026-04-03 00:00 |
19:17:10.42 |
-11:08:34.3 |
HIP 94757 |
11.20 |
| 2026-04-03 12:00 |
19:17:24.82 |
-11:06:14.6 |
HIP 94757 |
11.28 |
| 2026-04-04 00:00 |
19:17:39.02 |
-11:03:54.9 |
HIP 94757 |
12.80 |
| 2026-04-04 12:00 |
19:17:53.02 |
-11:01:35.2 |
HIP 94757 |
15.30 |
| 2026-04-05 00:00 |
19:18:06.82 |
-10:59:15.6 |
HIP 94925 |
13.29 |
| 2026-04-05 12:00 |
19:18:20.42 |
-10:56:56.0 |
HIP 94925 |
9.56 |
| 2026-04-06 00:00 |
19:18:33.81 |
-10:54:36.5 |
HIP 94925 |
6.32 |
| 2026-04-06 12:00 |
19:18:47.01 |
-10:52:17.0 |
HIP 94925 |
4.60 |
| 2026-04-07 00:00 |
19:19:00.00 |
-10:49:57.5 |
HIP 94925 |
5.84 |
| 2026-04-07 12:00 |
19:19:12.79 |
-10:47:38.1 |
HIP 94925 |
8.82 |
| 2026-04-08 00:00 |
19:19:25.37 |
-10:45:18.8 |
HIP 94925 |
12.31 |
| 2026-04-08 12:00 |
19:19:37.75 |
-10:42:59.6 |
HIP 95049 |
14.86 |
| 2026-04-09 00:00 |
19:19:49.93 |
-10:40:40.5 |
HIP 95049 |
11.07 |
| 2026-04-09 12:00 |
19:20:01.89 |
-10:38:21.4 |
HIP 95049 |
7.33 |
| 2026-04-10 00:00 |
19:20:13.66 |
-10:36:02.5 |
HIP 95049 |
3.63 |
| 2026-04-10 12:00 |
19:20:25.21 |
-10:33:43.6 |
HIP 95049 |
0.17 |
| 2026-04-11 00:00 |
19:20:36.55 |
-10:31:24.9 |
HIP 95049 |
3.66 |
| 2026-04-11 12:00 |
19:20:47.69 |
-10:29:06.3 |
HIP 95049 |
7.24 |
| 2026-04-12 00:00 |
19:20:58.61 |
-10:26:47.9 |
HIP 95049 |
10.78 |
| 2026-04-12 12:00 |
19:21:09.33 |
-10:24:29.6 |
HIP 95049 |
14.28 |
| 2026-04-13 00:00 |
19:21:19.84 |
-10:22:11.4 |
HIP 95138 |
11.64 |
| 2026-04-13 12:00 |
19:21:30.13 |
-10:19:53.5 |
HIP 95138 |
9.53 |
| 2026-04-14 00:00 |
19:21:40.21 |
-10:17:35.6 |
HIP 95138 |
8.31 |
| 2026-04-14 12:00 |
19:21:50.08 |
-10:15:18.0 |
HIP 95138 |
8.34 |
| 2026-04-15 00:00 |
19:21:59.73 |
-10:13:00.6 |
HIP 95138 |
9.56 |
| 2026-04-15 12:00 |
19:22:09.18 |
-10:10:43.3 |
HIP 95138 |
11.57 |
| 2026-04-16 00:00 |
19:22:18.40 |
-10:08:26.3 |
HIP 95138 |
14.00 |