| Parameter |
Value |
| Designation |
C/2025 W2 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2025-12-07T20:01:40.048320Z |
| Orbit solution date (soln_date, UTC) |
2026-01-07T15:42:51Z |
| Obs used |
54 |
| NEO |
- |
| M1 |
15.400 |
| K1 |
23.250 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2025-11-28T14:38:51.734400Z |
| Discovery magnitude (MPC) |
19.16 o |
| Discovery observatory (MPC) |
T08 · ATLAS-MLO, Mauna Loa |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2025-12-01.0000000 |
| e |
0.94608895 |
| q (au) |
1.453281 |
| a (au) |
26.957020 |
| i (deg) |
94.710549 |
| Ω (om, deg) |
90.844949 |
| ω (w, deg) |
41.034555 |
| M (ma, deg) |
359.951871 |
Magnitude
Scatter + Global Linear
$$
M_a = (16.538 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
16.538 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.948 |
| 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 |
20:51:11.17 |
+42:42:36.3 |
HIP 102788 |
19.29 |
| 2026-03-26 12:00 |
20:51:07.24 |
+42:44:55.6 |
HIP 102788 |
19.25 |
| 2026-03-27 00:00 |
20:51:02.90 |
+42:47:17.0 |
HIP 102788 |
19.46 |
| 2026-03-27 12:00 |
20:50:58.14 |
+42:49:40.4 |
HIP 102788 |
19.94 |
| 2026-03-28 00:00 |
20:50:52.95 |
+42:52:05.8 |
HIP 102746 |
20.01 |
| 2026-03-28 12:00 |
20:50:47.33 |
+42:54:33.1 |
HIP 102746 |
18.49 |
| 2026-03-29 00:00 |
20:50:41.29 |
+42:57:02.3 |
HIP 102746 |
17.18 |
| 2026-03-29 12:00 |
20:50:34.81 |
+42:59:33.3 |
HIP 102746 |
16.15 |
| 2026-03-30 00:00 |
20:50:27.89 |
+43:02:06.2 |
HIP 102746 |
15.48 |
| 2026-03-30 12:00 |
20:50:20.54 |
+43:04:40.8 |
HIP 102746 |
15.27 |
| 2026-03-31 00:00 |
20:50:12.74 |
+43:07:17.2 |
HIP 102746 |
15.57 |
| 2026-03-31 12:00 |
20:50:04.49 |
+43:09:55.2 |
HIP 102746 |
16.37 |
| 2026-04-01 00:00 |
20:49:55.80 |
+43:12:35.0 |
HIP 102746 |
17.66 |
| 2026-04-01 12:00 |
20:49:46.66 |
+43:15:16.3 |
HIP 102746 |
19.35 |
| 2026-04-02 00:00 |
20:49:37.06 |
+43:17:59.3 |
HIP 102622 |
20.77 |
| 2026-04-02 12:00 |
20:49:27.00 |
+43:20:43.8 |
HIP 102622 |
19.40 |
| 2026-04-03 00:00 |
20:49:16.48 |
+43:23:29.8 |
HIP 102622 |
18.44 |
| 2026-04-03 12:00 |
20:49:05.50 |
+43:26:17.3 |
HIP 102622 |
18.02 |
| 2026-04-04 00:00 |
20:48:54.04 |
+43:29:06.2 |
HIP 102622 |
18.21 |
| 2026-04-04 12:00 |
20:48:42.11 |
+43:31:56.6 |
HIP 102794 |
16.99 |
| 2026-04-05 00:00 |
20:48:29.71 |
+43:34:48.2 |
HIP 102794 |
16.11 |
| 2026-04-05 12:00 |
20:48:16.82 |
+43:37:41.2 |
HIP 102794 |
16.09 |
| 2026-04-06 00:00 |
20:48:03.46 |
+43:40:35.5 |
HIP 102794 |
16.97 |
| 2026-04-06 12:00 |
20:47:49.60 |
+43:43:31.0 |
HIP 102794 |
18.67 |
| 2026-04-07 00:00 |
20:47:35.25 |
+43:46:27.7 |
HIP 102667 |
19.58 |
| 2026-04-07 12:00 |
20:47:20.41 |
+43:49:25.5 |
HIP 102667 |
18.21 |
| 2026-04-08 00:00 |
20:47:05.06 |
+43:52:24.4 |
HIP 102667 |
17.69 |
| 2026-04-08 12:00 |
20:46:49.21 |
+43:55:24.4 |
HIP 102667 |
18.16 |
| 2026-04-09 00:00 |
20:46:32.86 |
+43:58:25.3 |
HIP 102667 |
19.60 |
| 2026-04-09 12:00 |
20:46:15.99 |
+44:01:27.3 |
HIP 102359 |
20.79 |
| 2026-04-10 00:00 |
20:45:58.60 |
+44:04:30.1 |
HIP 102359 |
18.63 |
| 2026-04-10 12:00 |
20:45:40.70 |
+44:07:33.8 |
HIP 102359 |
17.25 |
| 2026-04-11 00:00 |
20:45:22.27 |
+44:10:38.3 |
HIP 102359 |
16.92 |
| 2026-04-11 12:00 |
20:45:03.31 |
+44:13:43.6 |
HIP 102401 |
16.18 |
| 2026-04-12 00:00 |
20:44:43.82 |
+44:16:49.5 |
HIP 102401 |
13.55 |
| 2026-04-12 12:00 |
20:44:23.79 |
+44:19:56.1 |
HIP 102401 |
12.26 |
| 2026-04-13 00:00 |
20:44:03.23 |
+44:23:03.4 |
HIP 102401 |
12.79 |
| 2026-04-13 12:00 |
20:43:42.11 |
+44:26:11.1 |
HIP 102401 |
15.03 |
| 2026-04-14 00:00 |
20:43:20.44 |
+44:29:19.4 |
HIP 102401 |
18.43 |
| 2026-04-14 12:00 |
20:42:58.23 |
+44:32:28.0 |
HIP 102074 |
22.47 |
| 2026-04-15 00:00 |
20:42:35.45 |
+44:35:37.1 |
HIP 102074 |
21.00 |
| 2026-04-15 12:00 |
20:42:12.11 |
+44:38:46.4 |
HIP 102074 |
20.70 |
| 2026-04-16 00:00 |
20:41:48.20 |
+44:41:56.0 |
HIP 102074 |
21.66 |