C/2025 W2 (ATLAS)
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
20:26:39.63 |
+43:44:44.6 |
HIP 100749 |
12.16 |
| 2026-02-03 12:00 |
20:27:11.85 |
+43:39:53.2 |
HIP 100989 |
16.62 |
| 2026-02-04 00:00 |
20:27:43.63 |
+43:35:08.9 |
HIP 100989 |
9.33 |
| 2026-02-04 12:00 |
20:28:15.00 |
+43:30:31.8 |
HIP 100989 |
2.98 |
| 2026-02-05 00:00 |
20:28:45.95 |
+43:26:01.7 |
HIP 100989 |
6.03 |
| 2026-02-05 12:00 |
20:29:16.49 |
+43:21:38.6 |
HIP 100989 |
12.81 |
| 2026-02-06 00:00 |
20:29:46.63 |
+43:17:22.3 |
HIP 101179 |
13.23 |
| 2026-02-06 12:00 |
20:30:16.37 |
+43:13:12.9 |
HIP 101179 |
14.85 |
| 2026-02-07 00:00 |
20:30:45.71 |
+43:09:10.1 |
HIP 101323 |
16.74 |
| 2026-02-07 12:00 |
20:31:14.66 |
+43:05:13.9 |
HIP 101323 |
10.70 |
| 2026-02-08 00:00 |
20:31:43.23 |
+43:01:24.3 |
HIP 101323 |
5.99 |
| 2026-02-08 12:00 |
20:32:11.42 |
+42:57:41.2 |
HIP 101323 |
6.28 |
| 2026-02-09 00:00 |
20:32:39.23 |
+42:54:04.4 |
HIP 101323 |
11.00 |
| 2026-02-09 12:00 |
20:33:06.67 |
+42:50:33.9 |
HIP 101323 |
16.62 |
| 2026-02-10 00:00 |
20:33:33.74 |
+42:47:09.7 |
HIP 101323 |
22.39 |
| 2026-02-10 12:00 |
20:34:00.44 |
+42:43:51.7 |
HIP 101323 |
28.14 |
| 2026-02-11 00:00 |
20:34:26.78 |
+42:40:39.7 |
HIP 101323 |
33.83 |
| 2026-02-11 12:00 |
20:34:52.76 |
+42:37:33.7 |
HIP 101763 |
29.22 |
| 2026-02-12 00:00 |
20:35:18.38 |
+42:34:33.7 |
HIP 101763 |
24.23 |
| 2026-02-12 12:00 |
20:35:43.65 |
+42:31:39.5 |
HIP 101763 |
19.61 |
| 2026-02-13 00:00 |
20:36:08.57 |
+42:28:51.2 |
HIP 101763 |
15.60 |
| 2026-02-13 12:00 |
20:36:33.13 |
+42:26:08.6 |
HIP 101763 |
12.63 |
| 2026-02-14 00:00 |
20:36:57.35 |
+42:23:31.6 |
HIP 101763 |
11.42 |
| 2026-02-14 12:00 |
20:37:21.23 |
+42:21:00.3 |
HIP 101763 |
12.36 |
| 2026-02-15 00:00 |
20:37:44.76 |
+42:18:34.5 |
HIP 101832 |
9.47 |
| 2026-02-15 12:00 |
20:38:07.95 |
+42:16:14.2 |
HIP 101832 |
5.83 |
| 2026-02-16 00:00 |
20:38:30.80 |
+42:13:59.3 |
HIP 101832 |
5.12 |
| 2026-02-16 12:00 |
20:38:53.31 |
+42:11:49.7 |
HIP 101832 |
7.98 |
| 2026-02-17 00:00 |
20:39:15.49 |
+42:09:45.5 |
HIP 101948 |
6.12 |
| 2026-02-17 12:00 |
20:39:37.33 |
+42:07:46.4 |
HIP 101948 |
7.22 |
| 2026-02-18 00:00 |
20:39:58.83 |
+42:05:52.5 |
HIP 101948 |
10.25 |
| 2026-02-18 12:00 |
20:40:20.01 |
+42:04:03.8 |
HIP 101948 |
13.94 |
| 2026-02-19 00:00 |
20:40:40.85 |
+42:02:20.0 |
HIP 101948 |
17.81 |
| 2026-02-19 12:00 |
20:41:01.35 |
+42:00:41.2 |
HIP 102155 |
20.44 |
| 2026-02-20 00:00 |
20:41:21.53 |
+41:59:07.4 |
HIP 102155 |
17.38 |
| 2026-02-20 12:00 |
20:41:41.38 |
+41:57:38.4 |
HIP 102155 |
14.90 |
| 2026-02-21 00:00 |
20:42:00.90 |
+41:56:14.2 |
HIP 102155 |
13.25 |
| 2026-02-21 12:00 |
20:42:20.09 |
+41:54:54.8 |
HIP 102155 |
12.69 |
| 2026-02-22 00:00 |
20:42:38.96 |
+41:53:40.0 |
HIP 102155 |
13.27 |
| 2026-02-22 12:00 |
20:42:57.50 |
+41:52:29.9 |
HIP 102313 |
9.84 |
| 2026-02-23 00:00 |
20:43:15.71 |
+41:51:24.4 |
HIP 102313 |
6.31 |
| 2026-02-23 12:00 |
20:43:33.59 |
+41:50:23.3 |
HIP 102313 |
2.93 |
| 2026-02-24 00:00 |
20:43:51.15 |
+41:49:26.8 |
HIP 102313 |
1.15 |