| Parameter |
Value |
| Designation |
C/2022 U2 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2023-01-14T05:16:42.461760Z |
| Orbit solution date (soln_date, UTC) |
2023-11-04T19:42:53Z |
| Obs used |
996 |
| NEO |
- |
| M1 |
13.600 |
| K1 |
19.750 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2022-10-25T05:05:57.926400Z |
| Discovery magnitude (MPC) |
19.13 o |
| Discovery observatory (MPC) |
T08 · ATLAS-MLO, Mauna Loa |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2023-01-07.0000000 |
| e |
0.98612019 |
| q (au) |
1.328023 |
| a (au) |
95.680211 |
| i (deg) |
48.249781 |
| Ω (om, deg) |
304.475901 |
| ω (w, deg) |
147.908535 |
| M (ma, deg) |
359.992397 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.410 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.410 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.998 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2022-10-25 |
2022-11-25 |
+10.6742 |
-2.041 |
| 2022-11-25 |
2023-01-13 |
+45.3999 |
-7.789 |
| 2023-01-14 |
2023-05-19 |
+3.5650 |
-2.032 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
14:07:58.68 |
-62:50:59.7 |
HIP 69080 |
2.98 |
| 2026-07-29 12:00 |
14:08:03.15 |
-62:49:09.7 |
HIP 69080 |
3.54 |
| 2026-07-30 00:00 |
14:08:07.79 |
-62:47:20.3 |
HIP 69080 |
4.83 |
| 2026-07-30 12:00 |
14:08:12.58 |
-62:45:31.3 |
HIP 69080 |
6.42 |
| 2026-07-31 00:00 |
14:08:17.53 |
-62:43:42.8 |
HIP 69080 |
8.13 |
| 2026-07-31 12:00 |
14:08:22.64 |
-62:41:54.8 |
HIP 69080 |
9.90 |
| 2026-08-01 00:00 |
14:08:27.91 |
-62:40:07.2 |
HIP 69080 |
11.70 |
| 2026-08-01 12:00 |
14:08:33.34 |
-62:38:20.2 |
HIP 69080 |
13.52 |
| 2026-08-02 00:00 |
14:08:38.92 |
-62:36:33.7 |
HIP 69080 |
15.34 |
| 2026-08-02 12:00 |
14:08:44.65 |
-62:34:47.6 |
HIP 69261 |
15.03 |
| 2026-08-03 00:00 |
14:08:50.54 |
-62:33:02.1 |
HIP 69261 |
13.77 |
| 2026-08-03 12:00 |
14:08:56.58 |
-62:31:17.2 |
HIP 69216 |
12.45 |
| 2026-08-04 00:00 |
14:09:02.78 |
-62:29:32.7 |
HIP 69216 |
10.75 |
| 2026-08-04 12:00 |
14:09:09.13 |
-62:27:48.8 |
HIP 69216 |
9.13 |
| 2026-08-05 00:00 |
14:09:15.62 |
-62:26:05.4 |
HIP 69216 |
7.61 |
| 2026-08-05 12:00 |
14:09:22.27 |
-62:24:22.5 |
HIP 69216 |
6.27 |
| 2026-08-06 00:00 |
14:09:29.07 |
-62:22:40.2 |
HIP 69216 |
5.25 |
| 2026-08-06 12:00 |
14:09:36.01 |
-62:20:58.5 |
HIP 69216 |
4.76 |
| 2026-08-07 00:00 |
14:09:43.11 |
-62:19:17.3 |
HIP 69216 |
4.97 |
| 2026-08-07 12:00 |
14:09:50.35 |
-62:17:36.7 |
HIP 69216 |
5.79 |
| 2026-08-08 00:00 |
14:09:57.74 |
-62:15:56.7 |
HIP 69216 |
7.01 |
| 2026-08-08 12:00 |
14:10:05.27 |
-62:14:17.2 |
HIP 69216 |
8.46 |
| 2026-08-09 00:00 |
14:10:12.95 |
-62:12:38.3 |
HIP 69216 |
10.05 |
| 2026-08-09 12:00 |
14:10:20.77 |
-62:11:00.0 |
HIP 69216 |
11.71 |
| 2026-08-10 00:00 |
14:10:28.73 |
-62:09:22.3 |
HIP 69358 |
12.11 |
| 2026-08-10 12:00 |
14:10:36.84 |
-62:07:45.2 |
HIP 69358 |
10.37 |
| 2026-08-11 00:00 |
14:10:45.08 |
-62:06:08.7 |
HIP 69358 |
8.67 |
| 2026-08-11 12:00 |
14:10:53.47 |
-62:04:32.8 |
HIP 69358 |
7.04 |
| 2026-08-12 00:00 |
14:11:02.00 |
-62:02:57.6 |
HIP 69358 |
5.57 |
| 2026-08-12 12:00 |
14:11:10.67 |
-62:01:22.9 |
HIP 69358 |
4.38 |
| 2026-08-13 00:00 |
14:11:19.47 |
-61:59:48.9 |
HIP 69358 |
3.78 |
| 2026-08-13 12:00 |
14:11:28.41 |
-61:58:15.5 |
HIP 69358 |
4.04 |
| 2026-08-14 00:00 |
14:11:37.49 |
-61:56:42.7 |
HIP 69358 |
5.02 |
| 2026-08-14 12:00 |
14:11:46.70 |
-61:55:10.6 |
HIP 69358 |
6.41 |
| 2026-08-15 00:00 |
14:11:56.05 |
-61:53:39.1 |
HIP 69358 |
7.98 |
| 2026-08-15 12:00 |
14:12:05.52 |
-61:52:08.3 |
HIP 69358 |
9.66 |
| 2026-08-16 00:00 |
14:12:15.13 |
-61:50:38.1 |
HIP 69358 |
11.40 |
| 2026-08-16 12:00 |
14:12:24.88 |
-61:49:08.6 |
HIP 69358 |
13.17 |
| 2026-08-17 00:00 |
14:12:34.75 |
-61:47:39.7 |
HIP 69578 |
13.71 |
| 2026-08-17 12:00 |
14:12:44.75 |
-61:46:11.5 |
HIP 69578 |
12.65 |
| 2026-08-18 00:00 |
14:12:54.88 |
-61:44:44.0 |
HIP 69578 |
11.79 |
| 2026-08-18 12:00 |
14:13:05.13 |
-61:43:17.1 |
HIP 69578 |
11.16 |
| 2026-08-19 00:00 |
14:13:15.51 |
-61:41:50.9 |
HIP 69578 |
10.80 |