| 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) |
| 2026-09-20 00:00 |
14:28:02.62 |
-60:34:43.7 |
HIP 70808 |
6.36 |
| 2026-09-20 12:00 |
14:28:19.38 |
-60:34:05.0 |
HIP 70808 |
4.21 |
| 2026-09-21 00:00 |
14:28:36.21 |
-60:33:27.1 |
HIP 70808 |
2.08 |
| 2026-09-21 12:00 |
14:28:53.11 |
-60:32:49.9 |
HIP 70808 |
0.50 |
| 2026-09-22 00:00 |
14:29:10.08 |
-60:32:13.4 |
HIP 70808 |
2.37 |
| 2026-09-22 12:00 |
14:29:27.13 |
-60:31:37.7 |
HIP 70808 |
4.53 |
| 2026-09-23 00:00 |
14:29:44.23 |
-60:31:02.8 |
HIP 70808 |
6.70 |
| 2026-09-23 12:00 |
14:30:01.41 |
-60:30:28.6 |
HIP 70808 |
8.89 |
| 2026-09-24 00:00 |
14:30:18.65 |
-60:29:55.2 |
HIP 70808 |
11.08 |
| 2026-09-24 12:00 |
14:30:35.96 |
-60:29:22.5 |
HIP 70808 |
13.28 |
| 2026-09-25 00:00 |
14:30:53.33 |
-60:28:50.5 |
HIP 70808 |
15.49 |
| 2026-09-25 12:00 |
14:31:10.77 |
-60:28:19.3 |
HIP 70808 |
17.70 |
| 2026-09-26 00:00 |
14:31:28.27 |
-60:27:48.9 |
HIP 70808 |
19.91 |
| 2026-09-26 12:00 |
14:31:45.84 |
-60:27:19.1 |
HIP 70808 |
22.13 |
| 2026-09-27 00:00 |
14:32:03.46 |
-60:26:50.2 |
HIP 70808 |
24.36 |
| 2026-09-27 12:00 |
14:32:21.15 |
-60:26:21.9 |
HIP 70808 |
26.59 |
| 2026-09-28 00:00 |
14:32:38.90 |
-60:25:54.4 |
HIP 70808 |
28.83 |
| 2026-09-28 12:00 |
14:32:56.70 |
-60:25:27.7 |
HIP 71333 |
30.09 |
| 2026-09-29 00:00 |
14:33:14.57 |
-60:25:01.7 |
HIP 71333 |
28.49 |
| 2026-09-29 12:00 |
14:33:32.50 |
-60:24:36.4 |
HIP 71333 |
27.00 |
| 2026-09-30 00:00 |
14:33:50.48 |
-60:24:11.9 |
HIP 71333 |
25.63 |
| 2026-09-30 12:00 |
14:34:08.52 |
-60:23:48.1 |
HIP 71333 |
24.40 |
| 2026-10-01 00:00 |
14:34:26.62 |
-60:23:25.0 |
HIP 71333 |
23.34 |
| 2026-10-01 12:00 |
14:34:44.78 |
-60:23:02.7 |
HIP 71333 |
22.47 |
| 2026-10-02 00:00 |
14:35:02.99 |
-60:22:41.1 |
HIP 71333 |
21.82 |
| 2026-10-02 12:00 |
14:35:21.26 |
-60:22:20.3 |
HIP 71333 |
21.41 |
| 2026-10-03 00:00 |
14:35:39.58 |
-60:22:00.2 |
HIP 71333 |
21.25 |
| 2026-10-03 12:00 |
14:35:57.95 |
-60:21:40.8 |
HIP 71333 |
21.36 |
| 2026-10-04 00:00 |
14:36:16.38 |
-60:21:22.2 |
HIP 71333 |
21.72 |
| 2026-10-04 12:00 |
14:36:34.86 |
-60:21:04.3 |
HIP 71333 |
22.34 |
| 2026-10-05 00:00 |
14:36:53.39 |
-60:20:47.1 |
HIP 71333 |
23.18 |
| 2026-10-05 12:00 |
14:37:11.97 |
-60:20:30.6 |
HIP 71333 |
24.23 |
| 2026-10-06 00:00 |
14:37:30.61 |
-60:20:14.9 |
HIP 71333 |
25.47 |
| 2026-10-06 12:00 |
14:37:49.29 |
-60:20:00.0 |
HIP 71333 |
26.86 |
| 2026-10-07 00:00 |
14:38:08.02 |
-60:19:45.7 |
HIP 71650 |
26.01 |
| 2026-10-07 12:00 |
14:38:26.80 |
-60:19:32.2 |
HIP 71650 |
25.10 |
| 2026-10-08 00:00 |
14:38:45.63 |
-60:19:19.4 |
HIP 71650 |
24.39 |
| 2026-10-08 12:00 |
14:39:04.50 |
-60:19:07.3 |
HIP 71650 |
23.91 |
| 2026-10-09 00:00 |
14:39:23.42 |
-60:18:56.0 |
HIP 71709 |
23.64 |
| 2026-10-09 12:00 |
14:39:42.38 |
-60:18:45.4 |
HIP 71709 |
23.06 |
| 2026-10-10 00:00 |
14:40:01.39 |
-60:18:35.5 |
HIP 71709 |
22.72 |
| 2026-10-10 12:00 |
14:40:20.44 |
-60:18:26.3 |
HIP 71709 |
22.64 |
| 2026-10-11 00:00 |
14:40:39.53 |
-60:18:17.9 |
HIP 71709 |
22.82 |