| Parameter |
Value |
| Designation |
C/2021 Q3 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-01-26T01:52:57.941760Z |
| Orbit solution date (soln_date, UTC) |
2023-03-20T19:42:36Z |
| Obs used |
180 |
| NEO |
- |
| M1 |
6.900 |
| K1 |
11.750 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2021-08-26T07:07:01.228800Z |
| Discovery magnitude (MPC) |
19.02 o |
| Discovery observatory (MPC) |
T05 · ATLAS-HKO, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-01-10.0000000 |
| e |
0.93033551 |
| q (au) |
5.204636 |
| a (au) |
74.710023 |
| i (deg) |
77.777282 |
| Ω (om, deg) |
307.900611 |
| ω (w, deg) |
114.090847 |
| M (ma, deg) |
359.975460 |
Magnitude
Scatter + Global Linear
$$
M_a = (3.505 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
3.505 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
08:17:44.18 |
-12:37:48.1 |
HIP 40693 |
9.66 |
| 2026-03-26 12:00 |
08:17:39.07 |
-12:37:01.3 |
HIP 40693 |
10.93 |
| 2026-03-27 00:00 |
08:17:34.05 |
-12:36:14.4 |
HIP 40553 |
10.25 |
| 2026-03-27 12:00 |
08:17:29.12 |
-12:35:27.5 |
HIP 40553 |
9.02 |
| 2026-03-28 00:00 |
08:17:24.29 |
-12:34:40.7 |
HIP 40553 |
7.88 |
| 2026-03-28 12:00 |
08:17:19.56 |
-12:33:53.8 |
HIP 40553 |
6.86 |
| 2026-03-29 00:00 |
08:17:14.92 |
-12:33:06.9 |
HIP 40553 |
6.02 |
| 2026-03-29 12:00 |
08:17:10.37 |
-12:32:20.0 |
HIP 40553 |
5.42 |
| 2026-03-30 00:00 |
08:17:05.92 |
-12:31:33.1 |
HIP 40553 |
5.14 |
| 2026-03-30 12:00 |
08:17:01.56 |
-12:30:46.3 |
HIP 40553 |
5.20 |
| 2026-03-31 00:00 |
08:16:57.29 |
-12:29:59.5 |
HIP 40553 |
5.60 |
| 2026-03-31 12:00 |
08:16:53.12 |
-12:29:12.8 |
HIP 40553 |
6.24 |
| 2026-04-01 00:00 |
08:16:49.05 |
-12:28:26.0 |
HIP 40553 |
7.05 |
| 2026-04-01 12:00 |
08:16:45.07 |
-12:27:39.4 |
HIP 40553 |
7.98 |
| 2026-04-02 00:00 |
08:16:41.18 |
-12:26:52.8 |
HIP 40553 |
8.98 |
| 2026-04-02 12:00 |
08:16:37.39 |
-12:26:06.2 |
HIP 40553 |
10.01 |
| 2026-04-03 00:00 |
08:16:33.69 |
-12:25:19.8 |
HIP 40553 |
11.08 |
| 2026-04-03 12:00 |
08:16:30.09 |
-12:24:33.4 |
HIP 40553 |
12.15 |
| 2026-04-04 00:00 |
08:16:26.58 |
-12:23:47.1 |
HIP 40553 |
13.23 |
| 2026-04-04 12:00 |
08:16:23.17 |
-12:23:00.9 |
HIP 40553 |
14.30 |
| 2026-04-05 00:00 |
08:16:19.85 |
-12:22:14.8 |
HIP 40553 |
15.38 |
| 2026-04-05 12:00 |
08:16:16.62 |
-12:21:28.8 |
HIP 40553 |
16.44 |
| 2026-04-06 00:00 |
08:16:13.49 |
-12:20:43.0 |
HIP 40553 |
17.50 |
| 2026-04-06 12:00 |
08:16:10.46 |
-12:19:57.2 |
HIP 40553 |
18.54 |
| 2026-04-07 00:00 |
08:16:07.52 |
-12:19:11.6 |
HIP 40553 |
19.57 |
| 2026-04-07 12:00 |
08:16:04.67 |
-12:18:26.1 |
HIP 40553 |
20.59 |
| 2026-04-08 00:00 |
08:16:01.92 |
-12:17:40.7 |
HIP 40553 |
21.59 |
| 2026-04-08 12:00 |
08:15:59.26 |
-12:16:55.5 |
HIP 40553 |
22.58 |
| 2026-04-09 00:00 |
08:15:56.70 |
-12:16:10.5 |
HIP 40553 |
23.55 |
| 2026-04-09 12:00 |
08:15:54.23 |
-12:15:25.6 |
HIP 40553 |
24.51 |
| 2026-04-10 00:00 |
08:15:51.86 |
-12:14:40.9 |
HIP 40553 |
25.46 |
| 2026-04-10 12:00 |
08:15:49.58 |
-12:13:56.3 |
HIP 40553 |
26.38 |
| 2026-04-11 00:00 |
08:15:47.39 |
-12:13:11.9 |
HIP 40553 |
27.30 |
| 2026-04-11 12:00 |
08:15:45.30 |
-12:12:27.8 |
HIP 40553 |
28.19 |
| 2026-04-12 00:00 |
08:15:43.31 |
-12:11:43.8 |
HIP 40553 |
29.07 |
| 2026-04-12 12:00 |
08:15:41.40 |
-12:11:00.0 |
HIP 40553 |
29.94 |
| 2026-04-13 00:00 |
08:15:39.60 |
-12:10:16.4 |
HIP 40553 |
30.78 |
| 2026-04-13 12:00 |
08:15:37.88 |
-12:09:33.0 |
HIP 40553 |
31.62 |
| 2026-04-14 00:00 |
08:15:36.26 |
-12:08:49.9 |
HIP 40553 |
32.43 |
| 2026-04-14 12:00 |
08:15:34.73 |
-12:08:07.0 |
HIP 40553 |
33.23 |
| 2026-04-15 00:00 |
08:15:33.30 |
-12:07:24.3 |
HIP 40553 |
34.02 |
| 2026-04-15 12:00 |
08:15:31.96 |
-12:06:41.8 |
HIP 40553 |
34.79 |
| 2026-04-16 00:00 |
08:15:30.71 |
-12:05:59.7 |
HIP 40553 |
35.54 |