C/2021 Q3 (ATLAS)
| 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) |
| 2026-02-03 00:00 |
08:33:17.15 |
-13:29:40.4 |
HIP 41965 |
7.68 |
| 2026-02-03 12:00 |
08:33:05.30 |
-13:29:39.4 |
HIP 41965 |
7.89 |
| 2026-02-04 00:00 |
08:32:53.48 |
-13:29:37.6 |
HIP 41965 |
9.07 |
| 2026-02-04 12:00 |
08:32:41.68 |
-13:29:35.0 |
HIP 41965 |
10.91 |
| 2026-02-05 00:00 |
08:32:29.91 |
-13:29:31.6 |
HIP 41965 |
13.12 |
| 2026-02-05 12:00 |
08:32:18.15 |
-13:29:27.4 |
HIP 41965 |
15.55 |
| 2026-02-06 00:00 |
08:32:06.43 |
-13:29:22.4 |
HIP 41965 |
18.11 |
| 2026-02-06 12:00 |
08:31:54.73 |
-13:29:16.6 |
HIP 41965 |
20.74 |
| 2026-02-07 00:00 |
08:31:43.05 |
-13:29:10.1 |
HIP 41719 |
18.95 |
| 2026-02-07 12:00 |
08:31:31.41 |
-13:29:02.8 |
HIP 41719 |
16.11 |
| 2026-02-08 00:00 |
08:31:19.79 |
-13:28:54.7 |
HIP 41719 |
13.29 |
| 2026-02-08 12:00 |
08:31:08.21 |
-13:28:45.9 |
HIP 41719 |
10.47 |
| 2026-02-09 00:00 |
08:30:56.65 |
-13:28:36.3 |
HIP 41719 |
7.65 |
| 2026-02-09 12:00 |
08:30:45.13 |
-13:28:25.9 |
HIP 41719 |
4.85 |
| 2026-02-10 00:00 |
08:30:33.65 |
-13:28:14.8 |
HIP 41719 |
2.05 |
| 2026-02-10 12:00 |
08:30:22.20 |
-13:28:03.0 |
HIP 41719 |
0.74 |
| 2026-02-11 00:00 |
08:30:10.78 |
-13:27:50.4 |
HIP 41719 |
3.53 |
| 2026-02-11 12:00 |
08:29:59.41 |
-13:27:37.1 |
HIP 41719 |
6.30 |
| 2026-02-12 00:00 |
08:29:48.07 |
-13:27:23.1 |
HIP 41719 |
9.07 |
| 2026-02-12 12:00 |
08:29:36.77 |
-13:27:08.4 |
HIP 41719 |
11.83 |
| 2026-02-13 00:00 |
08:29:25.51 |
-13:26:52.9 |
HIP 41719 |
14.58 |
| 2026-02-13 12:00 |
08:29:14.29 |
-13:26:36.8 |
HIP 41558 |
13.97 |
| 2026-02-14 00:00 |
08:29:03.12 |
-13:26:19.9 |
HIP 41558 |
11.82 |
| 2026-02-14 12:00 |
08:28:51.99 |
-13:26:02.4 |
HIP 41558 |
9.98 |
| 2026-02-15 00:00 |
08:28:40.91 |
-13:25:44.2 |
HIP 41558 |
8.63 |
| 2026-02-15 12:00 |
08:28:29.87 |
-13:25:25.3 |
HIP 41558 |
8.01 |
| 2026-02-16 00:00 |
08:28:18.88 |
-13:25:05.7 |
HIP 41558 |
8.29 |
| 2026-02-16 12:00 |
08:28:07.93 |
-13:24:45.5 |
HIP 41558 |
9.38 |
| 2026-02-17 00:00 |
08:27:57.04 |
-13:24:24.6 |
HIP 41558 |
11.02 |
| 2026-02-17 12:00 |
08:27:46.20 |
-13:24:03.0 |
HIP 41497 |
11.55 |
| 2026-02-18 00:00 |
08:27:35.41 |
-13:23:40.9 |
HIP 41497 |
12.24 |
| 2026-02-18 12:00 |
08:27:24.67 |
-13:23:18.1 |
HIP 41497 |
13.43 |
| 2026-02-19 00:00 |
08:27:13.98 |
-13:22:54.6 |
HIP 41497 |
15.00 |
| 2026-02-19 12:00 |
08:27:03.35 |
-13:22:30.6 |
HIP 41497 |
16.83 |
| 2026-02-20 00:00 |
08:26:52.78 |
-13:22:05.9 |
HIP 41497 |
18.84 |
| 2026-02-20 12:00 |
08:26:42.26 |
-13:21:40.7 |
HIP 41497 |
20.99 |
| 2026-02-21 00:00 |
08:26:31.79 |
-13:21:14.8 |
HIP 41497 |
23.22 |
| 2026-02-21 12:00 |
08:26:21.39 |
-13:20:48.4 |
HIP 41497 |
25.50 |
| 2026-02-22 00:00 |
08:26:11.05 |
-13:20:21.4 |
HIP 41497 |
27.84 |
| 2026-02-22 12:00 |
08:26:00.76 |
-13:19:53.8 |
HIP 41497 |
30.20 |
| 2026-02-23 00:00 |
08:25:50.54 |
-13:19:25.7 |
HIP 41497 |
32.58 |
| 2026-02-23 12:00 |
08:25:40.38 |
-13:18:57.0 |
HIP 41161 |
31.83 |
| 2026-02-24 00:00 |
08:25:30.28 |
-13:18:27.7 |
HIP 41161 |
30.18 |