| Parameter |
Value |
| Designation |
C/2021 S1 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-02-28T22:41:40.444800Z |
| Orbit solution date (soln_date, UTC) |
2024-06-06T23:12:23Z |
| Obs used |
476 |
| NEO |
- |
| M1 |
6.700 |
| K1 |
10.000 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2021-09-27T13:41:00.096000Z |
| Discovery magnitude (MPC) |
17.82 o |
| Discovery observatory (MPC) |
T05 · ATLAS-HKO, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-03-23.0000000 |
| e |
1.00095649 |
| q (au) |
6.119212 |
| a (au) |
-6397.577104 |
| i (deg) |
52.088959 |
| Ω (om, deg) |
299.873636 |
| ω (w, deg) |
148.188635 |
| M (ma, deg) |
0.000042 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.453 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.453 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.717 |
| k |
0.800 |
| 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) |
| 2026-05-12 00:00 |
09:23:25.40 |
-28:37:12.4 |
HIP 46026 |
13.14 |
| 2026-05-12 12:00 |
09:23:27.58 |
-28:36:10.1 |
HIP 46026 |
14.26 |
| 2026-05-13 00:00 |
09:23:29.85 |
-28:35:08.3 |
HIP 46026 |
15.38 |
| 2026-05-13 12:00 |
09:23:32.21 |
-28:34:06.8 |
HIP 46026 |
16.51 |
| 2026-05-14 00:00 |
09:23:34.66 |
-28:33:05.8 |
HIP 46026 |
17.63 |
| 2026-05-14 12:00 |
09:23:37.20 |
-28:32:05.3 |
HIP 46026 |
18.76 |
| 2026-05-15 00:00 |
09:23:39.83 |
-28:31:05.1 |
HIP 46026 |
19.89 |
| 2026-05-15 12:00 |
09:23:42.56 |
-28:30:05.5 |
HIP 46026 |
21.02 |
| 2026-05-16 00:00 |
09:23:45.37 |
-28:29:06.3 |
HIP 46026 |
22.15 |
| 2026-05-16 12:00 |
09:23:48.26 |
-28:28:07.6 |
HIP 46026 |
23.28 |
| 2026-05-17 00:00 |
09:23:51.25 |
-28:27:09.4 |
HIP 46026 |
24.42 |
| 2026-05-17 12:00 |
09:23:54.33 |
-28:26:11.7 |
HIP 46026 |
25.56 |
| 2026-05-18 00:00 |
09:23:57.49 |
-28:25:14.4 |
HIP 46242 |
25.74 |
| 2026-05-18 12:00 |
09:24:00.74 |
-28:24:17.7 |
HIP 46140 |
25.09 |
| 2026-05-19 00:00 |
09:24:04.08 |
-28:23:21.4 |
HIP 46140 |
23.99 |
| 2026-05-19 12:00 |
09:24:07.50 |
-28:22:25.7 |
HIP 46140 |
22.90 |
| 2026-05-20 00:00 |
09:24:11.01 |
-28:21:30.5 |
HIP 46140 |
21.82 |
| 2026-05-20 12:00 |
09:24:14.60 |
-28:20:35.8 |
HIP 46140 |
20.76 |
| 2026-05-21 00:00 |
09:24:18.28 |
-28:19:41.6 |
HIP 46140 |
19.73 |
| 2026-05-21 12:00 |
09:24:22.05 |
-28:18:48.0 |
HIP 46140 |
18.72 |
| 2026-05-22 00:00 |
09:24:25.90 |
-28:17:54.9 |
HIP 46140 |
17.75 |
| 2026-05-22 12:00 |
09:24:29.83 |
-28:17:02.4 |
HIP 46140 |
16.82 |
| 2026-05-23 00:00 |
09:24:33.84 |
-28:16:10.4 |
HIP 46140 |
15.94 |
| 2026-05-23 12:00 |
09:24:37.94 |
-28:15:18.9 |
HIP 46140 |
15.12 |
| 2026-05-24 00:00 |
09:24:42.12 |
-28:14:28.0 |
HIP 46140 |
14.37 |
| 2026-05-24 12:00 |
09:24:46.39 |
-28:13:37.7 |
HIP 46140 |
13.71 |
| 2026-05-25 00:00 |
09:24:50.73 |
-28:12:47.9 |
HIP 46140 |
13.15 |
| 2026-05-25 12:00 |
09:24:55.16 |
-28:11:58.7 |
HIP 46140 |
12.71 |
| 2026-05-26 00:00 |
09:24:59.66 |
-28:11:10.1 |
HIP 46140 |
12.40 |
| 2026-05-26 12:00 |
09:25:04.25 |
-28:10:22.1 |
HIP 46140 |
12.24 |
| 2026-05-27 00:00 |
09:25:08.92 |
-28:09:34.6 |
HIP 46140 |
12.23 |
| 2026-05-27 12:00 |
09:25:13.66 |
-28:08:47.8 |
HIP 46140 |
12.38 |
| 2026-05-28 00:00 |
09:25:18.49 |
-28:08:01.5 |
HIP 46140 |
12.68 |
| 2026-05-28 12:00 |
09:25:23.39 |
-28:07:15.8 |
HIP 46140 |
13.13 |
| 2026-05-29 00:00 |
09:25:28.37 |
-28:06:30.7 |
HIP 46140 |
13.71 |
| 2026-05-29 12:00 |
09:25:33.43 |
-28:05:46.2 |
HIP 46140 |
14.41 |
| 2026-05-30 00:00 |
09:25:38.56 |
-28:05:02.3 |
HIP 46140 |
15.22 |
| 2026-05-30 12:00 |
09:25:43.77 |
-28:04:19.0 |
HIP 46140 |
16.12 |
| 2026-05-31 00:00 |
09:25:49.06 |
-28:03:36.4 |
HIP 46140 |
17.10 |
| 2026-05-31 12:00 |
09:25:54.42 |
-28:02:54.3 |
HIP 46140 |
18.14 |
| 2026-06-01 00:00 |
09:25:59.86 |
-28:02:12.9 |
HIP 46140 |
19.25 |
| 2026-06-01 12:00 |
09:26:05.38 |
-28:01:32.1 |
HIP 46140 |
20.41 |
| 2026-06-02 00:00 |
09:26:10.96 |
-28:00:51.9 |
HIP 46140 |
21.61 |