| 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 |
9.999 |
| 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) |
| 2026-06-01 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 |
| 2026-06-02 12:00 |
09:26:16.63 |
-28:00:12.3 |
HIP 46140 |
22.85 |
| 2026-06-03 00:00 |
09:26:22.36 |
-27:59:33.4 |
HIP 46140 |
24.13 |
| 2026-06-03 12:00 |
09:26:28.17 |
-27:58:55.1 |
HIP 46140 |
25.43 |
| 2026-06-04 00:00 |
09:26:34.05 |
-27:58:17.5 |
HIP 46140 |
26.77 |
| 2026-06-04 12:00 |
09:26:40.01 |
-27:57:40.5 |
HIP 46382 |
28.04 |
| 2026-06-05 00:00 |
09:26:46.03 |
-27:57:04.1 |
HIP 46382 |
28.15 |
| 2026-06-05 12:00 |
09:26:52.13 |
-27:56:28.4 |
HIP 46382 |
28.31 |
| 2026-06-06 00:00 |
09:26:58.30 |
-27:55:53.3 |
HIP 46382 |
28.54 |
| 2026-06-06 12:00 |
09:27:04.54 |
-27:55:18.9 |
HIP 46382 |
28.82 |
| 2026-06-07 00:00 |
09:27:10.85 |
-27:54:45.2 |
HIP 46382 |
29.17 |
| 2026-06-07 12:00 |
09:27:17.23 |
-27:54:12.1 |
HIP 46382 |
29.57 |
| 2026-06-08 00:00 |
09:27:23.68 |
-27:53:39.7 |
HIP 46541 |
28.72 |
| 2026-06-08 12:00 |
09:27:30.20 |
-27:53:07.9 |
HIP 46541 |
27.21 |
| 2026-06-09 00:00 |
09:27:36.79 |
-27:52:36.9 |
HIP 46541 |
25.68 |
| 2026-06-09 12:00 |
09:27:43.44 |
-27:52:06.5 |
HIP 46541 |
24.15 |
| 2026-06-10 00:00 |
09:27:50.16 |
-27:51:36.7 |
HIP 46541 |
22.60 |
| 2026-06-10 12:00 |
09:27:56.95 |
-27:51:07.7 |
HIP 46541 |
21.05 |
| 2026-06-11 00:00 |
09:28:03.81 |
-27:50:39.4 |
HIP 46541 |
19.48 |
| 2026-06-11 12:00 |
09:28:10.73 |
-27:50:11.7 |
HIP 46541 |
17.90 |
| 2026-06-12 00:00 |
09:28:17.72 |
-27:49:44.7 |
HIP 46541 |
16.32 |
| 2026-06-12 12:00 |
09:28:24.78 |
-27:49:18.4 |
HIP 46541 |
14.73 |
| 2026-06-13 00:00 |
09:28:31.90 |
-27:48:52.9 |
HIP 46541 |
13.13 |
| 2026-06-13 12:00 |
09:28:39.08 |
-27:48:28.0 |
HIP 46541 |
11.52 |
| 2026-06-14 00:00 |
09:28:46.33 |
-27:48:03.8 |
HIP 46541 |
9.91 |
| 2026-06-14 12:00 |
09:28:53.65 |
-27:47:40.3 |
HIP 46541 |
8.31 |
| 2026-06-15 00:00 |
09:29:01.02 |
-27:47:17.6 |
HIP 46541 |
6.71 |
| 2026-06-15 12:00 |
09:29:08.46 |
-27:46:55.6 |
HIP 46541 |
5.15 |
| 2026-06-16 00:00 |
09:29:15.96 |
-27:46:34.2 |
HIP 46541 |
3.69 |
| 2026-06-16 12:00 |
09:29:23.52 |
-27:46:13.6 |
HIP 46541 |
2.52 |
| 2026-06-17 00:00 |
09:29:31.14 |
-27:45:53.7 |
HIP 46541 |
2.20 |
| 2026-06-17 12:00 |
09:29:38.83 |
-27:45:34.6 |
HIP 46541 |
3.04 |
| 2026-06-18 00:00 |
09:29:46.57 |
-27:45:16.1 |
HIP 46541 |
4.43 |
| 2026-06-18 12:00 |
09:29:54.37 |
-27:44:58.4 |
HIP 46541 |
6.01 |
| 2026-06-19 00:00 |
09:30:02.23 |
-27:44:41.4 |
HIP 46541 |
7.67 |
| 2026-06-19 12:00 |
09:30:10.15 |
-27:44:25.2 |
HIP 46541 |
9.38 |
| 2026-06-20 00:00 |
09:30:18.13 |
-27:44:09.6 |
HIP 46541 |
11.11 |
| 2026-06-20 12:00 |
09:30:26.16 |
-27:43:54.8 |
HIP 46541 |
12.87 |
| 2026-06-21 00:00 |
09:30:34.25 |
-27:43:40.8 |
HIP 46541 |
14.64 |
| 2026-06-21 12:00 |
09:30:42.40 |
-27:43:27.4 |
HIP 46541 |
16.43 |
| 2026-06-22 00:00 |
09:30:50.60 |
-27:43:14.8 |
HIP 46541 |
18.23 |