| 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) |
| 2026-07-29 00:00 |
09:42:56.11 |
-28:02:21.7 |
HIP 47758 |
23.33 |
| 2026-07-29 12:00 |
09:43:07.04 |
-28:03:05.3 |
HIP 47758 |
22.20 |
| 2026-07-30 00:00 |
09:43:17.98 |
-28:03:49.6 |
HIP 47758 |
21.32 |
| 2026-07-30 12:00 |
09:43:28.94 |
-28:04:34.7 |
HIP 47758 |
20.73 |
| 2026-07-31 00:00 |
09:43:39.92 |
-28:05:20.5 |
HIP 47758 |
20.45 |
| 2026-07-31 12:00 |
09:43:50.91 |
-28:06:07.0 |
HIP 47758 |
20.49 |
| 2026-08-01 00:00 |
09:44:01.92 |
-28:06:54.3 |
HIP 47758 |
20.85 |
| 2026-08-01 12:00 |
09:44:12.94 |
-28:07:42.2 |
HIP 47758 |
21.53 |
| 2026-08-02 00:00 |
09:44:23.98 |
-28:08:30.9 |
HIP 47878 |
21.21 |
| 2026-08-02 12:00 |
09:44:35.03 |
-28:09:20.3 |
HIP 47878 |
19.02 |
| 2026-08-03 00:00 |
09:44:46.09 |
-28:10:10.5 |
HIP 47878 |
16.92 |
| 2026-08-03 12:00 |
09:44:57.17 |
-28:11:01.3 |
HIP 47878 |
14.96 |
| 2026-08-04 00:00 |
09:45:08.26 |
-28:11:52.9 |
HIP 47878 |
13.20 |
| 2026-08-04 12:00 |
09:45:19.36 |
-28:12:45.2 |
HIP 47878 |
11.74 |
| 2026-08-05 00:00 |
09:45:30.47 |
-28:13:38.2 |
HIP 47878 |
10.70 |
| 2026-08-05 12:00 |
09:45:41.60 |
-28:14:32.0 |
HIP 47878 |
10.23 |
| 2026-08-06 00:00 |
09:45:52.73 |
-28:15:26.4 |
HIP 47878 |
10.40 |
| 2026-08-06 12:00 |
09:46:03.88 |
-28:16:21.6 |
HIP 47878 |
11.19 |
| 2026-08-07 00:00 |
09:46:15.03 |
-28:17:17.5 |
HIP 47878 |
12.48 |
| 2026-08-07 12:00 |
09:46:26.20 |
-28:18:14.1 |
HIP 47878 |
14.14 |
| 2026-08-08 00:00 |
09:46:37.37 |
-28:19:11.4 |
HIP 48047 |
14.31 |
| 2026-08-08 12:00 |
09:46:48.55 |
-28:20:09.4 |
HIP 48047 |
11.69 |
| 2026-08-09 00:00 |
09:46:59.74 |
-28:21:08.1 |
HIP 48047 |
9.08 |
| 2026-08-09 12:00 |
09:47:10.94 |
-28:22:07.5 |
HIP 48047 |
6.50 |
| 2026-08-10 00:00 |
09:47:22.14 |
-28:23:07.7 |
HIP 48047 |
4.02 |
| 2026-08-10 12:00 |
09:47:33.35 |
-28:24:08.5 |
HIP 48047 |
2.05 |
| 2026-08-11 00:00 |
09:47:44.56 |
-28:25:10.1 |
HIP 48047 |
2.56 |
| 2026-08-11 12:00 |
09:47:55.78 |
-28:26:12.3 |
HIP 48047 |
4.82 |
| 2026-08-12 00:00 |
09:48:07.01 |
-28:27:15.3 |
HIP 48047 |
7.37 |
| 2026-08-12 12:00 |
09:48:18.23 |
-28:28:18.9 |
HIP 48047 |
10.00 |
| 2026-08-13 00:00 |
09:48:29.46 |
-28:29:23.3 |
HIP 48047 |
12.66 |
| 2026-08-13 12:00 |
09:48:40.70 |
-28:30:28.3 |
HIP 48047 |
15.33 |
| 2026-08-14 00:00 |
09:48:51.93 |
-28:31:34.0 |
HIP 48047 |
18.02 |
| 2026-08-14 12:00 |
09:49:03.17 |
-28:32:40.5 |
HIP 48047 |
20.72 |
| 2026-08-15 00:00 |
09:49:14.41 |
-28:33:47.6 |
HIP 48237 |
22.04 |
| 2026-08-15 12:00 |
09:49:25.65 |
-28:34:55.4 |
HIP 48237 |
19.93 |
| 2026-08-16 00:00 |
09:49:36.89 |
-28:36:03.8 |
HIP 48237 |
17.97 |
| 2026-08-16 12:00 |
09:49:48.12 |
-28:37:13.0 |
HIP 48237 |
16.22 |
| 2026-08-17 00:00 |
09:49:59.36 |
-28:38:22.8 |
HIP 48237 |
14.75 |
| 2026-08-17 12:00 |
09:50:10.60 |
-28:39:33.3 |
HIP 48237 |
13.67 |
| 2026-08-18 00:00 |
09:50:21.83 |
-28:40:44.5 |
HIP 48237 |
13.06 |
| 2026-08-18 12:00 |
09:50:33.06 |
-28:41:56.4 |
HIP 48237 |
12.99 |
| 2026-08-19 00:00 |
09:50:44.29 |
-28:43:08.9 |
HIP 48237 |
13.49 |