| Parameter |
Value |
| Designation |
C/2021 Y1 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2023-04-30T16:42:49.288320Z |
| Orbit solution date (soln_date, UTC) |
2024-04-13T16:42:29Z |
| Obs used |
1857 |
| NEO |
- |
| M1 |
12.000 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-12-26T06:50:24.691200Z |
| Discovery magnitude (MPC) |
18.99 o |
| Discovery observatory (MPC) |
T08 · ATLAS-MLO, Mauna Loa |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-10-17.0000000 |
| e |
1.00083371 |
| q (au) |
2.032510 |
| a (au) |
-2437.901109 |
| i (deg) |
77.187480 |
| Ω (om, deg) |
244.769593 |
| ω (w, deg) |
245.810207 |
| M (ma, deg) |
-0.001602 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.482 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.482 |
| n |
2.000 |
| gf |
0.833 |
| gb |
-0.807 |
| k |
0.997 |
| δ90 |
1.000 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
16:31:36.67 |
-07:44:01.7 |
HIP 80904 |
12.12 |
| 2026-06-01 12:00 |
16:31:25.11 |
-07:43:01.7 |
HIP 80891 |
11.64 |
| 2026-06-02 00:00 |
16:31:13.56 |
-07:42:02.2 |
HIP 80891 |
9.79 |
| 2026-06-02 12:00 |
16:31:02.02 |
-07:41:03.2 |
HIP 80891 |
8.64 |
| 2026-06-03 00:00 |
16:30:50.49 |
-07:40:04.5 |
HIP 80891 |
8.48 |
| 2026-06-03 12:00 |
16:30:38.99 |
-07:39:06.3 |
HIP 80840 |
8.53 |
| 2026-06-04 00:00 |
16:30:27.50 |
-07:38:08.5 |
HIP 80840 |
7.30 |
| 2026-06-04 12:00 |
16:30:16.02 |
-07:37:11.2 |
HIP 80840 |
7.21 |
| 2026-06-05 00:00 |
16:30:04.57 |
-07:36:14.2 |
HIP 80840 |
8.28 |
| 2026-06-05 12:00 |
16:29:53.13 |
-07:35:17.8 |
HIP 80840 |
10.16 |
| 2026-06-06 00:00 |
16:29:41.72 |
-07:34:21.7 |
HIP 80840 |
12.47 |
| 2026-06-06 12:00 |
16:29:30.33 |
-07:33:26.2 |
HIP 80840 |
15.01 |
| 2026-06-07 00:00 |
16:29:18.96 |
-07:32:31.0 |
HIP 80840 |
17.69 |
| 2026-06-07 12:00 |
16:29:07.62 |
-07:31:36.3 |
HIP 80840 |
20.44 |
| 2026-06-08 00:00 |
16:28:56.30 |
-07:30:42.1 |
HIP 80620 |
18.77 |
| 2026-06-08 12:00 |
16:28:45.00 |
-07:29:48.3 |
HIP 80620 |
16.41 |
| 2026-06-09 00:00 |
16:28:33.74 |
-07:28:55.0 |
HIP 80620 |
14.26 |
| 2026-06-09 12:00 |
16:28:22.50 |
-07:28:02.2 |
HIP 80620 |
12.44 |
| 2026-06-10 00:00 |
16:28:11.30 |
-07:27:09.8 |
HIP 80620 |
11.10 |
| 2026-06-10 12:00 |
16:28:00.12 |
-07:26:17.8 |
HIP 80620 |
10.41 |
| 2026-06-11 00:00 |
16:27:48.98 |
-07:25:26.4 |
HIP 80620 |
10.50 |
| 2026-06-11 12:00 |
16:27:37.86 |
-07:24:35.4 |
HIP 80620 |
11.35 |
| 2026-06-12 00:00 |
16:27:26.79 |
-07:23:44.9 |
HIP 80620 |
12.79 |
| 2026-06-12 12:00 |
16:27:15.74 |
-07:22:54.8 |
HIP 80620 |
14.65 |
| 2026-06-13 00:00 |
16:27:04.74 |
-07:22:05.2 |
HIP 80620 |
16.78 |
| 2026-06-13 12:00 |
16:26:53.77 |
-07:21:16.1 |
HIP 80620 |
19.09 |
| 2026-06-14 00:00 |
16:26:42.84 |
-07:20:27.5 |
HIP 80620 |
21.51 |
| 2026-06-14 12:00 |
16:26:31.94 |
-07:19:39.4 |
HIP 80509 |
23.82 |
| 2026-06-15 00:00 |
16:26:21.09 |
-07:18:51.8 |
HIP 80509 |
22.45 |
| 2026-06-15 12:00 |
16:26:10.28 |
-07:18:04.6 |
HIP 80509 |
21.37 |
| 2026-06-16 00:00 |
16:25:59.52 |
-07:17:17.9 |
HIP 80509 |
20.62 |
| 2026-06-16 12:00 |
16:25:48.79 |
-07:16:31.7 |
HIP 80509 |
20.23 |
| 2026-06-17 00:00 |
16:25:38.11 |
-07:15:46.0 |
HIP 80509 |
20.23 |
| 2026-06-17 12:00 |
16:25:27.48 |
-07:15:00.8 |
HIP 80509 |
20.59 |
| 2026-06-18 00:00 |
16:25:16.89 |
-07:14:16.1 |
HIP 80509 |
21.31 |
| 2026-06-18 12:00 |
16:25:06.36 |
-07:13:31.9 |
HIP 80509 |
22.34 |
| 2026-06-19 00:00 |
16:24:55.87 |
-07:12:48.1 |
HIP 80509 |
23.63 |
| 2026-06-19 12:00 |
16:24:45.43 |
-07:12:04.9 |
HIP 80509 |
25.15 |
| 2026-06-20 00:00 |
16:24:35.04 |
-07:11:22.1 |
HIP 80248 |
23.73 |
| 2026-06-20 12:00 |
16:24:24.70 |
-07:10:39.9 |
HIP 80248 |
21.22 |
| 2026-06-21 00:00 |
16:24:14.41 |
-07:09:58.1 |
HIP 80248 |
18.77 |
| 2026-06-21 12:00 |
16:24:04.18 |
-07:09:16.9 |
HIP 80248 |
16.38 |
| 2026-06-22 00:00 |
16:23:54.00 |
-07:08:36.1 |
HIP 80248 |
14.09 |