| Parameter |
Value |
| Designation |
C/2021 K1 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-05-04T13:50:34.362240Z |
| Orbit solution date (soln_date, UTC) |
2022-07-19T01:12:51Z |
| Obs used |
676 |
| NEO |
- |
| M1 |
6.600 |
| K1 |
19.000 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2021-05-24T14:32:49.718400Z |
| Discovery magnitude (MPC) |
16.39 o |
| Discovery observatory (MPC) |
T05 · ATLAS-HKO, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-08-19.0000000 |
| e |
0.80399384 |
| q (au) |
2.497832 |
| a (au) |
12.743639 |
| i (deg) |
16.276067 |
| Ω (om, deg) |
140.905656 |
| ω (w, deg) |
184.303821 |
| M (ma, deg) |
2.305686 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.271 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.271 |
| n |
6.000 |
| gf |
0.800 |
| gb |
-0.840 |
| k |
0.995 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2020-04-20 |
2020-08-12 |
-4.6047 |
+5.290 |
| 2021-05-14 |
2021-11-24 |
-4.0011 |
+1.844 |
| 2021-11-24 |
2022-01-31 |
-10.7283 |
+4.958 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
06:54:16.88 |
+14:02:31.6 |
HIP 33258 |
17.14 |
| 2026-05-12 12:00 |
06:54:24.64 |
+14:02:43.4 |
HIP 33258 |
15.62 |
| 2026-05-13 00:00 |
06:54:32.45 |
+14:02:55.0 |
HIP 33258 |
14.19 |
| 2026-05-13 12:00 |
06:54:40.31 |
+14:03:06.3 |
HIP 33258 |
12.88 |
| 2026-05-14 00:00 |
06:54:48.22 |
+14:03:17.4 |
HIP 33258 |
11.73 |
| 2026-05-14 12:00 |
06:54:56.19 |
+14:03:28.2 |
HIP 33258 |
10.80 |
| 2026-05-15 00:00 |
06:55:04.20 |
+14:03:38.8 |
HIP 33258 |
10.17 |
| 2026-05-15 12:00 |
06:55:12.27 |
+14:03:49.2 |
HIP 33258 |
9.89 |
| 2026-05-16 00:00 |
06:55:20.39 |
+14:03:59.4 |
HIP 33258 |
10.00 |
| 2026-05-16 12:00 |
06:55:28.56 |
+14:04:09.3 |
HIP 33258 |
10.50 |
| 2026-05-17 00:00 |
06:55:36.78 |
+14:04:18.9 |
HIP 33258 |
11.34 |
| 2026-05-17 12:00 |
06:55:45.05 |
+14:04:28.4 |
HIP 33258 |
12.46 |
| 2026-05-18 00:00 |
06:55:53.36 |
+14:04:37.6 |
HIP 33258 |
13.79 |
| 2026-05-18 12:00 |
06:56:01.73 |
+14:04:46.5 |
HIP 33258 |
15.29 |
| 2026-05-19 00:00 |
06:56:10.14 |
+14:04:55.3 |
HIP 33258 |
16.91 |
| 2026-05-19 12:00 |
06:56:18.60 |
+14:05:03.8 |
HIP 33258 |
18.63 |
| 2026-05-20 00:00 |
06:56:27.10 |
+14:05:12.0 |
HIP 33258 |
20.42 |
| 2026-05-20 12:00 |
06:56:35.65 |
+14:05:20.0 |
HIP 33258 |
22.27 |
| 2026-05-21 00:00 |
06:56:44.24 |
+14:05:27.8 |
HIP 33529 |
21.60 |
| 2026-05-21 12:00 |
06:56:52.88 |
+14:05:35.4 |
HIP 33529 |
19.63 |
| 2026-05-22 00:00 |
06:57:01.57 |
+14:05:42.7 |
HIP 33529 |
17.68 |
| 2026-05-22 12:00 |
06:57:10.29 |
+14:05:49.7 |
HIP 33529 |
15.77 |
| 2026-05-23 00:00 |
06:57:19.06 |
+14:05:56.6 |
HIP 33529 |
13.90 |
| 2026-05-23 12:00 |
06:57:27.88 |
+14:06:03.2 |
HIP 33529 |
12.12 |
| 2026-05-24 00:00 |
06:57:36.73 |
+14:06:09.5 |
HIP 33529 |
10.47 |
| 2026-05-24 12:00 |
06:57:45.63 |
+14:06:15.7 |
HIP 33529 |
9.03 |
| 2026-05-25 00:00 |
06:57:54.56 |
+14:06:21.5 |
HIP 33529 |
7.92 |
| 2026-05-25 12:00 |
06:58:03.54 |
+14:06:27.2 |
HIP 33529 |
7.31 |
| 2026-05-26 00:00 |
06:58:12.56 |
+14:06:32.6 |
HIP 33529 |
7.32 |
| 2026-05-26 12:00 |
06:58:21.61 |
+14:06:37.8 |
HIP 33529 |
7.97 |
| 2026-05-27 00:00 |
06:58:30.71 |
+14:06:42.7 |
HIP 33529 |
9.13 |
| 2026-05-27 12:00 |
06:58:39.84 |
+14:06:47.5 |
HIP 33540 |
10.37 |
| 2026-05-28 00:00 |
06:58:49.01 |
+14:06:51.9 |
HIP 33540 |
11.82 |
| 2026-05-28 12:00 |
06:58:58.22 |
+14:06:56.2 |
HIP 33540 |
13.49 |
| 2026-05-29 00:00 |
06:59:07.47 |
+14:07:00.2 |
HIP 33651 |
13.54 |
| 2026-05-29 12:00 |
06:59:16.75 |
+14:07:04.0 |
HIP 33651 |
12.82 |
| 2026-05-30 00:00 |
06:59:26.07 |
+14:07:07.5 |
HIP 33651 |
12.47 |
| 2026-05-30 12:00 |
06:59:35.42 |
+14:07:10.8 |
HIP 33651 |
12.52 |
| 2026-05-31 00:00 |
06:59:44.81 |
+14:07:13.9 |
HIP 33651 |
12.99 |
| 2026-05-31 12:00 |
06:59:54.23 |
+14:07:16.7 |
HIP 33651 |
13.83 |
| 2026-06-01 00:00 |
07:00:03.69 |
+14:07:19.3 |
HIP 33651 |
14.98 |
| 2026-06-01 12:00 |
07:00:13.18 |
+14:07:21.7 |
HIP 33651 |
16.38 |
| 2026-06-02 00:00 |
07:00:22.70 |
+14:07:23.8 |
HIP 33651 |
17.97 |