| Parameter |
Value |
| Designation |
C/2021 F1 (Lemmon-PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-04-06T21:01:27.013440Z |
| Orbit solution date (soln_date, UTC) |
2023-04-24T19:06:41Z |
| Obs used |
403 |
| NEO |
- |
| M1 |
12.900 |
| K1 |
10.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-03-03.0000000 |
| e |
0.99570134 |
| q (au) |
0.995447 |
| a (au) |
231.571420 |
| i (deg) |
107.324992 |
| Ω (om, deg) |
203.451604 |
| ω (w, deg) |
146.826095 |
| M (ma, deg) |
359.990246 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.444 + 4.948\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.444 |
| n |
4.948 |
| gf |
0.997 |
| gb |
-1.000 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2022-01-07 |
2022-03-31 |
+7.4996 |
-2.051 |
| 2022-05-30 |
2022-09-02 |
+5.5948 |
-3.888 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
12:36:07.70 |
-77:34:18.7 |
HIP 61183 |
14.88 |
| 2026-03-26 12:00 |
12:35:29.35 |
-77:33:57.8 |
HIP 61183 |
13.38 |
| 2026-03-27 00:00 |
12:34:51.02 |
-77:33:35.5 |
HIP 61183 |
12.07 |
| 2026-03-27 12:00 |
12:34:12.70 |
-77:33:11.6 |
HIP 61183 |
11.03 |
| 2026-03-28 00:00 |
12:33:34.41 |
-77:32:46.3 |
HIP 61183 |
10.33 |
| 2026-03-28 12:00 |
12:32:56.14 |
-77:32:19.5 |
HIP 61183 |
10.05 |
| 2026-03-29 00:00 |
12:32:17.92 |
-77:31:51.1 |
HIP 61183 |
10.23 |
| 2026-03-29 12:00 |
12:31:39.74 |
-77:31:21.4 |
HIP 61183 |
10.84 |
| 2026-03-30 00:00 |
12:31:01.61 |
-77:30:50.1 |
HIP 61183 |
11.83 |
| 2026-03-30 12:00 |
12:30:23.53 |
-77:30:17.3 |
HIP 61183 |
13.11 |
| 2026-03-31 00:00 |
12:29:45.52 |
-77:29:43.1 |
HIP 61183 |
14.61 |
| 2026-03-31 12:00 |
12:29:07.58 |
-77:29:07.4 |
HIP 61183 |
16.26 |
| 2026-04-01 00:00 |
12:28:29.71 |
-77:28:30.2 |
HIP 61183 |
18.03 |
| 2026-04-01 12:00 |
12:27:51.93 |
-77:27:51.6 |
HIP 60526 |
18.68 |
| 2026-04-02 00:00 |
12:27:14.23 |
-77:27:11.5 |
HIP 60526 |
16.96 |
| 2026-04-02 12:00 |
12:26:36.62 |
-77:26:29.9 |
HIP 60526 |
15.33 |
| 2026-04-03 00:00 |
12:25:59.11 |
-77:25:46.9 |
HIP 60526 |
13.83 |
| 2026-04-03 12:00 |
12:25:21.71 |
-77:25:02.5 |
HIP 60526 |
12.51 |
| 2026-04-04 00:00 |
12:24:44.42 |
-77:24:16.6 |
HIP 60526 |
11.43 |
| 2026-04-04 12:00 |
12:24:07.24 |
-77:23:29.2 |
HIP 60526 |
10.67 |
| 2026-04-05 00:00 |
12:23:30.19 |
-77:22:40.4 |
HIP 60526 |
10.30 |
| 2026-04-05 12:00 |
12:22:53.27 |
-77:21:50.2 |
HIP 60526 |
10.37 |
| 2026-04-06 00:00 |
12:22:16.48 |
-77:20:58.5 |
HIP 60526 |
10.87 |
| 2026-04-06 12:00 |
12:21:39.83 |
-77:20:05.5 |
HIP 60526 |
11.74 |
| 2026-04-07 00:00 |
12:21:03.32 |
-77:19:11.0 |
HIP 60526 |
12.93 |
| 2026-04-07 12:00 |
12:20:26.96 |
-77:18:15.1 |
HIP 60526 |
14.34 |
| 2026-04-08 00:00 |
12:19:50.76 |
-77:17:17.8 |
HIP 60526 |
15.93 |
| 2026-04-08 12:00 |
12:19:14.73 |
-77:16:19.1 |
HIP 60526 |
17.64 |
| 2026-04-09 00:00 |
12:18:38.85 |
-77:15:19.0 |
HIP 60526 |
19.45 |
| 2026-04-09 12:00 |
12:18:03.16 |
-77:14:17.5 |
HIP 60526 |
21.33 |
| 2026-04-10 00:00 |
12:17:27.63 |
-77:13:14.6 |
HIP 60526 |
23.26 |
| 2026-04-10 12:00 |
12:16:52.29 |
-77:12:10.4 |
HIP 60526 |
25.24 |
| 2026-04-11 00:00 |
12:16:17.14 |
-77:11:04.8 |
HIP 60119 |
25.85 |
| 2026-04-11 12:00 |
12:15:42.18 |
-77:09:57.8 |
HIP 60119 |
25.85 |
| 2026-04-12 00:00 |
12:15:07.41 |
-77:08:49.5 |
HIP 60119 |
26.03 |
| 2026-04-12 12:00 |
12:14:32.85 |
-77:07:39.9 |
HIP 60119 |
26.38 |
| 2026-04-13 00:00 |
12:13:58.50 |
-77:06:28.9 |
HIP 60119 |
26.90 |
| 2026-04-13 12:00 |
12:13:24.35 |
-77:05:16.6 |
HIP 60119 |
27.58 |
| 2026-04-14 00:00 |
12:12:50.43 |
-77:04:03.0 |
HIP 60119 |
28.41 |
| 2026-04-14 12:00 |
12:12:16.72 |
-77:02:48.1 |
HIP 59245 |
26.72 |
| 2026-04-15 00:00 |
12:11:43.24 |
-77:01:31.8 |
HIP 59245 |
24.84 |
| 2026-04-15 12:00 |
12:11:09.99 |
-77:00:14.3 |
HIP 59245 |
23.00 |
| 2026-04-16 00:00 |
12:10:36.97 |
-76:58:55.5 |
HIP 59245 |
21.24 |