| 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) |
| 2026-09-20 00:00 |
12:27:01.25 |
-68:19:11.1 |
HIP 60576 |
13.17 |
| 2026-09-20 12:00 |
12:27:21.86 |
-68:19:03.8 |
HIP 60576 |
14.88 |
| 2026-09-21 00:00 |
12:27:42.48 |
-68:18:57.2 |
HIP 60576 |
16.62 |
| 2026-09-21 12:00 |
12:28:03.11 |
-68:18:51.4 |
HIP 60576 |
18.40 |
| 2026-09-22 00:00 |
12:28:23.74 |
-68:18:46.5 |
HIP 60576 |
20.19 |
| 2026-09-22 12:00 |
12:28:44.38 |
-68:18:42.4 |
HIP 60576 |
21.99 |
| 2026-09-23 00:00 |
12:29:05.03 |
-68:18:39.0 |
HIP 60576 |
23.81 |
| 2026-09-23 12:00 |
12:29:25.68 |
-68:18:36.5 |
HIP 60576 |
25.64 |
| 2026-09-24 00:00 |
12:29:46.33 |
-68:18:34.7 |
HIP 60825 |
27.07 |
| 2026-09-24 12:00 |
12:30:06.98 |
-68:18:33.8 |
HIP 60825 |
27.80 |
| 2026-09-25 00:00 |
12:30:27.64 |
-68:18:33.6 |
HIP 61447 |
28.21 |
| 2026-09-25 12:00 |
12:30:48.30 |
-68:18:34.3 |
HIP 61447 |
26.31 |
| 2026-09-26 00:00 |
12:31:08.95 |
-68:18:35.7 |
HIP 61447 |
24.41 |
| 2026-09-26 12:00 |
12:31:29.61 |
-68:18:37.9 |
HIP 61447 |
22.51 |
| 2026-09-27 00:00 |
12:31:50.27 |
-68:18:40.9 |
HIP 61447 |
20.61 |
| 2026-09-27 12:00 |
12:32:10.93 |
-68:18:44.7 |
HIP 61447 |
18.71 |
| 2026-09-28 00:00 |
12:32:31.58 |
-68:18:49.3 |
HIP 61447 |
16.81 |
| 2026-09-28 12:00 |
12:32:52.23 |
-68:18:54.6 |
HIP 61447 |
14.90 |
| 2026-09-29 00:00 |
12:33:12.88 |
-68:19:00.8 |
HIP 61447 |
13.00 |
| 2026-09-29 12:00 |
12:33:33.53 |
-68:19:07.7 |
HIP 61447 |
11.11 |
| 2026-09-30 00:00 |
12:33:54.17 |
-68:19:15.4 |
HIP 61447 |
9.21 |
| 2026-09-30 12:00 |
12:34:14.81 |
-68:19:23.8 |
HIP 61447 |
7.32 |
| 2026-10-01 00:00 |
12:34:35.44 |
-68:19:33.1 |
HIP 61447 |
5.43 |
| 2026-10-01 12:00 |
12:34:56.06 |
-68:19:43.1 |
HIP 61447 |
3.58 |
| 2026-10-02 00:00 |
12:35:16.68 |
-68:19:53.9 |
HIP 61447 |
1.83 |
| 2026-10-02 12:00 |
12:35:37.30 |
-68:20:05.5 |
HIP 61447 |
1.08 |
| 2026-10-03 00:00 |
12:35:57.90 |
-68:20:17.8 |
HIP 61447 |
2.50 |
| 2026-10-03 12:00 |
12:36:18.49 |
-68:20:30.9 |
HIP 61447 |
4.32 |
| 2026-10-04 00:00 |
12:36:39.08 |
-68:20:44.8 |
HIP 61447 |
6.19 |
| 2026-10-04 12:00 |
12:36:59.66 |
-68:20:59.4 |
HIP 61447 |
8.08 |
| 2026-10-05 00:00 |
12:37:20.22 |
-68:21:14.8 |
HIP 61447 |
9.98 |
| 2026-10-05 12:00 |
12:37:40.77 |
-68:21:30.9 |
HIP 61447 |
11.88 |
| 2026-10-06 00:00 |
12:38:01.31 |
-68:21:47.9 |
HIP 61447 |
13.78 |
| 2026-10-06 12:00 |
12:38:21.84 |
-68:22:05.5 |
HIP 61447 |
15.69 |
| 2026-10-07 00:00 |
12:38:42.35 |
-68:22:24.0 |
HIP 61447 |
17.60 |
| 2026-10-07 12:00 |
12:39:02.85 |
-68:22:43.2 |
HIP 61447 |
19.50 |
| 2026-10-08 00:00 |
12:39:23.33 |
-68:23:03.1 |
HIP 61447 |
21.41 |
| 2026-10-08 12:00 |
12:39:43.80 |
-68:23:23.8 |
HIP 61684 |
23.10 |
| 2026-10-09 00:00 |
12:40:04.25 |
-68:23:45.3 |
HIP 61684 |
23.28 |
| 2026-10-09 12:00 |
12:40:24.68 |
-68:24:07.5 |
HIP 61684 |
23.60 |
| 2026-10-10 00:00 |
12:40:45.09 |
-68:24:30.4 |
HIP 61684 |
24.05 |
| 2026-10-10 12:00 |
12:41:05.48 |
-68:24:54.1 |
HIP 61684 |
24.64 |
| 2026-10-11 00:00 |
12:41:25.85 |
-68:25:18.6 |
HIP 61684 |
25.33 |