| 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) |
| 2026-05-12 00:00 |
11:48:31.93 |
-75:26:14.7 |
HIP 57715 |
13.56 |
| 2026-05-12 12:00 |
11:48:14.68 |
-75:24:05.7 |
HIP 57715 |
15.97 |
| 2026-05-13 00:00 |
11:47:57.75 |
-75:21:56.1 |
HIP 57715 |
18.38 |
| 2026-05-13 12:00 |
11:47:41.14 |
-75:19:46.0 |
HIP 57715 |
20.79 |
| 2026-05-14 00:00 |
11:47:24.84 |
-75:17:35.2 |
HIP 57294 |
19.94 |
| 2026-05-14 12:00 |
11:47:08.87 |
-75:15:24.0 |
HIP 57294 |
17.53 |
| 2026-05-15 00:00 |
11:46:53.21 |
-75:13:12.1 |
HIP 57294 |
15.14 |
| 2026-05-15 12:00 |
11:46:37.86 |
-75:10:59.8 |
HIP 57294 |
12.75 |
| 2026-05-16 00:00 |
11:46:22.83 |
-75:08:46.9 |
HIP 57294 |
10.37 |
| 2026-05-16 12:00 |
11:46:08.12 |
-75:06:33.6 |
HIP 57294 |
8.02 |
| 2026-05-17 00:00 |
11:45:53.73 |
-75:04:19.7 |
HIP 57294 |
5.73 |
| 2026-05-17 12:00 |
11:45:39.64 |
-75:02:05.4 |
HIP 57294 |
3.62 |
| 2026-05-18 00:00 |
11:45:25.87 |
-74:59:50.6 |
HIP 57294 |
2.26 |
| 2026-05-18 12:00 |
11:45:12.42 |
-74:57:35.4 |
HIP 57294 |
2.98 |
| 2026-05-19 00:00 |
11:44:59.27 |
-74:55:19.8 |
HIP 57333 |
3.16 |
| 2026-05-19 12:00 |
11:44:46.44 |
-74:53:03.7 |
HIP 57333 |
2.20 |
| 2026-05-20 00:00 |
11:44:33.91 |
-74:50:47.3 |
HIP 57333 |
3.36 |
| 2026-05-20 12:00 |
11:44:21.70 |
-74:48:30.4 |
HIP 57333 |
5.42 |
| 2026-05-21 00:00 |
11:44:09.79 |
-74:46:13.2 |
HIP 57333 |
7.68 |
| 2026-05-21 12:00 |
11:43:58.18 |
-74:43:55.7 |
HIP 57333 |
10.01 |
| 2026-05-22 00:00 |
11:43:46.88 |
-74:41:37.8 |
HIP 57333 |
12.37 |
| 2026-05-22 12:00 |
11:43:35.89 |
-74:39:19.5 |
HIP 57333 |
14.75 |
| 2026-05-23 00:00 |
11:43:25.19 |
-74:37:01.0 |
HIP 57333 |
17.13 |
| 2026-05-23 12:00 |
11:43:14.80 |
-74:34:42.1 |
HIP 57333 |
19.52 |
| 2026-05-24 00:00 |
11:43:04.70 |
-74:32:22.9 |
HIP 57333 |
21.92 |
| 2026-05-24 12:00 |
11:42:54.90 |
-74:30:03.5 |
HIP 57333 |
24.31 |
| 2026-05-25 00:00 |
11:42:45.40 |
-74:27:43.8 |
HIP 57333 |
26.70 |
| 2026-05-25 12:00 |
11:42:36.19 |
-74:25:23.9 |
HIP 57333 |
29.10 |
| 2026-05-26 00:00 |
11:42:27.27 |
-74:23:03.7 |
HIP 57287 |
28.16 |
| 2026-05-26 12:00 |
11:42:18.64 |
-74:20:43.3 |
HIP 57287 |
26.20 |
| 2026-05-27 00:00 |
11:42:10.31 |
-74:18:22.6 |
HIP 57287 |
24.31 |
| 2026-05-27 12:00 |
11:42:02.26 |
-74:16:01.8 |
HIP 57287 |
22.51 |
| 2026-05-28 00:00 |
11:41:54.49 |
-74:13:40.7 |
HIP 57287 |
20.82 |
| 2026-05-28 12:00 |
11:41:47.01 |
-74:11:19.5 |
HIP 57287 |
19.27 |
| 2026-05-29 00:00 |
11:41:39.82 |
-74:08:58.1 |
HIP 57287 |
17.90 |
| 2026-05-29 12:00 |
11:41:32.90 |
-74:06:36.6 |
HIP 57287 |
16.75 |
| 2026-05-30 00:00 |
11:41:26.27 |
-74:04:14.9 |
HIP 57287 |
15.86 |
| 2026-05-30 12:00 |
11:41:19.91 |
-74:01:53.1 |
HIP 57287 |
15.29 |
| 2026-05-31 00:00 |
11:41:13.83 |
-73:59:31.1 |
HIP 56847 |
13.37 |
| 2026-05-31 12:00 |
11:41:08.02 |
-73:57:09.1 |
HIP 56847 |
11.29 |
| 2026-06-01 00:00 |
11:41:02.49 |
-73:54:46.9 |
HIP 56847 |
9.37 |
| 2026-06-01 12:00 |
11:40:57.23 |
-73:52:24.7 |
HIP 56847 |
7.74 |
| 2026-06-02 00:00 |
11:40:52.24 |
-73:50:02.3 |
HIP 56847 |
6.63 |