C/2021 F1 (Lemmon-PANSTARRS)
| 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) |
| 2026-02-03 00:00 |
13:25:19.35 |
-76:15:01.3 |
HIP 65374 |
19.89 |
| 2026-02-03 12:00 |
13:25:05.80 |
-76:16:37.8 |
HIP 65053 |
19.71 |
| 2026-02-04 00:00 |
13:24:51.90 |
-76:18:13.7 |
HIP 65053 |
18.30 |
| 2026-02-04 12:00 |
13:24:37.65 |
-76:19:48.9 |
HIP 65053 |
16.95 |
| 2026-02-05 00:00 |
13:24:23.05 |
-76:21:23.6 |
HIP 65053 |
15.67 |
| 2026-02-05 12:00 |
13:24:08.10 |
-76:22:57.6 |
HIP 65053 |
14.48 |
| 2026-02-06 00:00 |
13:23:52.80 |
-76:24:31.0 |
HIP 65053 |
13.42 |
| 2026-02-06 12:00 |
13:23:37.14 |
-76:26:03.7 |
HIP 65053 |
12.51 |
| 2026-02-07 00:00 |
13:23:21.13 |
-76:27:35.8 |
HIP 65053 |
11.78 |
| 2026-02-07 12:00 |
13:23:04.77 |
-76:29:07.1 |
HIP 65053 |
11.28 |
| 2026-02-08 00:00 |
13:22:48.05 |
-76:30:37.8 |
HIP 65053 |
11.02 |
| 2026-02-08 12:00 |
13:22:30.98 |
-76:32:07.8 |
HIP 65053 |
11.04 |
| 2026-02-09 00:00 |
13:22:13.56 |
-76:33:37.0 |
HIP 65053 |
11.33 |
| 2026-02-09 12:00 |
13:21:55.79 |
-76:35:05.5 |
HIP 65053 |
11.87 |
| 2026-02-10 00:00 |
13:21:37.65 |
-76:36:33.3 |
HIP 65053 |
12.63 |
| 2026-02-10 12:00 |
13:21:19.17 |
-76:38:00.3 |
HIP 65053 |
13.57 |
| 2026-02-11 00:00 |
13:21:00.33 |
-76:39:26.6 |
HIP 65053 |
14.66 |
| 2026-02-11 12:00 |
13:20:41.14 |
-76:40:52.1 |
HIP 65053 |
15.86 |
| 2026-02-12 00:00 |
13:20:21.60 |
-76:42:16.8 |
HIP 65053 |
17.16 |
| 2026-02-12 12:00 |
13:20:01.70 |
-76:43:40.6 |
HIP 65053 |
18.53 |
| 2026-02-13 00:00 |
13:19:41.45 |
-76:45:03.7 |
HIP 65053 |
19.96 |
| 2026-02-13 12:00 |
13:19:20.85 |
-76:46:25.9 |
HIP 65053 |
21.43 |
| 2026-02-14 00:00 |
13:18:59.90 |
-76:47:47.3 |
HIP 65053 |
22.94 |
| 2026-02-14 12:00 |
13:18:38.60 |
-76:49:07.8 |
HIP 65053 |
24.49 |
| 2026-02-15 00:00 |
13:18:16.95 |
-76:50:27.5 |
HIP 65053 |
26.06 |
| 2026-02-15 12:00 |
13:17:54.95 |
-76:51:46.2 |
HIP 65053 |
27.65 |
| 2026-02-16 00:00 |
13:17:32.60 |
-76:53:04.1 |
HIP 65053 |
29.26 |
| 2026-02-16 12:00 |
13:17:09.91 |
-76:54:21.1 |
HIP 65053 |
30.89 |
| 2026-02-17 00:00 |
13:16:46.87 |
-76:55:37.1 |
HIP 65053 |
32.53 |
| 2026-02-17 12:00 |
13:16:23.49 |
-76:56:52.2 |
HIP 64554 |
31.77 |
| 2026-02-18 00:00 |
13:15:59.77 |
-76:58:06.4 |
HIP 64554 |
30.25 |
| 2026-02-18 12:00 |
13:15:35.71 |
-76:59:19.6 |
HIP 64554 |
28.78 |
| 2026-02-19 00:00 |
13:15:11.31 |
-77:00:31.8 |
HIP 64554 |
27.35 |
| 2026-02-19 12:00 |
13:14:46.57 |
-77:01:43.1 |
HIP 64554 |
25.99 |
| 2026-02-20 00:00 |
13:14:21.50 |
-77:02:53.3 |
HIP 64554 |
24.71 |
| 2026-02-20 12:00 |
13:13:56.10 |
-77:04:02.5 |
HIP 64554 |
23.51 |
| 2026-02-21 00:00 |
13:13:30.36 |
-77:05:10.7 |
HIP 64554 |
22.41 |
| 2026-02-21 12:00 |
13:13:04.30 |
-77:06:17.9 |
HIP 64091 |
20.72 |
| 2026-02-22 00:00 |
13:12:37.92 |
-77:07:24.0 |
HIP 64091 |
18.88 |
| 2026-02-22 12:00 |
13:12:11.21 |
-77:08:29.1 |
HIP 64091 |
17.04 |
| 2026-02-23 00:00 |
13:11:44.18 |
-77:09:33.1 |
HIP 64091 |
15.20 |
| 2026-02-23 12:00 |
13:11:16.83 |
-77:10:36.0 |
HIP 64091 |
13.36 |
| 2026-02-24 00:00 |
13:10:49.17 |
-77:11:37.9 |
HIP 64091 |
11.51 |