C/2021 C6 (Lemmon)
| Parameter |
Value |
| Designation |
C/2021 C6 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-11-13T08:19:46.225920Z |
| Orbit solution date (soln_date, UTC) |
2022-12-28T10:16:54Z |
| Obs used |
199 |
| NEO |
- |
| M1 |
15.600 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-02-07T10:22:20.006400Z |
| Discovery magnitude (MPC) |
20.86 G |
| Discovery observatory (MPC) |
G96 · Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-09-15.0000000 |
| e |
1.00185407 |
| q (au) |
3.271189 |
| a (au) |
-1764.328257 |
| i (deg) |
164.625857 |
| Ω (om, deg) |
332.155949 |
| ω (w, deg) |
203.567737 |
| M (ma, deg) |
-0.000789 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.001 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.001 |
| n |
2.000 |
| gf |
0.931 |
| gb |
-0.889 |
| k |
1.000 |
| 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 |
| 2021-01-23 |
2021-11-09 |
-4.1916 |
+2.446 |
| 2021-11-28 |
2022-12-15 |
+13.4351 |
-7.126 |
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 |
00:36:45.54 |
-05:55:07.1 |
HIP 2919 |
11.89 |
| 2026-02-03 12:00 |
00:36:48.61 |
-05:54:21.5 |
HIP 2919 |
12.48 |
| 2026-02-04 00:00 |
00:36:51.74 |
-05:53:35.7 |
HIP 2919 |
13.13 |
| 2026-02-04 12:00 |
00:36:54.93 |
-05:52:49.8 |
HIP 2919 |
13.83 |
| 2026-02-05 00:00 |
00:36:58.17 |
-05:52:03.6 |
HIP 2919 |
14.59 |
| 2026-02-05 12:00 |
00:37:01.47 |
-05:51:17.2 |
HIP 2919 |
15.40 |
| 2026-02-06 00:00 |
00:37:04.82 |
-05:50:30.7 |
HIP 2980 |
15.98 |
| 2026-02-06 12:00 |
00:37:08.23 |
-05:49:43.9 |
HIP 2980 |
15.79 |
| 2026-02-07 00:00 |
00:37:11.70 |
-05:48:57.0 |
HIP 2980 |
15.67 |
| 2026-02-07 12:00 |
00:37:15.22 |
-05:48:09.9 |
HIP 2980 |
15.64 |
| 2026-02-08 00:00 |
00:37:18.79 |
-05:47:22.6 |
HIP 2980 |
15.68 |
| 2026-02-08 12:00 |
00:37:22.41 |
-05:46:35.1 |
HIP 2980 |
15.81 |
| 2026-02-09 00:00 |
00:37:26.09 |
-05:45:47.5 |
HIP 2980 |
16.03 |
| 2026-02-09 12:00 |
00:37:29.82 |
-05:44:59.7 |
HIP 2980 |
16.33 |
| 2026-02-10 00:00 |
00:37:33.60 |
-05:44:11.8 |
HIP 2980 |
16.71 |
| 2026-02-10 12:00 |
00:37:37.43 |
-05:43:23.7 |
HIP 2980 |
17.18 |
| 2026-02-11 00:00 |
00:37:41.31 |
-05:42:35.4 |
HIP 2980 |
17.71 |
| 2026-02-11 12:00 |
00:37:45.25 |
-05:41:47.0 |
HIP 2980 |
18.32 |
| 2026-02-12 00:00 |
00:37:49.23 |
-05:40:58.5 |
HIP 2980 |
19.00 |
| 2026-02-12 12:00 |
00:37:53.26 |
-05:40:09.8 |
HIP 2980 |
19.73 |
| 2026-02-13 00:00 |
00:37:57.34 |
-05:39:21.0 |
HIP 2980 |
20.53 |
| 2026-02-13 12:00 |
00:38:01.47 |
-05:38:32.0 |
HIP 2980 |
21.37 |
| 2026-02-14 00:00 |
00:38:05.65 |
-05:37:42.9 |
HIP 2980 |
22.27 |
| 2026-02-14 12:00 |
00:38:09.87 |
-05:36:53.7 |
HIP 2980 |
23.21 |
| 2026-02-15 00:00 |
00:38:14.14 |
-05:36:04.4 |
HIP 2980 |
24.19 |
| 2026-02-15 12:00 |
00:38:18.46 |
-05:35:14.9 |
HIP 2980 |
25.21 |
| 2026-02-16 00:00 |
00:38:22.82 |
-05:34:25.3 |
HIP 2980 |
26.26 |
| 2026-02-16 12:00 |
00:38:27.23 |
-05:33:35.7 |
HIP 2980 |
27.35 |
| 2026-02-17 00:00 |
00:38:31.68 |
-05:32:45.9 |
HIP 2980 |
28.46 |
| 2026-02-17 12:00 |
00:38:36.17 |
-05:31:56.0 |
HIP 2980 |
29.60 |
| 2026-02-18 00:00 |
00:38:40.71 |
-05:31:06.0 |
HIP 2980 |
30.77 |
| 2026-02-18 12:00 |
00:38:45.30 |
-05:30:15.9 |
HIP 2980 |
31.97 |
| 2026-02-19 00:00 |
00:38:49.92 |
-05:29:25.7 |
HIP 2980 |
33.18 |
| 2026-02-19 12:00 |
00:38:54.59 |
-05:28:35.5 |
HIP 2980 |
34.42 |
| 2026-02-20 00:00 |
00:38:59.29 |
-05:27:45.1 |
HIP 2980 |
35.68 |
| 2026-02-20 12:00 |
00:39:04.04 |
-05:26:54.7 |
HIP 2980 |
36.96 |
| 2026-02-21 00:00 |
00:39:08.83 |
-05:26:04.2 |
HIP 2980 |
38.25 |
| 2026-02-21 12:00 |
00:39:13.66 |
-05:25:13.7 |
HIP 2980 |
39.57 |
| 2026-02-22 00:00 |
00:39:18.53 |
-05:24:23.0 |
HIP 2980 |
40.90 |
| 2026-02-22 12:00 |
00:39:23.43 |
-05:23:32.3 |
HIP 2980 |
42.24 |
| 2026-02-23 00:00 |
00:39:28.38 |
-05:22:41.6 |
HIP 2980 |
43.60 |
| 2026-02-23 12:00 |
00:39:33.36 |
-05:21:50.8 |
HIP 2980 |
44.97 |
| 2026-02-24 00:00 |
00:39:38.37 |
-05:21:00.0 |
HIP 2980 |
46.36 |