| Parameter |
Value |
| Designation |
C/2020 U3 (Rankin) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-02-05T23:23:23.781120Z |
| Orbit solution date (soln_date, UTC) |
2023-04-24T19:06:41Z |
| Obs used |
178 |
| NEO |
- |
| M1 |
9.700 |
| K1 |
22.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2020-10-22T03:37:43.852800Z |
| Discovery magnitude (MPC) |
20.14 G |
| Discovery observatory (MPC) |
G96 · University of Arizona Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2020-11-22.0000000 |
| e |
0.96479330 |
| q (au) |
2.276177 |
| a (au) |
64.651799 |
| i (deg) |
30.176991 |
| Ω (om, deg) |
282.679092 |
| ω (w, deg) |
124.262013 |
| M (ma, deg) |
359.855954 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.589 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.589 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
1.000 |
| 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 |
| 2020-07-21 |
2021-02-05 |
+3.5360 |
-1.291 |
| 2021-02-07 |
2021-10-31 |
+2.0235 |
-1.913 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
11:06:14.33 |
-25:35:34.0 |
HIP 54215 |
35.60 |
| 2026-07-29 12:00 |
11:06:21.37 |
-25:35:36.0 |
HIP 54215 |
36.07 |
| 2026-07-30 00:00 |
11:06:28.44 |
-25:35:38.6 |
HIP 54215 |
36.61 |
| 2026-07-30 12:00 |
11:06:35.55 |
-25:35:41.7 |
HIP 54215 |
37.23 |
| 2026-07-31 00:00 |
11:06:42.69 |
-25:35:45.4 |
HIP 54215 |
37.92 |
| 2026-07-31 12:00 |
11:06:49.86 |
-25:35:49.7 |
HIP 54215 |
38.68 |
| 2026-08-01 00:00 |
11:06:57.07 |
-25:35:54.5 |
HIP 54446 |
38.64 |
| 2026-08-01 12:00 |
11:07:04.30 |
-25:35:59.9 |
HIP 54446 |
37.76 |
| 2026-08-02 00:00 |
11:07:11.57 |
-25:36:05.8 |
HIP 54446 |
36.93 |
| 2026-08-02 12:00 |
11:07:18.87 |
-25:36:12.3 |
HIP 54446 |
36.14 |
| 2026-08-03 00:00 |
11:07:26.20 |
-25:36:19.3 |
HIP 54446 |
35.40 |
| 2026-08-03 12:00 |
11:07:33.55 |
-25:36:26.8 |
HIP 54576 |
34.15 |
| 2026-08-04 00:00 |
11:07:40.94 |
-25:36:35.0 |
HIP 54576 |
32.48 |
| 2026-08-04 12:00 |
11:07:48.36 |
-25:36:43.6 |
HIP 54576 |
30.81 |
| 2026-08-05 00:00 |
11:07:55.80 |
-25:36:52.8 |
HIP 54576 |
29.13 |
| 2026-08-05 12:00 |
11:08:03.28 |
-25:37:02.6 |
HIP 54576 |
27.45 |
| 2026-08-06 00:00 |
11:08:10.78 |
-25:37:12.9 |
HIP 54576 |
25.76 |
| 2026-08-06 12:00 |
11:08:18.31 |
-25:37:23.8 |
HIP 54576 |
24.07 |
| 2026-08-07 00:00 |
11:08:25.87 |
-25:37:35.2 |
HIP 54576 |
22.38 |
| 2026-08-07 12:00 |
11:08:33.46 |
-25:37:47.1 |
HIP 54576 |
20.68 |
| 2026-08-08 00:00 |
11:08:41.07 |
-25:37:59.7 |
HIP 54576 |
18.99 |
| 2026-08-08 12:00 |
11:08:48.71 |
-25:38:12.7 |
HIP 54576 |
17.29 |
| 2026-08-09 00:00 |
11:08:56.38 |
-25:38:26.3 |
HIP 54576 |
15.60 |
| 2026-08-09 12:00 |
11:09:04.07 |
-25:38:40.4 |
HIP 54576 |
13.92 |
| 2026-08-10 00:00 |
11:09:11.78 |
-25:38:55.1 |
HIP 54576 |
12.25 |
| 2026-08-10 12:00 |
11:09:19.53 |
-25:39:10.3 |
HIP 54576 |
10.61 |
| 2026-08-11 00:00 |
11:09:27.29 |
-25:39:26.1 |
HIP 54576 |
9.01 |
| 2026-08-11 12:00 |
11:09:35.08 |
-25:39:42.4 |
HIP 54576 |
7.49 |
| 2026-08-12 00:00 |
11:09:42.89 |
-25:39:59.2 |
HIP 54576 |
6.11 |
| 2026-08-12 12:00 |
11:09:50.73 |
-25:40:16.6 |
HIP 54576 |
5.00 |
| 2026-08-13 00:00 |
11:09:58.59 |
-25:40:34.5 |
HIP 54576 |
4.37 |
| 2026-08-13 12:00 |
11:10:06.47 |
-25:40:53.0 |
HIP 54576 |
4.44 |
| 2026-08-14 00:00 |
11:10:14.37 |
-25:41:12.0 |
HIP 54576 |
5.20 |
| 2026-08-14 12:00 |
11:10:22.29 |
-25:41:31.5 |
HIP 54576 |
6.40 |
| 2026-08-15 00:00 |
11:10:30.24 |
-25:41:51.5 |
HIP 54576 |
7.84 |
| 2026-08-15 12:00 |
11:10:38.20 |
-25:42:12.1 |
HIP 54576 |
9.43 |
| 2026-08-16 00:00 |
11:10:46.19 |
-25:42:33.2 |
HIP 54576 |
11.10 |
| 2026-08-16 12:00 |
11:10:54.19 |
-25:42:54.8 |
HIP 54576 |
12.83 |
| 2026-08-17 00:00 |
11:11:02.21 |
-25:43:17.0 |
HIP 54576 |
14.59 |
| 2026-08-17 12:00 |
11:11:10.25 |
-25:43:39.7 |
HIP 54576 |
16.37 |
| 2026-08-18 00:00 |
11:11:18.31 |
-25:44:02.9 |
HIP 54576 |
18.18 |
| 2026-08-18 12:00 |
11:11:26.39 |
-25:44:26.6 |
HIP 54605 |
19.63 |
| 2026-08-19 00:00 |
11:11:34.49 |
-25:44:50.8 |
HIP 54605 |
20.52 |