| Parameter |
Value |
| Designation |
C/2021 C1 (Rankin) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2020-12-07T02:38:59.493120Z |
| Orbit solution date (soln_date, UTC) |
2023-05-18T19:12:34Z |
| Obs used |
164 |
| NEO |
- |
| M1 |
11.100 |
| K1 |
11.250 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-02-11T10:37:59.865600Z |
| Discovery magnitude (MPC) |
19.74 G |
| Discovery observatory (MPC) |
G96 · Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-03-26.0000000 |
| e |
0.99961692 |
| q (au) |
3.481288 |
| a (au) |
9087.668673 |
| i (deg) |
143.038610 |
| Ω (om, deg) |
186.891902 |
| ω (w, deg) |
336.306876 |
| M (ma, deg) |
0.000124 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.324 + 4.761\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.324 |
| n |
4.761 |
| gf |
1.000 |
| gb |
-0.609 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
05:24:24.52 |
+57:57:47.4 |
HIP 25197 |
26.23 |
| 2026-05-12 12:00 |
05:24:34.38 |
+57:57:15.4 |
HIP 25197 |
26.14 |
| 2026-05-13 00:00 |
05:24:44.30 |
+57:56:43.8 |
HIP 25197 |
26.13 |
| 2026-05-13 12:00 |
05:24:54.26 |
+57:56:12.8 |
HIP 25197 |
26.21 |
| 2026-05-14 00:00 |
05:25:04.27 |
+57:55:42.2 |
HIP 25197 |
26.38 |
| 2026-05-14 12:00 |
05:25:14.32 |
+57:55:12.1 |
HIP 25197 |
26.64 |
| 2026-05-15 00:00 |
05:25:24.43 |
+57:54:42.5 |
HIP 25197 |
26.98 |
| 2026-05-15 12:00 |
05:25:34.57 |
+57:54:13.3 |
HIP 25197 |
27.40 |
| 2026-05-16 00:00 |
05:25:44.76 |
+57:53:44.7 |
HIP 25474 |
27.01 |
| 2026-05-16 12:00 |
05:25:55.00 |
+57:53:16.5 |
HIP 25474 |
26.14 |
| 2026-05-17 00:00 |
05:26:05.28 |
+57:52:48.9 |
HIP 25474 |
25.34 |
| 2026-05-17 12:00 |
05:26:15.59 |
+57:52:21.7 |
HIP 25474 |
24.59 |
| 2026-05-18 00:00 |
05:26:25.95 |
+57:51:55.0 |
HIP 25474 |
23.92 |
| 2026-05-18 12:00 |
05:26:36.35 |
+57:51:28.8 |
HIP 25474 |
23.33 |
| 2026-05-19 00:00 |
05:26:46.79 |
+57:51:03.1 |
HIP 25474 |
22.83 |
| 2026-05-19 12:00 |
05:26:57.27 |
+57:50:37.8 |
HIP 25474 |
22.41 |
| 2026-05-20 00:00 |
05:27:07.78 |
+57:50:13.1 |
HIP 25474 |
22.10 |
| 2026-05-20 12:00 |
05:27:18.33 |
+57:49:48.9 |
HIP 25474 |
21.89 |
| 2026-05-21 00:00 |
05:27:28.92 |
+57:49:25.1 |
HIP 25474 |
21.78 |
| 2026-05-21 12:00 |
05:27:39.54 |
+57:49:01.8 |
HIP 25474 |
21.78 |
| 2026-05-22 00:00 |
05:27:50.19 |
+57:48:39.0 |
HIP 25474 |
21.89 |
| 2026-05-22 12:00 |
05:28:00.88 |
+57:48:16.7 |
HIP 25474 |
22.11 |
| 2026-05-23 00:00 |
05:28:11.59 |
+57:47:54.9 |
HIP 25474 |
22.44 |
| 2026-05-23 12:00 |
05:28:22.34 |
+57:47:33.5 |
HIP 25474 |
22.86 |
| 2026-05-24 00:00 |
05:28:33.12 |
+57:47:12.7 |
HIP 25474 |
23.38 |
| 2026-05-24 12:00 |
05:28:43.94 |
+57:46:52.3 |
HIP 25474 |
23.99 |
| 2026-05-25 00:00 |
05:28:54.77 |
+57:46:32.4 |
HIP 25474 |
24.68 |
| 2026-05-25 12:00 |
05:29:05.64 |
+57:46:13.0 |
HIP 25474 |
25.45 |
| 2026-05-26 00:00 |
05:29:16.54 |
+57:45:54.1 |
HIP 25474 |
26.29 |
| 2026-05-26 12:00 |
05:29:27.46 |
+57:45:35.7 |
HIP 25474 |
27.20 |
| 2026-05-27 00:00 |
05:29:38.41 |
+57:45:17.7 |
HIP 25474 |
28.16 |
| 2026-05-27 12:00 |
05:29:49.38 |
+57:45:00.2 |
HIP 25474 |
29.17 |
| 2026-05-28 00:00 |
05:30:00.38 |
+57:44:43.2 |
HIP 25474 |
30.24 |
| 2026-05-28 12:00 |
05:30:11.40 |
+57:44:26.7 |
HIP 25474 |
31.34 |
| 2026-05-29 00:00 |
05:30:22.44 |
+57:44:10.7 |
HIP 25474 |
32.49 |
| 2026-05-29 12:00 |
05:30:33.51 |
+57:43:55.1 |
HIP 26147 |
32.21 |
| 2026-05-30 00:00 |
05:30:44.60 |
+57:43:40.1 |
HIP 26147 |
30.85 |
| 2026-05-30 12:00 |
05:30:55.71 |
+57:43:25.5 |
HIP 26147 |
29.48 |
| 2026-05-31 00:00 |
05:31:06.84 |
+57:43:11.4 |
HIP 26147 |
28.13 |
| 2026-05-31 12:00 |
05:31:17.99 |
+57:42:57.7 |
HIP 26147 |
26.79 |
| 2026-06-01 00:00 |
05:31:29.16 |
+57:42:44.6 |
HIP 26147 |
25.46 |
| 2026-06-01 12:00 |
05:31:40.35 |
+57:42:31.9 |
HIP 26147 |
24.15 |
| 2026-06-02 00:00 |
05:31:51.55 |
+57:42:19.7 |
HIP 26147 |
22.85 |