| 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) |
| 2026-03-26 00:00 |
05:14:32.21 |
+59:22:07.1 |
HIP 24479 |
5.46 |
| 2026-03-26 12:00 |
05:14:33.79 |
+59:20:54.2 |
HIP 24479 |
5.89 |
| 2026-03-27 00:00 |
05:14:35.50 |
+59:19:41.6 |
HIP 24479 |
6.52 |
| 2026-03-27 12:00 |
05:14:37.33 |
+59:18:29.4 |
HIP 24479 |
7.29 |
| 2026-03-28 00:00 |
05:14:39.29 |
+59:17:17.6 |
HIP 24479 |
8.15 |
| 2026-03-28 12:00 |
05:14:41.37 |
+59:16:06.0 |
HIP 24479 |
9.09 |
| 2026-03-29 00:00 |
05:14:43.58 |
+59:14:54.8 |
HIP 24479 |
10.07 |
| 2026-03-29 12:00 |
05:14:45.91 |
+59:13:44.0 |
HIP 24479 |
11.10 |
| 2026-03-30 00:00 |
05:14:48.36 |
+59:12:33.5 |
HIP 24479 |
12.14 |
| 2026-03-30 12:00 |
05:14:50.94 |
+59:11:23.4 |
HIP 24479 |
13.21 |
| 2026-03-31 00:00 |
05:14:53.63 |
+59:10:13.7 |
HIP 24479 |
14.30 |
| 2026-03-31 12:00 |
05:14:56.45 |
+59:09:04.3 |
HIP 24479 |
15.39 |
| 2026-04-01 00:00 |
05:14:59.38 |
+59:07:55.2 |
HIP 24479 |
16.49 |
| 2026-04-01 12:00 |
05:15:02.43 |
+59:06:46.6 |
HIP 24479 |
17.60 |
| 2026-04-02 00:00 |
05:15:05.60 |
+59:05:38.3 |
HIP 24479 |
18.72 |
| 2026-04-02 12:00 |
05:15:08.88 |
+59:04:30.4 |
HIP 24479 |
19.84 |
| 2026-04-03 00:00 |
05:15:12.28 |
+59:03:22.8 |
HIP 24479 |
20.96 |
| 2026-04-03 12:00 |
05:15:15.80 |
+59:02:15.7 |
HIP 24479 |
22.09 |
| 2026-04-04 00:00 |
05:15:19.43 |
+59:01:08.9 |
HIP 24479 |
23.22 |
| 2026-04-04 12:00 |
05:15:23.17 |
+59:00:02.5 |
HIP 24479 |
24.35 |
| 2026-04-05 00:00 |
05:15:27.02 |
+58:58:56.5 |
HIP 24479 |
25.48 |
| 2026-04-05 12:00 |
05:15:30.99 |
+58:57:50.9 |
HIP 24328 |
25.25 |
| 2026-04-06 00:00 |
05:15:35.07 |
+58:56:45.7 |
HIP 24328 |
24.87 |
| 2026-04-06 12:00 |
05:15:39.25 |
+58:55:40.8 |
HIP 24328 |
24.56 |
| 2026-04-07 00:00 |
05:15:43.55 |
+58:54:36.4 |
HIP 24328 |
24.32 |
| 2026-04-07 12:00 |
05:15:47.95 |
+58:53:32.4 |
HIP 24328 |
24.16 |
| 2026-04-08 00:00 |
05:15:52.46 |
+58:52:28.8 |
HIP 24328 |
24.07 |
| 2026-04-08 12:00 |
05:15:57.08 |
+58:51:25.5 |
HIP 24328 |
24.06 |
| 2026-04-09 00:00 |
05:16:01.80 |
+58:50:22.7 |
HIP 24328 |
24.13 |
| 2026-04-09 12:00 |
05:16:06.63 |
+58:49:20.3 |
HIP 24328 |
24.27 |
| 2026-04-10 00:00 |
05:16:11.56 |
+58:48:18.3 |
HIP 24328 |
24.48 |
| 2026-04-10 12:00 |
05:16:16.60 |
+58:47:16.8 |
HIP 24328 |
24.77 |
| 2026-04-11 00:00 |
05:16:21.74 |
+58:46:15.6 |
HIP 24328 |
25.14 |
| 2026-04-11 12:00 |
05:16:26.98 |
+58:45:14.9 |
HIP 24328 |
25.56 |
| 2026-04-12 00:00 |
05:16:32.32 |
+58:44:14.6 |
HIP 24328 |
26.06 |
| 2026-04-12 12:00 |
05:16:37.76 |
+58:43:14.7 |
HIP 24328 |
26.61 |
| 2026-04-13 00:00 |
05:16:43.31 |
+58:42:15.2 |
HIP 24328 |
27.23 |
| 2026-04-13 12:00 |
05:16:48.95 |
+58:41:16.2 |
HIP 24328 |
27.89 |
| 2026-04-14 00:00 |
05:16:54.68 |
+58:40:17.6 |
HIP 24328 |
28.61 |
| 2026-04-14 12:00 |
05:17:00.52 |
+58:39:19.4 |
HIP 24328 |
29.38 |
| 2026-04-15 00:00 |
05:17:06.45 |
+58:38:21.7 |
HIP 24328 |
30.18 |
| 2026-04-15 12:00 |
05:17:12.48 |
+58:37:24.4 |
HIP 24328 |
31.03 |
| 2026-04-16 00:00 |
05:17:18.60 |
+58:36:27.5 |
HIP 24328 |
31.92 |