| 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 · University of Arizona 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 |
0.961 |
| 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) |
| 2026-07-29 00:00 |
05:52:00.41 |
+58:09:21.0 |
HIP 27838 |
16.15 |
| 2026-07-29 12:00 |
05:52:08.80 |
+58:10:00.0 |
HIP 27838 |
15.89 |
| 2026-07-30 00:00 |
05:52:17.13 |
+58:10:39.4 |
HIP 27838 |
15.73 |
| 2026-07-30 12:00 |
05:52:25.39 |
+58:11:19.2 |
HIP 27903 |
14.79 |
| 2026-07-31 00:00 |
05:52:33.59 |
+58:11:59.3 |
HIP 27903 |
13.63 |
| 2026-07-31 12:00 |
05:52:41.72 |
+58:12:39.8 |
HIP 27903 |
12.49 |
| 2026-08-01 00:00 |
05:52:49.78 |
+58:13:20.7 |
HIP 27903 |
11.40 |
| 2026-08-01 12:00 |
05:52:57.77 |
+58:14:02.0 |
HIP 27903 |
10.34 |
| 2026-08-02 00:00 |
05:53:05.69 |
+58:14:43.7 |
HIP 27903 |
9.35 |
| 2026-08-02 12:00 |
05:53:13.54 |
+58:15:25.8 |
HIP 27903 |
8.45 |
| 2026-08-03 00:00 |
05:53:21.32 |
+58:16:08.2 |
HIP 27903 |
7.65 |
| 2026-08-03 12:00 |
05:53:29.02 |
+58:16:51.0 |
HIP 27903 |
6.99 |
| 2026-08-04 00:00 |
05:53:36.66 |
+58:17:34.2 |
HIP 27903 |
6.52 |
| 2026-08-04 12:00 |
05:53:44.22 |
+58:18:17.8 |
HIP 27903 |
6.27 |
| 2026-08-05 00:00 |
05:53:51.70 |
+58:19:01.7 |
HIP 27903 |
6.27 |
| 2026-08-05 12:00 |
05:53:59.11 |
+58:19:46.0 |
HIP 27903 |
6.51 |
| 2026-08-06 00:00 |
05:54:06.45 |
+58:20:30.7 |
HIP 27903 |
6.97 |
| 2026-08-06 12:00 |
05:54:13.71 |
+58:21:15.7 |
HIP 27903 |
7.61 |
| 2026-08-07 00:00 |
05:54:20.89 |
+58:22:01.1 |
HIP 27903 |
8.38 |
| 2026-08-07 12:00 |
05:54:28.00 |
+58:22:46.9 |
HIP 27903 |
9.25 |
| 2026-08-08 00:00 |
05:54:35.02 |
+58:23:33.0 |
HIP 27903 |
10.19 |
| 2026-08-08 12:00 |
05:54:41.97 |
+58:24:19.5 |
HIP 27903 |
11.18 |
| 2026-08-09 00:00 |
05:54:48.83 |
+58:25:06.4 |
HIP 27903 |
12.22 |
| 2026-08-09 12:00 |
05:54:55.62 |
+58:25:53.6 |
HIP 27903 |
13.28 |
| 2026-08-10 00:00 |
05:55:02.32 |
+58:26:41.2 |
HIP 27903 |
14.36 |
| 2026-08-10 12:00 |
05:55:08.94 |
+58:27:29.1 |
HIP 27903 |
15.45 |
| 2026-08-11 00:00 |
05:55:15.48 |
+58:28:17.4 |
HIP 27903 |
16.56 |
| 2026-08-11 12:00 |
05:55:21.93 |
+58:29:06.0 |
HIP 27903 |
17.68 |
| 2026-08-12 00:00 |
05:55:28.30 |
+58:29:55.0 |
HIP 27903 |
18.80 |
| 2026-08-12 12:00 |
05:55:34.58 |
+58:30:44.3 |
HIP 27903 |
19.92 |
| 2026-08-13 00:00 |
05:55:40.77 |
+58:31:34.0 |
HIP 27903 |
21.05 |
| 2026-08-13 12:00 |
05:55:46.88 |
+58:32:24.0 |
HIP 27903 |
22.18 |
| 2026-08-14 00:00 |
05:55:52.89 |
+58:33:14.3 |
HIP 27903 |
23.31 |
| 2026-08-14 12:00 |
05:55:58.82 |
+58:34:05.0 |
HIP 27903 |
24.44 |
| 2026-08-15 00:00 |
05:56:04.66 |
+58:34:56.0 |
HIP 27903 |
25.57 |
| 2026-08-15 12:00 |
05:56:10.41 |
+58:35:47.3 |
HIP 27903 |
26.70 |
| 2026-08-16 00:00 |
05:56:16.07 |
+58:36:39.0 |
HIP 28368 |
26.29 |
| 2026-08-16 12:00 |
05:56:21.63 |
+58:37:31.0 |
HIP 28368 |
25.61 |
| 2026-08-17 00:00 |
05:56:27.10 |
+58:38:23.3 |
HIP 28368 |
24.97 |
| 2026-08-17 12:00 |
05:56:32.48 |
+58:39:15.9 |
HIP 28368 |
24.39 |
| 2026-08-18 00:00 |
05:56:37.77 |
+58:40:08.9 |
HIP 28368 |
23.86 |
| 2026-08-18 12:00 |
05:56:42.96 |
+58:41:02.1 |
HIP 28368 |
23.38 |
| 2026-08-19 00:00 |
05:56:48.06 |
+58:41:55.7 |
HIP 28368 |
22.96 |