C/2021 C1 (Rankin)
| 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) |
| 2026-02-03 00:00 |
05:25:06.72 |
+61:38:06.8 |
HIP 25393 |
10.55 |
| 2026-02-03 12:00 |
05:24:52.19 |
+61:36:52.4 |
HIP 25393 |
12.55 |
| 2026-02-04 00:00 |
05:24:37.82 |
+61:35:37.6 |
HIP 25328 |
14.19 |
| 2026-02-04 12:00 |
05:24:23.61 |
+61:34:22.4 |
HIP 25150 |
15.00 |
| 2026-02-05 00:00 |
05:24:09.56 |
+61:33:06.8 |
HIP 25150 |
14.88 |
| 2026-02-05 12:00 |
05:23:55.69 |
+61:31:50.9 |
HIP 25150 |
15.07 |
| 2026-02-06 00:00 |
05:23:41.97 |
+61:30:34.6 |
HIP 25150 |
15.54 |
| 2026-02-06 12:00 |
05:23:28.43 |
+61:29:17.9 |
HIP 25150 |
16.28 |
| 2026-02-07 00:00 |
05:23:15.05 |
+61:28:00.9 |
HIP 25150 |
17.24 |
| 2026-02-07 12:00 |
05:23:01.83 |
+61:26:43.5 |
HIP 25150 |
18.38 |
| 2026-02-08 00:00 |
05:22:48.79 |
+61:25:25.8 |
HIP 25150 |
19.68 |
| 2026-02-08 12:00 |
05:22:35.91 |
+61:24:07.8 |
HIP 25150 |
21.09 |
| 2026-02-09 00:00 |
05:22:23.20 |
+61:22:49.5 |
HIP 25150 |
22.59 |
| 2026-02-09 12:00 |
05:22:10.66 |
+61:21:30.9 |
HIP 25150 |
24.17 |
| 2026-02-10 00:00 |
05:21:58.29 |
+61:20:12.0 |
HIP 25150 |
25.80 |
| 2026-02-10 12:00 |
05:21:46.09 |
+61:18:52.9 |
HIP 24726 |
26.57 |
| 2026-02-11 00:00 |
05:21:34.05 |
+61:17:33.4 |
HIP 24726 |
24.90 |
| 2026-02-11 12:00 |
05:21:22.19 |
+61:16:13.7 |
HIP 24726 |
23.29 |
| 2026-02-12 00:00 |
05:21:10.50 |
+61:14:53.8 |
HIP 24726 |
21.74 |
| 2026-02-12 12:00 |
05:20:58.97 |
+61:13:33.6 |
HIP 24726 |
20.29 |
| 2026-02-13 00:00 |
05:20:47.62 |
+61:12:13.1 |
HIP 24726 |
18.94 |
| 2026-02-13 12:00 |
05:20:36.44 |
+61:10:52.5 |
HIP 24726 |
17.71 |
| 2026-02-14 00:00 |
05:20:25.42 |
+61:09:31.6 |
HIP 24726 |
16.63 |
| 2026-02-14 12:00 |
05:20:14.58 |
+61:08:10.5 |
HIP 24726 |
15.72 |
| 2026-02-15 00:00 |
05:20:03.91 |
+61:06:49.3 |
HIP 24726 |
15.01 |
| 2026-02-15 12:00 |
05:19:53.41 |
+61:05:27.8 |
HIP 24726 |
14.53 |
| 2026-02-16 00:00 |
05:19:43.08 |
+61:04:06.2 |
HIP 24726 |
14.29 |
| 2026-02-16 12:00 |
05:19:32.93 |
+61:02:44.4 |
HIP 24726 |
14.30 |
| 2026-02-17 00:00 |
05:19:22.94 |
+61:01:22.4 |
HIP 24726 |
14.56 |
| 2026-02-17 12:00 |
05:19:13.12 |
+61:00:00.3 |
HIP 24726 |
15.04 |
| 2026-02-18 00:00 |
05:19:03.48 |
+60:58:38.0 |
HIP 24726 |
15.74 |
| 2026-02-18 12:00 |
05:18:54.01 |
+60:57:15.6 |
HIP 24726 |
16.60 |
| 2026-02-19 00:00 |
05:18:44.70 |
+60:55:53.1 |
HIP 24726 |
17.61 |
| 2026-02-19 12:00 |
05:18:35.57 |
+60:54:30.5 |
HIP 24726 |
18.74 |
| 2026-02-20 00:00 |
05:18:26.61 |
+60:53:07.8 |
HIP 24525 |
19.94 |
| 2026-02-20 12:00 |
05:18:17.82 |
+60:51:45.0 |
HIP 24525 |
18.95 |
| 2026-02-21 00:00 |
05:18:09.20 |
+60:50:22.1 |
HIP 24525 |
18.10 |
| 2026-02-21 12:00 |
05:18:00.75 |
+60:48:59.1 |
HIP 24525 |
17.40 |
| 2026-02-22 00:00 |
05:17:52.47 |
+60:47:36.0 |
HIP 24525 |
16.86 |
| 2026-02-22 12:00 |
05:17:44.36 |
+60:46:12.9 |
HIP 24525 |
16.50 |
| 2026-02-23 00:00 |
05:17:36.41 |
+60:44:49.7 |
HIP 24525 |
16.33 |
| 2026-02-23 12:00 |
05:17:28.64 |
+60:43:26.5 |
HIP 24525 |
16.34 |
| 2026-02-24 00:00 |
05:17:21.03 |
+60:42:03.3 |
HIP 24525 |
16.55 |