| Parameter |
Value |
| Designation |
C/2021 C3 (Catalina) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-02-12T10:38:30.753600Z |
| Orbit solution date (soln_date, UTC) |
2024-06-21T13:42:16Z |
| Obs used |
363 |
| NEO |
- |
| M1 |
16.100 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-02-07T11:02:01.017600Z |
| Discovery magnitude (MPC) |
19.15 G |
| Discovery observatory (MPC) |
703 · Catalina Sky Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-03-28.0000000 |
| e |
0.96405640 |
| q (au) |
2.276500 |
| a (au) |
63.335351 |
| i (deg) |
122.161615 |
| Ω (om, deg) |
181.919832 |
| ω (w, deg) |
357.151666 |
| M (ma, deg) |
0.085170 |
Magnitude
Scatter + Global Linear
$$
M_a = (17.520 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
17.520 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.650 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2021-02-13 |
2021-06-09 |
-16.5522 |
+5.942 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
00:42:35.65 |
+44:45:48.2 |
HIP 3252 |
12.63 |
| 2026-03-26 12:00 |
00:42:45.50 |
+44:45:58.3 |
HIP 3252 |
14.30 |
| 2026-03-27 00:00 |
00:42:55.35 |
+44:46:09.0 |
HIP 3252 |
15.98 |
| 2026-03-27 12:00 |
00:43:05.20 |
+44:46:20.4 |
HIP 3252 |
17.68 |
| 2026-03-28 00:00 |
00:43:15.05 |
+44:46:32.4 |
HIP 3252 |
19.38 |
| 2026-03-28 12:00 |
00:43:24.90 |
+44:46:45.0 |
HIP 3252 |
21.10 |
| 2026-03-29 00:00 |
00:43:34.76 |
+44:46:58.2 |
HIP 3252 |
22.82 |
| 2026-03-29 12:00 |
00:43:44.61 |
+44:47:12.0 |
HIP 3252 |
24.54 |
| 2026-03-30 00:00 |
00:43:54.46 |
+44:47:26.5 |
HIP 3604 |
24.54 |
| 2026-03-30 12:00 |
00:44:04.31 |
+44:47:41.5 |
HIP 3604 |
22.78 |
| 2026-03-31 00:00 |
00:44:14.16 |
+44:47:57.1 |
HIP 3604 |
21.02 |
| 2026-03-31 12:00 |
00:44:24.00 |
+44:48:13.4 |
HIP 3604 |
19.25 |
| 2026-04-01 00:00 |
00:44:33.85 |
+44:48:30.2 |
HIP 3604 |
17.48 |
| 2026-04-01 12:00 |
00:44:43.69 |
+44:48:47.6 |
HIP 3604 |
15.71 |
| 2026-04-02 00:00 |
00:44:53.52 |
+44:49:05.6 |
HIP 3604 |
13.94 |
| 2026-04-02 12:00 |
00:45:03.35 |
+44:49:24.2 |
HIP 3604 |
12.17 |
| 2026-04-03 00:00 |
00:45:13.18 |
+44:49:43.4 |
HIP 3604 |
10.40 |
| 2026-04-03 12:00 |
00:45:23.00 |
+44:50:03.2 |
HIP 3604 |
8.63 |
| 2026-04-04 00:00 |
00:45:32.81 |
+44:50:23.5 |
HIP 3604 |
6.86 |
| 2026-04-04 12:00 |
00:45:42.62 |
+44:50:44.4 |
HIP 3604 |
5.08 |
| 2026-04-05 00:00 |
00:45:52.42 |
+44:51:05.9 |
HIP 3604 |
3.31 |
| 2026-04-05 12:00 |
00:46:02.22 |
+44:51:27.9 |
HIP 3604 |
1.54 |
| 2026-04-06 00:00 |
00:46:12.00 |
+44:51:50.5 |
HIP 3604 |
0.26 |
| 2026-04-06 12:00 |
00:46:21.78 |
+44:52:13.7 |
HIP 3604 |
2.02 |
| 2026-04-07 00:00 |
00:46:31.54 |
+44:52:37.4 |
HIP 3604 |
3.79 |
| 2026-04-07 12:00 |
00:46:41.30 |
+44:53:01.7 |
HIP 3604 |
5.57 |
| 2026-04-08 00:00 |
00:46:51.05 |
+44:53:26.6 |
HIP 3604 |
7.34 |
| 2026-04-08 12:00 |
00:47:00.79 |
+44:53:52.0 |
HIP 3604 |
9.12 |
| 2026-04-09 00:00 |
00:47:10.51 |
+44:54:17.9 |
HIP 3604 |
10.89 |
| 2026-04-09 12:00 |
00:47:20.23 |
+44:54:44.4 |
HIP 3604 |
12.67 |
| 2026-04-10 00:00 |
00:47:29.93 |
+44:55:11.4 |
HIP 3779 |
11.71 |
| 2026-04-10 12:00 |
00:47:39.62 |
+44:55:39.0 |
HIP 3779 |
9.94 |
| 2026-04-11 00:00 |
00:47:49.29 |
+44:56:07.1 |
HIP 3779 |
8.16 |
| 2026-04-11 12:00 |
00:47:58.95 |
+44:56:35.7 |
HIP 3779 |
6.39 |
| 2026-04-12 00:00 |
00:48:08.60 |
+44:57:04.9 |
HIP 3779 |
4.61 |
| 2026-04-12 12:00 |
00:48:18.23 |
+44:57:34.6 |
HIP 3779 |
2.84 |
| 2026-04-13 00:00 |
00:48:27.85 |
+44:58:04.8 |
HIP 3779 |
1.06 |
| 2026-04-13 12:00 |
00:48:37.45 |
+44:58:35.5 |
HIP 3779 |
0.71 |
| 2026-04-14 00:00 |
00:48:47.03 |
+44:59:06.8 |
HIP 3779 |
2.48 |
| 2026-04-14 12:00 |
00:48:56.60 |
+44:59:38.5 |
HIP 3779 |
4.26 |
| 2026-04-15 00:00 |
00:49:06.14 |
+45:00:10.8 |
HIP 3779 |
6.03 |
| 2026-04-15 12:00 |
00:49:15.67 |
+45:00:43.6 |
HIP 3779 |
7.80 |
| 2026-04-16 00:00 |
00:49:25.18 |
+45:01:16.9 |
HIP 3919 |
9.44 |