C/2021 E3 (ZTF)
| Parameter |
Value |
| Designation |
C/2021 E3 (ZTF) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-06-11T21:41:58.482240Z |
| Orbit solution date (soln_date, UTC) |
2024-04-13T16:42:29Z |
| Obs used |
1490 |
| NEO |
- |
| M1 |
11.100 |
| K1 |
5.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-03-09T12:41:11.904000Z |
| Discovery magnitude (MPC) |
19.60 r |
| Discovery observatory (MPC) |
I41 · Palomar Mountain–ZTF |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-02-28.0000000 |
| e |
1.00086348 |
| q (au) |
1.777410 |
| a (au) |
-2058.416001 |
| i (deg) |
112.555637 |
| Ω (om, deg) |
104.468418 |
| ω (w, deg) |
228.845737 |
| M (ma, deg) |
-0.001097 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.650 + 3.246\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.650 |
| n |
3.246 |
| gf |
1.000 |
| gb |
-0.558 |
| 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 |
| 2021-03-09 |
2022-06-10 |
+4.2489 |
-2.716 |
| 2022-06-16 |
2022-11-11 |
+10.7149 |
-4.279 |
| 2022-11-11 |
2024-01-13 |
-0.3955 |
+0.570 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
06:47:29.30 |
+26:07:24.0 |
HIP 32543 |
0.55 |
| 2026-02-03 12:00 |
06:47:18.70 |
+26:07:54.5 |
HIP 32543 |
1.97 |
| 2026-02-04 00:00 |
06:47:08.17 |
+26:08:24.7 |
HIP 32543 |
4.38 |
| 2026-02-04 12:00 |
06:46:57.71 |
+26:08:54.8 |
HIP 32543 |
6.78 |
| 2026-02-05 00:00 |
06:46:47.32 |
+26:09:24.7 |
HIP 32543 |
9.16 |
| 2026-02-05 12:00 |
06:46:37.01 |
+26:09:54.3 |
HIP 32543 |
11.52 |
| 2026-02-06 00:00 |
06:46:26.78 |
+26:10:23.7 |
HIP 32543 |
13.87 |
| 2026-02-06 12:00 |
06:46:16.62 |
+26:10:52.9 |
HIP 32543 |
16.20 |
| 2026-02-07 00:00 |
06:46:06.54 |
+26:11:21.8 |
HIP 32543 |
18.51 |
| 2026-02-07 12:00 |
06:45:56.53 |
+26:11:50.6 |
HIP 32306 |
17.00 |
| 2026-02-08 00:00 |
06:45:46.60 |
+26:12:19.1 |
HIP 32306 |
14.98 |
| 2026-02-08 12:00 |
06:45:36.75 |
+26:12:47.4 |
HIP 32306 |
13.06 |
| 2026-02-09 00:00 |
06:45:26.98 |
+26:13:15.5 |
HIP 32306 |
11.28 |
| 2026-02-09 12:00 |
06:45:17.29 |
+26:13:43.4 |
HIP 32306 |
9.71 |
| 2026-02-10 00:00 |
06:45:07.69 |
+26:14:11.1 |
HIP 32306 |
8.45 |
| 2026-02-10 12:00 |
06:44:58.16 |
+26:14:38.5 |
HIP 32306 |
7.64 |
| 2026-02-11 00:00 |
06:44:48.72 |
+26:15:05.7 |
HIP 32306 |
7.40 |
| 2026-02-11 12:00 |
06:44:39.36 |
+26:15:32.8 |
HIP 32306 |
7.78 |
| 2026-02-12 00:00 |
06:44:30.08 |
+26:15:59.6 |
HIP 32306 |
8.67 |
| 2026-02-12 12:00 |
06:44:20.89 |
+26:16:26.2 |
HIP 32232 |
8.96 |
| 2026-02-13 00:00 |
06:44:11.78 |
+26:16:52.6 |
HIP 32232 |
7.25 |
| 2026-02-13 12:00 |
06:44:02.76 |
+26:17:18.7 |
HIP 32232 |
5.80 |
| 2026-02-14 00:00 |
06:43:53.82 |
+26:17:44.7 |
HIP 32232 |
4.83 |
| 2026-02-14 12:00 |
06:43:44.98 |
+26:18:10.5 |
HIP 32232 |
4.64 |
| 2026-02-15 00:00 |
06:43:36.22 |
+26:18:36.0 |
HIP 32232 |
5.27 |
| 2026-02-15 12:00 |
06:43:27.54 |
+26:19:01.4 |
HIP 32232 |
6.48 |
| 2026-02-16 00:00 |
06:43:18.96 |
+26:19:26.5 |
HIP 32232 |
7.99 |
| 2026-02-16 12:00 |
06:43:10.47 |
+26:19:51.4 |
HIP 32232 |
9.64 |
| 2026-02-17 00:00 |
06:43:02.07 |
+26:20:16.2 |
HIP 32232 |
11.38 |
| 2026-02-17 12:00 |
06:42:53.76 |
+26:20:40.7 |
HIP 32232 |
13.14 |
| 2026-02-18 00:00 |
06:42:45.53 |
+26:21:05.0 |
HIP 32057 |
12.03 |
| 2026-02-18 12:00 |
06:42:37.41 |
+26:21:29.2 |
HIP 32057 |
10.37 |
| 2026-02-19 00:00 |
06:42:29.37 |
+26:21:53.1 |
HIP 32057 |
8.81 |
| 2026-02-19 12:00 |
06:42:21.43 |
+26:22:16.8 |
HIP 32057 |
7.40 |
| 2026-02-20 00:00 |
06:42:13.58 |
+26:22:40.3 |
HIP 32057 |
6.21 |
| 2026-02-20 12:00 |
06:42:05.82 |
+26:23:03.7 |
HIP 32057 |
5.40 |
| 2026-02-21 00:00 |
06:41:58.16 |
+26:23:26.8 |
HIP 32057 |
5.09 |
| 2026-02-21 12:00 |
06:41:50.59 |
+26:23:49.7 |
HIP 32057 |
5.38 |
| 2026-02-22 00:00 |
06:41:43.11 |
+26:24:12.5 |
HIP 32057 |
6.15 |
| 2026-02-22 12:00 |
06:41:35.74 |
+26:24:35.0 |
HIP 32057 |
7.24 |
| 2026-02-23 00:00 |
06:41:28.45 |
+26:24:57.4 |
HIP 32057 |
8.51 |
| 2026-02-23 12:00 |
06:41:21.27 |
+26:25:19.5 |
HIP 32057 |
9.88 |
| 2026-02-24 00:00 |
06:41:14.18 |
+26:25:41.5 |
HIP 32057 |
11.31 |