| Parameter |
Value |
| Designation |
C/2021 E3 (ZTF) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-06-11T21:41:58.525440Z |
| Orbit solution date (soln_date, UTC) |
2026-03-11T21:13:02Z |
| Obs used |
1491 |
| 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) |
-2058.429778 |
| 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) |
| 2026-09-20 00:00 |
07:13:47.17 |
+27:41:12.0 |
HIP 34885 |
10.66 |
| 2026-09-20 12:00 |
07:13:49.74 |
+27:41:36.6 |
HIP 34885 |
10.94 |
| 2026-09-21 00:00 |
07:13:52.25 |
+27:42:01.4 |
HIP 34885 |
11.24 |
| 2026-09-21 12:00 |
07:13:54.67 |
+27:42:26.4 |
HIP 34885 |
11.55 |
| 2026-09-22 00:00 |
07:13:57.02 |
+27:42:51.5 |
HIP 34885 |
11.88 |
| 2026-09-22 12:00 |
07:13:59.29 |
+27:43:16.8 |
HIP 34885 |
12.22 |
| 2026-09-23 00:00 |
07:14:01.49 |
+27:43:42.4 |
HIP 34885 |
12.57 |
| 2026-09-23 12:00 |
07:14:03.61 |
+27:44:08.1 |
HIP 34885 |
12.92 |
| 2026-09-24 00:00 |
07:14:05.65 |
+27:44:33.9 |
HIP 34885 |
13.28 |
| 2026-09-24 12:00 |
07:14:07.61 |
+27:45:00.0 |
HIP 34885 |
13.64 |
| 2026-09-25 00:00 |
07:14:09.49 |
+27:45:26.2 |
HIP 34885 |
13.99 |
| 2026-09-25 12:00 |
07:14:11.29 |
+27:45:52.7 |
HIP 34885 |
14.35 |
| 2026-09-26 00:00 |
07:14:13.02 |
+27:46:19.3 |
HIP 34885 |
14.70 |
| 2026-09-26 12:00 |
07:14:14.66 |
+27:46:46.1 |
HIP 34885 |
15.05 |
| 2026-09-27 00:00 |
07:14:16.23 |
+27:47:13.0 |
HIP 34885 |
15.40 |
| 2026-09-27 12:00 |
07:14:17.72 |
+27:47:40.2 |
HIP 34885 |
15.74 |
| 2026-09-28 00:00 |
07:14:19.12 |
+27:48:07.5 |
HIP 34885 |
16.08 |
| 2026-09-28 12:00 |
07:14:20.45 |
+27:48:35.1 |
HIP 34885 |
16.41 |
| 2026-09-29 00:00 |
07:14:21.69 |
+27:49:02.8 |
HIP 34885 |
16.74 |
| 2026-09-29 12:00 |
07:14:22.86 |
+27:49:30.6 |
HIP 34885 |
17.05 |
| 2026-09-30 00:00 |
07:14:23.94 |
+27:49:58.7 |
HIP 34885 |
17.37 |
| 2026-09-30 12:00 |
07:14:24.94 |
+27:50:26.9 |
HIP 34885 |
17.67 |
| 2026-10-01 00:00 |
07:14:25.86 |
+27:50:55.4 |
HIP 34885 |
17.97 |
| 2026-10-01 12:00 |
07:14:26.69 |
+27:51:24.0 |
HIP 34885 |
18.26 |
| 2026-10-02 00:00 |
07:14:27.45 |
+27:51:52.8 |
HIP 34885 |
18.54 |
| 2026-10-02 12:00 |
07:14:28.12 |
+27:52:21.7 |
HIP 34885 |
18.82 |
| 2026-10-03 00:00 |
07:14:28.71 |
+27:52:50.9 |
HIP 34885 |
19.08 |
| 2026-10-03 12:00 |
07:14:29.21 |
+27:53:20.2 |
HIP 34885 |
19.35 |
| 2026-10-04 00:00 |
07:14:29.63 |
+27:53:49.7 |
HIP 35152 |
19.34 |
| 2026-10-04 12:00 |
07:14:29.97 |
+27:54:19.4 |
HIP 35152 |
19.27 |
| 2026-10-05 00:00 |
07:14:30.22 |
+27:54:49.3 |
HIP 35152 |
19.24 |
| 2026-10-05 12:00 |
07:14:30.39 |
+27:55:19.3 |
HIP 35152 |
19.23 |
| 2026-10-06 00:00 |
07:14:30.47 |
+27:55:49.5 |
HIP 35152 |
19.26 |
| 2026-10-06 12:00 |
07:14:30.47 |
+27:56:20.0 |
HIP 35152 |
19.31 |
| 2026-10-07 00:00 |
07:14:30.38 |
+27:56:50.5 |
HIP 35152 |
19.40 |
| 2026-10-07 12:00 |
07:14:30.21 |
+27:57:21.3 |
HIP 35152 |
19.53 |
| 2026-10-08 00:00 |
07:14:29.95 |
+27:57:52.2 |
HIP 35152 |
19.68 |
| 2026-10-08 12:00 |
07:14:29.61 |
+27:58:23.4 |
HIP 35152 |
19.87 |
| 2026-10-09 00:00 |
07:14:29.18 |
+27:58:54.6 |
HIP 35152 |
20.08 |
| 2026-10-09 12:00 |
07:14:28.66 |
+27:59:26.1 |
HIP 35152 |
20.33 |
| 2026-10-10 00:00 |
07:14:28.05 |
+27:59:57.7 |
HIP 35152 |
20.61 |
| 2026-10-10 12:00 |
07:14:27.36 |
+28:00:29.6 |
HIP 35152 |
20.92 |
| 2026-10-11 00:00 |
07:14:26.58 |
+28:01:01.5 |
HIP 35152 |
21.25 |