| 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) |
| 2026-07-29 00:00 |
07:03:25.24 |
+27:12:51.2 |
HIP 34030 |
12.79 |
| 2026-07-29 12:00 |
07:03:33.48 |
+27:13:00.5 |
HIP 34030 |
12.70 |
| 2026-07-30 00:00 |
07:03:41.70 |
+27:13:10.0 |
HIP 34030 |
12.88 |
| 2026-07-30 12:00 |
07:03:49.88 |
+27:13:19.5 |
HIP 34030 |
13.32 |
| 2026-07-31 00:00 |
07:03:58.04 |
+27:13:29.1 |
HIP 34030 |
13.98 |
| 2026-07-31 12:00 |
07:04:06.16 |
+27:13:38.8 |
HIP 34030 |
14.83 |
| 2026-08-01 00:00 |
07:04:14.26 |
+27:13:48.6 |
HIP 34030 |
15.85 |
| 2026-08-01 12:00 |
07:04:22.33 |
+27:13:58.5 |
HIP 34030 |
16.99 |
| 2026-08-02 00:00 |
07:04:30.36 |
+27:14:08.5 |
HIP 34030 |
18.24 |
| 2026-08-02 12:00 |
07:04:38.36 |
+27:14:18.6 |
HIP 34030 |
19.57 |
| 2026-08-03 00:00 |
07:04:46.33 |
+27:14:28.7 |
HIP 34222 |
18.56 |
| 2026-08-03 12:00 |
07:04:54.27 |
+27:14:39.0 |
HIP 34222 |
17.29 |
| 2026-08-04 00:00 |
07:05:02.17 |
+27:14:49.4 |
HIP 34222 |
16.12 |
| 2026-08-04 12:00 |
07:05:10.05 |
+27:15:00.0 |
HIP 34222 |
15.07 |
| 2026-08-05 00:00 |
07:05:17.88 |
+27:15:10.5 |
HIP 34222 |
14.16 |
| 2026-08-05 12:00 |
07:05:25.68 |
+27:15:21.2 |
HIP 34222 |
13.43 |
| 2026-08-06 00:00 |
07:05:33.45 |
+27:15:32.0 |
HIP 34222 |
12.88 |
| 2026-08-06 12:00 |
07:05:41.18 |
+27:15:42.9 |
HIP 34222 |
12.55 |
| 2026-08-07 00:00 |
07:05:48.88 |
+27:15:54.0 |
HIP 34222 |
12.45 |
| 2026-08-07 12:00 |
07:05:56.54 |
+27:16:05.1 |
HIP 34222 |
12.58 |
| 2026-08-08 00:00 |
07:06:04.16 |
+27:16:16.3 |
HIP 34222 |
12.94 |
| 2026-08-08 12:00 |
07:06:11.74 |
+27:16:27.7 |
HIP 34222 |
13.49 |
| 2026-08-09 00:00 |
07:06:19.29 |
+27:16:39.2 |
HIP 34222 |
14.22 |
| 2026-08-09 12:00 |
07:06:26.80 |
+27:16:50.8 |
HIP 34222 |
15.10 |
| 2026-08-10 00:00 |
07:06:34.26 |
+27:17:02.5 |
HIP 34222 |
16.10 |
| 2026-08-10 12:00 |
07:06:41.69 |
+27:17:14.3 |
HIP 34222 |
17.19 |
| 2026-08-11 00:00 |
07:06:49.08 |
+27:17:26.2 |
HIP 34222 |
18.36 |
| 2026-08-11 12:00 |
07:06:56.43 |
+27:17:38.3 |
HIP 34222 |
19.59 |
| 2026-08-12 00:00 |
07:07:03.73 |
+27:17:50.4 |
HIP 34222 |
20.87 |
| 2026-08-12 12:00 |
07:07:10.99 |
+27:18:02.7 |
HIP 34222 |
22.19 |
| 2026-08-13 00:00 |
07:07:18.21 |
+27:18:15.2 |
HIP 34222 |
23.53 |
| 2026-08-13 12:00 |
07:07:25.39 |
+27:18:27.7 |
HIP 34222 |
24.90 |
| 2026-08-14 00:00 |
07:07:32.52 |
+27:18:40.4 |
HIP 34222 |
26.28 |
| 2026-08-14 12:00 |
07:07:39.61 |
+27:18:53.2 |
HIP 34522 |
27.26 |
| 2026-08-15 00:00 |
07:07:46.66 |
+27:19:06.1 |
HIP 34522 |
25.95 |
| 2026-08-15 12:00 |
07:07:53.65 |
+27:19:19.2 |
HIP 34522 |
24.69 |
| 2026-08-16 00:00 |
07:08:00.61 |
+27:19:32.3 |
HIP 34522 |
23.47 |
| 2026-08-16 12:00 |
07:08:07.51 |
+27:19:45.7 |
HIP 34522 |
22.29 |
| 2026-08-17 00:00 |
07:08:14.38 |
+27:19:59.1 |
HIP 34522 |
21.17 |
| 2026-08-17 12:00 |
07:08:21.19 |
+27:20:12.7 |
HIP 34522 |
20.10 |
| 2026-08-18 00:00 |
07:08:27.95 |
+27:20:26.4 |
HIP 34522 |
19.10 |
| 2026-08-18 12:00 |
07:08:34.67 |
+27:20:40.3 |
HIP 34522 |
18.18 |
| 2026-08-19 00:00 |
07:08:41.34 |
+27:20:54.2 |
HIP 34522 |
17.34 |