| Parameter |
Value |
| Designation |
C/2021 A10 (NEOWISE) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-03-15T06:26:00.660480Z |
| Orbit solution date (soln_date, UTC) |
2021-07-01T22:12:55Z |
| Obs used |
116 |
| NEO |
- |
| M1 |
19.600 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-01-12T03:54:10.368000Z |
| Discovery magnitude (MPC) |
19.00 R |
| Discovery observatory (MPC) |
C51 · WISE |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-01-29.0000000 |
| e |
0.98633128 |
| q (au) |
1.268515 |
| a (au) |
92.804201 |
| i (deg) |
151.524714 |
| Ω (om, deg) |
188.347864 |
| ω (w, deg) |
82.268366 |
| M (ma, deg) |
359.950095 |
Magnitude
Scatter + Global Linear
$$
M_a = (19.470 + 2.456\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
19.470 |
| n |
2.456 |
| gf |
0.926 |
| gb |
-0.500 |
| k |
0.800 |
| δ90 |
1.147 |
| 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) |
| 2026-05-12 00:00 |
22:25:50.58 |
-32:39:06.5 |
HIP 110818 |
16.89 |
| 2026-05-12 12:00 |
22:25:51.78 |
-32:39:49.4 |
HIP 110818 |
16.92 |
| 2026-05-13 00:00 |
22:25:52.91 |
-32:40:32.8 |
HIP 110818 |
17.00 |
| 2026-05-13 12:00 |
22:25:53.97 |
-32:41:16.5 |
HIP 110818 |
17.13 |
| 2026-05-14 00:00 |
22:25:54.96 |
-32:42:00.8 |
HIP 110818 |
17.31 |
| 2026-05-14 12:00 |
22:25:55.88 |
-32:42:45.4 |
HIP 110818 |
17.53 |
| 2026-05-15 00:00 |
22:25:56.74 |
-32:43:30.5 |
HIP 110818 |
17.81 |
| 2026-05-15 12:00 |
22:25:57.52 |
-32:44:16.0 |
HIP 110818 |
18.13 |
| 2026-05-16 00:00 |
22:25:58.23 |
-32:45:01.9 |
HIP 110818 |
18.49 |
| 2026-05-16 12:00 |
22:25:58.87 |
-32:45:48.2 |
HIP 110818 |
18.89 |
| 2026-05-17 00:00 |
22:25:59.44 |
-32:46:35.0 |
HIP 110818 |
19.33 |
| 2026-05-17 12:00 |
22:25:59.94 |
-32:47:22.2 |
HIP 110818 |
19.81 |
| 2026-05-18 00:00 |
22:26:00.36 |
-32:48:09.8 |
HIP 110818 |
20.32 |
| 2026-05-18 12:00 |
22:26:00.72 |
-32:48:57.8 |
HIP 110818 |
20.87 |
| 2026-05-19 00:00 |
22:26:01.00 |
-32:49:46.2 |
HIP 110818 |
21.45 |
| 2026-05-19 12:00 |
22:26:01.21 |
-32:50:35.1 |
HIP 110818 |
22.05 |
| 2026-05-20 00:00 |
22:26:01.35 |
-32:51:24.3 |
HIP 110818 |
22.69 |
| 2026-05-20 12:00 |
22:26:01.42 |
-32:52:13.9 |
HIP 110818 |
23.35 |
| 2026-05-21 00:00 |
22:26:01.42 |
-32:53:03.9 |
HIP 110655 |
22.82 |
| 2026-05-21 12:00 |
22:26:01.34 |
-32:53:54.4 |
HIP 110655 |
22.11 |
| 2026-05-22 00:00 |
22:26:01.19 |
-32:54:45.2 |
HIP 110655 |
21.39 |
| 2026-05-22 12:00 |
22:26:00.97 |
-32:55:36.4 |
HIP 110655 |
20.67 |
| 2026-05-23 00:00 |
22:26:00.68 |
-32:56:27.9 |
HIP 110655 |
19.94 |
| 2026-05-23 12:00 |
22:26:00.31 |
-32:57:19.9 |
HIP 110655 |
19.21 |
| 2026-05-24 00:00 |
22:25:59.87 |
-32:58:12.2 |
HIP 110655 |
18.48 |
| 2026-05-24 12:00 |
22:25:59.36 |
-32:59:05.0 |
HIP 110655 |
17.75 |
| 2026-05-25 00:00 |
22:25:58.78 |
-32:59:58.1 |
HIP 110655 |
17.01 |
| 2026-05-25 12:00 |
22:25:58.12 |
-33:00:51.5 |
HIP 110655 |
16.28 |
| 2026-05-26 00:00 |
22:25:57.39 |
-33:01:45.3 |
HIP 110655 |
15.55 |
| 2026-05-26 12:00 |
22:25:56.58 |
-33:02:39.5 |
HIP 110655 |
14.82 |
| 2026-05-27 00:00 |
22:25:55.71 |
-33:03:34.1 |
HIP 110655 |
14.11 |
| 2026-05-27 12:00 |
22:25:54.76 |
-33:04:29.0 |
HIP 110655 |
13.40 |
| 2026-05-28 00:00 |
22:25:53.73 |
-33:05:24.2 |
HIP 110655 |
12.70 |
| 2026-05-28 12:00 |
22:25:52.64 |
-33:06:19.8 |
HIP 110655 |
12.02 |
| 2026-05-29 00:00 |
22:25:51.47 |
-33:07:15.8 |
HIP 110655 |
11.37 |
| 2026-05-29 12:00 |
22:25:50.22 |
-33:08:12.0 |
HIP 110655 |
10.74 |
| 2026-05-30 00:00 |
22:25:48.91 |
-33:09:08.7 |
HIP 110655 |
10.16 |
| 2026-05-30 12:00 |
22:25:47.51 |
-33:10:05.6 |
HIP 110655 |
9.62 |
| 2026-05-31 00:00 |
22:25:46.05 |
-33:11:02.9 |
HIP 110655 |
9.14 |
| 2026-05-31 12:00 |
22:25:44.51 |
-33:12:00.6 |
HIP 110655 |
8.74 |
| 2026-06-01 00:00 |
22:25:42.90 |
-33:12:58.5 |
HIP 110655 |
8.42 |
| 2026-06-01 12:00 |
22:25:41.22 |
-33:13:56.8 |
HIP 110655 |
8.21 |
| 2026-06-02 00:00 |
22:25:39.46 |
-33:14:55.4 |
HIP 110708 |
7.63 |