| 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 |
0.896 |
| gb |
-0.500 |
| k |
0.800 |
| δ90 |
1.149 |
| 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) |
| 2026-06-01 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 |
| 2026-06-02 12:00 |
22:25:37.62 |
-33:15:54.3 |
HIP 110708 |
6.81 |
| 2026-06-03 00:00 |
22:25:35.72 |
-33:16:53.5 |
HIP 110708 |
6.05 |
| 2026-06-03 12:00 |
22:25:33.74 |
-33:17:53.1 |
HIP 110708 |
5.41 |
| 2026-06-04 00:00 |
22:25:31.68 |
-33:18:52.9 |
HIP 110708 |
4.92 |
| 2026-06-04 12:00 |
22:25:29.55 |
-33:19:53.1 |
HIP 110708 |
4.65 |
| 2026-06-05 00:00 |
22:25:27.35 |
-33:20:53.5 |
HIP 110708 |
4.65 |
| 2026-06-05 12:00 |
22:25:25.07 |
-33:21:54.3 |
HIP 110708 |
4.92 |
| 2026-06-06 00:00 |
22:25:22.72 |
-33:22:55.3 |
HIP 110708 |
5.43 |
| 2026-06-06 12:00 |
22:25:20.30 |
-33:23:56.6 |
HIP 110708 |
6.12 |
| 2026-06-07 00:00 |
22:25:17.80 |
-33:24:58.2 |
HIP 110708 |
6.95 |
| 2026-06-07 12:00 |
22:25:15.22 |
-33:26:00.1 |
HIP 110708 |
7.87 |
| 2026-06-08 00:00 |
22:25:12.58 |
-33:27:02.2 |
HIP 110708 |
8.87 |
| 2026-06-08 12:00 |
22:25:09.85 |
-33:28:04.7 |
HIP 110708 |
9.92 |
| 2026-06-09 00:00 |
22:25:07.06 |
-33:29:07.4 |
HIP 110708 |
11.01 |
| 2026-06-09 12:00 |
22:25:04.19 |
-33:30:10.3 |
HIP 110708 |
12.14 |
| 2026-06-10 00:00 |
22:25:01.24 |
-33:31:13.6 |
HIP 110708 |
13.30 |
| 2026-06-10 12:00 |
22:24:58.22 |
-33:32:17.1 |
HIP 110708 |
14.48 |
| 2026-06-11 00:00 |
22:24:55.13 |
-33:33:20.8 |
HIP 110579 |
14.14 |
| 2026-06-11 12:00 |
22:24:51.96 |
-33:34:24.8 |
HIP 110579 |
12.92 |
| 2026-06-12 00:00 |
22:24:48.72 |
-33:35:29.0 |
HIP 110579 |
11.70 |
| 2026-06-12 12:00 |
22:24:45.41 |
-33:36:33.5 |
HIP 110579 |
10.47 |
| 2026-06-13 00:00 |
22:24:42.02 |
-33:37:38.2 |
HIP 110579 |
9.24 |
| 2026-06-13 12:00 |
22:24:38.56 |
-33:38:43.1 |
HIP 110579 |
8.01 |
| 2026-06-14 00:00 |
22:24:35.02 |
-33:39:48.2 |
HIP 110579 |
6.79 |
| 2026-06-14 12:00 |
22:24:31.41 |
-33:40:53.6 |
HIP 110579 |
5.60 |
| 2026-06-15 00:00 |
22:24:27.72 |
-33:41:59.2 |
HIP 110579 |
4.47 |
| 2026-06-15 12:00 |
22:24:23.96 |
-33:43:05.0 |
HIP 110579 |
3.48 |
| 2026-06-16 00:00 |
22:24:20.13 |
-33:44:11.0 |
HIP 110579 |
2.78 |
| 2026-06-16 12:00 |
22:24:16.23 |
-33:45:17.2 |
HIP 110579 |
2.65 |
| 2026-06-17 00:00 |
22:24:12.25 |
-33:46:23.6 |
HIP 110579 |
3.17 |
| 2026-06-17 12:00 |
22:24:08.20 |
-33:47:30.2 |
HIP 110579 |
4.11 |
| 2026-06-18 00:00 |
22:24:04.08 |
-33:48:36.9 |
HIP 110579 |
5.27 |
| 2026-06-18 12:00 |
22:23:59.88 |
-33:49:43.9 |
HIP 110579 |
6.52 |
| 2026-06-19 00:00 |
22:23:55.61 |
-33:50:51.0 |
HIP 110579 |
7.84 |
| 2026-06-19 12:00 |
22:23:51.27 |
-33:51:58.3 |
HIP 110579 |
9.20 |
| 2026-06-20 00:00 |
22:23:46.86 |
-33:53:05.7 |
HIP 110579 |
10.59 |
| 2026-06-20 12:00 |
22:23:42.38 |
-33:54:13.3 |
HIP 110579 |
12.00 |
| 2026-06-21 00:00 |
22:23:37.82 |
-33:55:21.0 |
HIP 110579 |
13.44 |
| 2026-06-21 12:00 |
22:23:33.20 |
-33:56:28.9 |
HIP 110579 |
14.88 |
| 2026-06-22 00:00 |
22:23:28.50 |
-33:57:37.0 |
HIP 110579 |
16.35 |