C/2021 A10 (NEOWISE)
| 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) |
| 2026-02-03 00:00 |
22:07:01.41 |
-32:44:20.3 |
HIP 109285 |
22.74 |
| 2026-02-03 12:00 |
22:07:08.92 |
-32:43:41.2 |
HIP 109285 |
22.04 |
| 2026-02-04 00:00 |
22:07:16.46 |
-32:43:02.5 |
HIP 109285 |
21.44 |
| 2026-02-04 12:00 |
22:07:24.00 |
-32:42:24.0 |
HIP 109326 |
20.32 |
| 2026-02-05 00:00 |
22:07:31.56 |
-32:41:45.7 |
HIP 109326 |
18.61 |
| 2026-02-05 12:00 |
22:07:39.13 |
-32:41:07.7 |
HIP 109326 |
16.90 |
| 2026-02-06 00:00 |
22:07:46.71 |
-32:40:29.9 |
HIP 109326 |
15.19 |
| 2026-02-06 12:00 |
22:07:54.31 |
-32:39:52.5 |
HIP 109326 |
13.48 |
| 2026-02-07 00:00 |
22:08:01.91 |
-32:39:15.3 |
HIP 109326 |
11.77 |
| 2026-02-07 12:00 |
22:08:09.53 |
-32:38:38.3 |
HIP 109326 |
10.06 |
| 2026-02-08 00:00 |
22:08:17.16 |
-32:38:01.7 |
HIP 109326 |
8.36 |
| 2026-02-08 12:00 |
22:08:24.79 |
-32:37:25.3 |
HIP 109326 |
6.65 |
| 2026-02-09 00:00 |
22:08:32.44 |
-32:36:49.2 |
HIP 109326 |
4.96 |
| 2026-02-09 12:00 |
22:08:40.09 |
-32:36:13.3 |
HIP 109326 |
3.29 |
| 2026-02-10 00:00 |
22:08:47.75 |
-32:35:37.8 |
HIP 109326 |
1.72 |
| 2026-02-10 12:00 |
22:08:55.42 |
-32:35:02.5 |
HIP 109326 |
1.00 |
| 2026-02-11 00:00 |
22:09:03.10 |
-32:34:27.6 |
HIP 109326 |
2.22 |
| 2026-02-11 12:00 |
22:09:10.78 |
-32:33:52.9 |
HIP 109326 |
3.84 |
| 2026-02-12 00:00 |
22:09:18.47 |
-32:33:18.5 |
HIP 109326 |
5.52 |
| 2026-02-12 12:00 |
22:09:26.16 |
-32:32:44.4 |
HIP 109407 |
7.21 |
| 2026-02-13 00:00 |
22:09:33.86 |
-32:32:10.6 |
HIP 109407 |
6.04 |
| 2026-02-13 12:00 |
22:09:41.56 |
-32:31:37.1 |
HIP 109407 |
5.19 |
| 2026-02-14 00:00 |
22:09:49.27 |
-32:31:04.0 |
HIP 109422 |
4.45 |
| 2026-02-14 12:00 |
22:09:56.98 |
-32:30:31.1 |
HIP 109422 |
3.40 |
| 2026-02-15 00:00 |
22:10:04.69 |
-32:29:58.5 |
HIP 109422 |
3.04 |
| 2026-02-15 12:00 |
22:10:12.40 |
-32:29:26.3 |
HIP 109422 |
3.57 |
| 2026-02-16 00:00 |
22:10:20.12 |
-32:28:54.4 |
HIP 109422 |
4.69 |
| 2026-02-16 12:00 |
22:10:27.83 |
-32:28:22.8 |
HIP 109422 |
6.09 |
| 2026-02-17 00:00 |
22:10:35.55 |
-32:27:51.5 |
HIP 109422 |
7.62 |
| 2026-02-17 12:00 |
22:10:43.27 |
-32:27:20.5 |
HIP 109422 |
9.21 |
| 2026-02-18 00:00 |
22:10:50.98 |
-32:26:49.9 |
HIP 109422 |
10.83 |
| 2026-02-18 12:00 |
22:10:58.69 |
-32:26:19.6 |
HIP 109422 |
12.47 |
| 2026-02-19 00:00 |
22:11:06.41 |
-32:25:49.6 |
HIP 109422 |
14.12 |
| 2026-02-19 12:00 |
22:11:14.12 |
-32:25:20.0 |
HIP 109605 |
13.59 |
| 2026-02-20 00:00 |
22:11:21.82 |
-32:24:50.7 |
HIP 109605 |
12.49 |
| 2026-02-20 12:00 |
22:11:29.52 |
-32:24:21.7 |
HIP 109605 |
11.54 |
| 2026-02-21 00:00 |
22:11:37.22 |
-32:23:53.1 |
HIP 109605 |
10.76 |
| 2026-02-21 12:00 |
22:11:44.92 |
-32:23:24.8 |
HIP 109605 |
10.21 |
| 2026-02-22 00:00 |
22:11:52.60 |
-32:22:56.9 |
HIP 109605 |
9.91 |
| 2026-02-22 12:00 |
22:12:00.29 |
-32:22:29.3 |
HIP 109605 |
9.88 |
| 2026-02-23 00:00 |
22:12:07.96 |
-32:22:02.1 |
HIP 109605 |
10.14 |
| 2026-02-23 12:00 |
22:12:15.63 |
-32:21:35.3 |
HIP 109605 |
10.65 |
| 2026-02-24 00:00 |
22:12:23.29 |
-32:21:08.7 |
HIP 109605 |
11.38 |