| 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) |
| 2026-03-26 00:00 |
22:19:31.36 |
-32:06:39.6 |
HIP 110272 |
13.93 |
| 2026-03-26 12:00 |
22:19:37.66 |
-32:06:38.2 |
HIP 110272 |
13.13 |
| 2026-03-27 00:00 |
22:19:43.93 |
-32:06:37.4 |
HIP 110272 |
12.44 |
| 2026-03-27 12:00 |
22:19:50.16 |
-32:06:37.0 |
HIP 110272 |
11.87 |
| 2026-03-28 00:00 |
22:19:56.35 |
-32:06:37.0 |
HIP 110272 |
11.44 |
| 2026-03-28 12:00 |
22:20:02.50 |
-32:06:37.5 |
HIP 110272 |
11.15 |
| 2026-03-29 00:00 |
22:20:08.62 |
-32:06:38.5 |
HIP 110272 |
11.01 |
| 2026-03-29 12:00 |
22:20:14.69 |
-32:06:39.9 |
HIP 110272 |
11.04 |
| 2026-03-30 00:00 |
22:20:20.73 |
-32:06:41.8 |
HIP 110272 |
11.22 |
| 2026-03-30 12:00 |
22:20:26.73 |
-32:06:44.2 |
HIP 110272 |
11.54 |
| 2026-03-31 00:00 |
22:20:32.68 |
-32:06:47.0 |
HIP 110272 |
12.00 |
| 2026-03-31 12:00 |
22:20:38.60 |
-32:06:50.3 |
HIP 110272 |
12.57 |
| 2026-04-01 00:00 |
22:20:44.48 |
-32:06:54.1 |
HIP 110272 |
13.24 |
| 2026-04-01 12:00 |
22:20:50.31 |
-32:06:58.3 |
HIP 110272 |
13.99 |
| 2026-04-02 00:00 |
22:20:56.10 |
-32:07:03.0 |
HIP 110272 |
14.80 |
| 2026-04-02 12:00 |
22:21:01.85 |
-32:07:08.2 |
HIP 110272 |
15.67 |
| 2026-04-03 00:00 |
22:21:07.56 |
-32:07:13.8 |
HIP 110272 |
16.58 |
| 2026-04-03 12:00 |
22:21:13.23 |
-32:07:19.9 |
HIP 110272 |
17.53 |
| 2026-04-04 00:00 |
22:21:18.85 |
-32:07:26.5 |
HIP 110272 |
18.50 |
| 2026-04-04 12:00 |
22:21:24.43 |
-32:07:33.6 |
HIP 110480 |
19.28 |
| 2026-04-05 00:00 |
22:21:29.96 |
-32:07:41.1 |
HIP 110480 |
18.30 |
| 2026-04-05 12:00 |
22:21:35.45 |
-32:07:49.1 |
HIP 110480 |
17.36 |
| 2026-04-06 00:00 |
22:21:40.90 |
-32:07:57.6 |
HIP 110480 |
16.45 |
| 2026-04-06 12:00 |
22:21:46.30 |
-32:08:06.5 |
HIP 110480 |
15.60 |
| 2026-04-07 00:00 |
22:21:51.65 |
-32:08:15.9 |
HIP 110480 |
14.80 |
| 2026-04-07 12:00 |
22:21:56.96 |
-32:08:25.9 |
HIP 110480 |
14.06 |
| 2026-04-08 00:00 |
22:22:02.23 |
-32:08:36.2 |
HIP 110480 |
13.38 |
| 2026-04-08 12:00 |
22:22:07.44 |
-32:08:47.1 |
HIP 110480 |
12.79 |
| 2026-04-09 00:00 |
22:22:12.61 |
-32:08:58.4 |
HIP 110480 |
12.28 |
| 2026-04-09 12:00 |
22:22:17.73 |
-32:09:10.3 |
HIP 110480 |
11.86 |
| 2026-04-10 00:00 |
22:22:22.80 |
-32:09:22.6 |
HIP 110480 |
11.55 |
| 2026-04-10 12:00 |
22:22:27.83 |
-32:09:35.4 |
HIP 110480 |
11.34 |
| 2026-04-11 00:00 |
22:22:32.80 |
-32:09:48.6 |
HIP 110480 |
11.25 |
| 2026-04-11 12:00 |
22:22:37.73 |
-32:10:02.4 |
HIP 110480 |
11.27 |
| 2026-04-12 00:00 |
22:22:42.61 |
-32:10:16.6 |
HIP 110480 |
11.40 |
| 2026-04-12 12:00 |
22:22:47.43 |
-32:10:31.3 |
HIP 110480 |
11.63 |
| 2026-04-13 00:00 |
22:22:52.21 |
-32:10:46.5 |
HIP 110480 |
11.95 |
| 2026-04-13 12:00 |
22:22:56.93 |
-32:11:02.2 |
HIP 110480 |
12.37 |
| 2026-04-14 00:00 |
22:23:01.61 |
-32:11:18.4 |
HIP 110480 |
12.85 |
| 2026-04-14 12:00 |
22:23:06.23 |
-32:11:35.0 |
HIP 110480 |
13.41 |
| 2026-04-15 00:00 |
22:23:10.80 |
-32:11:52.2 |
HIP 110480 |
14.02 |
| 2026-04-15 12:00 |
22:23:15.32 |
-32:12:09.8 |
HIP 110480 |
14.67 |
| 2026-04-16 00:00 |
22:23:19.78 |
-32:12:27.9 |
HIP 110480 |
15.36 |