메타데이터
| 항목 |
값 |
| Designation |
C/2021 A4 (NEOWISE) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-03-20T00:53:23.712000Z |
| Orbit solution date (soln_date, UTC) |
2022-03-08T19:43:19Z |
| Obs used |
683 |
| NEO |
- |
| M1 |
13.600 |
| K1 |
28.500 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2021-01-03T22:02:49.632000Z |
| Discovery magnitude (MPC) |
20.00 R |
| Discovery observatory (MPC) |
C51 · WISE |
Osculating 궤도요소
| 항목 |
값 |
| Epoch (epoch_cal, TDB) |
2021-02-16.0000000 |
| e |
0.97324748 |
| q (au) |
1.145476 |
| a (au) |
42.817518 |
| i (deg) |
111.569834 |
| Ω (om, deg) |
307.084762 |
| ω (w, deg) |
204.665566 |
| M (ma, deg) |
359.887300 |
밝기
산란 + 전체 선형
$$
M_a = (14.236 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
모델 상수
| 항목 |
값 |
| H0 |
14.236 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| k |
1.000 |
| δ90 |
10.000 |
| 파라미터 |
기호 |
범위 |
설명 |
| 태양·지구거리 1 AU에서의 절대등급 |
H0 |
-5 to 20 |
혜성의 고유 밝기 |
| 광도 기울기 파라미터 |
n |
2 to 6 |
태양거리 변화에 따른 밝기 변화율 |
| 전방 산란 비대칭 계수 |
gf |
0.8 to 1 |
전방 산란의 강도 |
| 후방 산란 비대칭 계수 |
gb |
-1 to -0.5 |
후방 산란의 강도 |
| 분할 계수 |
k |
0.8 to 1 |
전·후방 산란 기여도 비율 |
| 먼지/가스 밝기 비 |
δ90 |
1 to 10 |
코마에서 먼지 산란 대비 가스 방출의 상대 기여 |
참고: EPSC-DPS2025-160
잔차 (구간 선형)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| 시작일 (UTC) |
끝 (UTC) |
a |
b |
| 2021-01-03 |
2021-03-19 |
+14.1648 |
-1.643 |
| 2021-03-21 |
2021-07-07 |
-3.2765 |
-1.725 |
log10 r = log10(태양거리/AU), Δ = 지구거리(AU)
천체력
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
21:02:55.12 |
-21:20:21.8 |
HIP 103808 |
11.04 |
| 2026-03-26 12:00 |
21:02:59.46 |
-21:19:59.6 |
HIP 103808 |
12.05 |
| 2026-03-27 00:00 |
21:03:03.76 |
-21:19:37.6 |
HIP 103808 |
13.05 |
| 2026-03-27 12:00 |
21:03:08.00 |
-21:19:15.9 |
HIP 103927 |
13.47 |
| 2026-03-28 00:00 |
21:03:12.18 |
-21:18:54.5 |
HIP 103927 |
13.58 |
| 2026-03-28 12:00 |
21:03:16.32 |
-21:18:33.3 |
HIP 103927 |
13.77 |
| 2026-03-29 00:00 |
21:03:20.40 |
-21:18:12.4 |
HIP 103927 |
14.03 |
| 2026-03-29 12:00 |
21:03:24.42 |
-21:17:51.7 |
HIP 103927 |
14.35 |
| 2026-03-30 00:00 |
21:03:28.40 |
-21:17:31.3 |
HIP 103927 |
14.73 |
| 2026-03-30 12:00 |
21:03:32.31 |
-21:17:11.1 |
HIP 103927 |
15.15 |
| 2026-03-31 00:00 |
21:03:36.18 |
-21:16:51.2 |
HIP 103927 |
15.62 |
| 2026-03-31 12:00 |
21:03:39.99 |
-21:16:31.6 |
HIP 103927 |
16.12 |
| 2026-04-01 00:00 |
21:03:43.74 |
-21:16:12.3 |
HIP 103927 |
16.66 |
| 2026-04-01 12:00 |
21:03:47.43 |
-21:15:53.2 |
HIP 103927 |
17.22 |
| 2026-04-02 00:00 |
21:03:51.08 |
-21:15:34.3 |
HIP 103927 |
17.80 |
| 2026-04-02 12:00 |
21:03:54.66 |
-21:15:15.8 |
HIP 103927 |
18.39 |
| 2026-04-03 00:00 |
21:03:58.19 |
-21:14:57.5 |
HIP 103927 |
19.00 |
| 2026-04-03 12:00 |
21:04:01.66 |
-21:14:39.4 |
HIP 103927 |
19.62 |
| 2026-04-04 00:00 |
21:04:05.07 |
-21:14:21.7 |
HIP 103927 |
20.25 |
| 2026-04-04 12:00 |
21:04:08.43 |
-21:14:04.2 |
HIP 103927 |
20.89 |
| 2026-04-05 00:00 |
21:04:11.73 |
-21:13:47.0 |
HIP 103927 |
21.52 |
| 2026-04-05 12:00 |
21:04:14.97 |
-21:13:30.0 |
HIP 103927 |
22.16 |
| 2026-04-06 00:00 |
21:04:18.16 |
-21:13:13.3 |
HIP 103927 |
22.80 |
| 2026-04-06 12:00 |
21:04:21.28 |
-21:12:56.9 |
HIP 103927 |
23.43 |
| 2026-04-07 00:00 |
21:04:24.35 |
-21:12:40.8 |
HIP 103927 |
24.06 |
| 2026-04-07 12:00 |
21:04:27.35 |
-21:12:24.9 |
HIP 103927 |
24.69 |
| 2026-04-08 00:00 |
21:04:30.30 |
-21:12:09.4 |
HIP 103927 |
25.31 |
| 2026-04-08 12:00 |
21:04:33.19 |
-21:11:54.1 |
HIP 103927 |
25.93 |
| 2026-04-09 00:00 |
21:04:36.02 |
-21:11:39.0 |
HIP 103927 |
26.54 |
| 2026-04-09 12:00 |
21:04:38.78 |
-21:11:24.3 |
HIP 103927 |
27.14 |
| 2026-04-10 00:00 |
21:04:41.49 |
-21:11:09.8 |
HIP 103927 |
27.73 |
| 2026-04-10 12:00 |
21:04:44.14 |
-21:10:55.6 |
HIP 103927 |
28.31 |
| 2026-04-11 00:00 |
21:04:46.72 |
-21:10:41.7 |
HIP 103967 |
28.68 |
| 2026-04-11 12:00 |
21:04:49.24 |
-21:10:28.1 |
HIP 103967 |
28.74 |
| 2026-04-12 00:00 |
21:04:51.71 |
-21:10:14.8 |
HIP 103967 |
28.81 |
| 2026-04-12 12:00 |
21:04:54.11 |
-21:10:01.7 |
HIP 103967 |
28.89 |
| 2026-04-13 00:00 |
21:04:56.44 |
-21:09:49.0 |
HIP 103967 |
28.98 |
| 2026-04-13 12:00 |
21:04:58.72 |
-21:09:36.5 |
HIP 103967 |
29.08 |
| 2026-04-14 00:00 |
21:05:00.93 |
-21:09:24.3 |
HIP 103967 |
29.19 |
| 2026-04-14 12:00 |
21:05:03.08 |
-21:09:12.4 |
HIP 103967 |
29.30 |
| 2026-04-15 00:00 |
21:05:05.16 |
-21:09:00.7 |
HIP 103967 |
29.41 |
| 2026-04-15 12:00 |
21:05:07.18 |
-21:08:49.4 |
HIP 103967 |
29.53 |
| 2026-04-16 00:00 |
21:05:09.14 |
-21:08:38.4 |
HIP 103967 |
29.65 |