메타데이터
| 항목 |
값 |
| Designation |
C/2021 A2 (NEOWISE) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-01-22T15:13:06.119040Z |
| Orbit solution date (soln_date, UTC) |
2025-01-02T20:12:26Z |
| Obs used |
980 |
| NEO |
- |
| M1 |
15.000 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-01-03T00:31:00.192000Z |
| Discovery magnitude (MPC) |
15.00 R |
| Discovery observatory (MPC) |
C51 · WISE |
Osculating 궤도요소
| 항목 |
값 |
| Epoch (epoch_cal, TDB) |
2021-02-20.0000000 |
| e |
0.99451672 |
| q (au) |
1.412974 |
| a (au) |
257.687917 |
| i (deg) |
106.978275 |
| Ω (om, deg) |
125.238283 |
| ω (w, deg) |
338.849015 |
| M (ma, deg) |
0.006759 |
밝기
산란 + 전체 선형
$$
M_a = (14.158 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
모델 상수
| 항목 |
값 |
| H0 |
14.158 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.991 |
| 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 |
| 2021-01-23 |
2021-05-09 |
+4.2062 |
-1.270 |
log10 r = log10(태양거리/AU), Δ = 지구거리(AU)
천체력
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
20:42:55.91 |
+39:05:32.6 |
HIP 102234 |
4.12 |
| 2026-07-29 12:00 |
20:42:46.52 |
+39:05:06.5 |
HIP 102234 |
4.15 |
| 2026-07-30 00:00 |
20:42:37.14 |
+39:04:39.5 |
HIP 102234 |
4.94 |
| 2026-07-30 12:00 |
20:42:27.75 |
+39:04:11.7 |
HIP 102234 |
6.21 |
| 2026-07-31 00:00 |
20:42:18.37 |
+39:03:43.1 |
HIP 102234 |
7.73 |
| 2026-07-31 12:00 |
20:42:08.99 |
+39:03:13.6 |
HIP 102234 |
9.38 |
| 2026-08-01 00:00 |
20:41:59.61 |
+39:02:43.3 |
HIP 102234 |
11.10 |
| 2026-08-01 12:00 |
20:41:50.24 |
+39:02:12.1 |
HIP 102062 |
10.06 |
| 2026-08-02 00:00 |
20:41:40.87 |
+39:01:40.1 |
HIP 102062 |
8.52 |
| 2026-08-02 12:00 |
20:41:31.51 |
+39:01:07.2 |
HIP 102062 |
7.15 |
| 2026-08-03 00:00 |
20:41:22.15 |
+39:00:33.6 |
HIP 102062 |
6.09 |
| 2026-08-03 12:00 |
20:41:12.80 |
+38:59:59.0 |
HIP 102062 |
5.51 |
| 2026-08-04 00:00 |
20:41:03.46 |
+38:59:23.7 |
HIP 102062 |
5.58 |
| 2026-08-04 12:00 |
20:40:54.12 |
+38:58:47.5 |
HIP 102062 |
6.27 |
| 2026-08-05 00:00 |
20:40:44.80 |
+38:58:10.5 |
HIP 102062 |
7.41 |
| 2026-08-05 12:00 |
20:40:35.48 |
+38:57:32.7 |
HIP 102062 |
8.83 |
| 2026-08-06 00:00 |
20:40:26.18 |
+38:56:54.0 |
HIP 102016 |
10.14 |
| 2026-08-06 12:00 |
20:40:16.89 |
+38:56:14.5 |
HIP 102016 |
9.46 |
| 2026-08-07 00:00 |
20:40:07.61 |
+38:55:34.2 |
HIP 102016 |
9.13 |
| 2026-08-07 12:00 |
20:39:58.34 |
+38:54:53.1 |
HIP 102016 |
9.18 |
| 2026-08-08 00:00 |
20:39:49.09 |
+38:54:11.1 |
HIP 101970 |
8.73 |
| 2026-08-08 12:00 |
20:39:39.85 |
+38:53:28.3 |
HIP 101970 |
8.44 |
| 2026-08-09 00:00 |
20:39:30.63 |
+38:52:44.7 |
HIP 101970 |
8.57 |
| 2026-08-09 12:00 |
20:39:21.42 |
+38:52:00.3 |
HIP 101970 |
9.12 |
| 2026-08-10 00:00 |
20:39:12.24 |
+38:51:15.1 |
HIP 101970 |
10.00 |
| 2026-08-10 12:00 |
20:39:03.07 |
+38:50:29.1 |
HIP 101970 |
11.14 |
| 2026-08-11 00:00 |
20:38:53.92 |
+38:49:42.3 |
HIP 101875 |
11.88 |
| 2026-08-11 12:00 |
20:38:44.79 |
+38:48:54.7 |
HIP 101875 |
10.82 |
| 2026-08-12 00:00 |
20:38:35.68 |
+38:48:06.2 |
HIP 101875 |
10.01 |
| 2026-08-12 12:00 |
20:38:26.59 |
+38:47:17.0 |
HIP 101875 |
9.52 |
| 2026-08-13 00:00 |
20:38:17.53 |
+38:46:27.0 |
HIP 101875 |
9.40 |
| 2026-08-13 12:00 |
20:38:08.49 |
+38:45:36.2 |
HIP 101875 |
9.68 |
| 2026-08-14 00:00 |
20:37:59.47 |
+38:44:44.6 |
HIP 101875 |
10.31 |
| 2026-08-14 12:00 |
20:37:50.48 |
+38:43:52.3 |
HIP 101875 |
11.25 |
| 2026-08-15 00:00 |
20:37:41.51 |
+38:42:59.1 |
HIP 101875 |
12.41 |
| 2026-08-15 12:00 |
20:37:32.57 |
+38:42:05.2 |
HIP 101875 |
13.75 |
| 2026-08-16 00:00 |
20:37:23.66 |
+38:41:10.5 |
HIP 101875 |
15.22 |
| 2026-08-16 12:00 |
20:37:14.78 |
+38:40:15.1 |
HIP 101875 |
16.78 |
| 2026-08-17 00:00 |
20:37:05.93 |
+38:39:18.9 |
HIP 101723 |
18.00 |
| 2026-08-17 12:00 |
20:36:57.10 |
+38:38:22.0 |
HIP 101723 |
19.11 |
| 2026-08-18 00:00 |
20:36:48.31 |
+38:37:24.3 |
HIP 101756 |
18.98 |
| 2026-08-18 12:00 |
20:36:39.55 |
+38:36:25.8 |
HIP 101756 |
18.80 |
| 2026-08-19 00:00 |
20:36:30.82 |
+38:35:26.6 |
HIP 101756 |
18.81 |