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) |
| 2026-07-29 00:00 |
20:49:20.87 |
-21:54:31.8 |
HIP 102743 |
16.86 |
| 2026-07-29 12:00 |
20:49:11.96 |
-21:54:55.0 |
HIP 102743 |
16.97 |
| 2026-07-30 00:00 |
20:49:03.05 |
-21:55:18.0 |
HIP 102743 |
17.33 |
| 2026-07-30 12:00 |
20:48:54.14 |
-21:55:41.0 |
HIP 102743 |
17.93 |
| 2026-07-31 00:00 |
20:48:45.22 |
-21:56:03.9 |
HIP 102743 |
18.75 |
| 2026-07-31 12:00 |
20:48:36.31 |
-21:56:26.6 |
HIP 102743 |
19.75 |
| 2026-08-01 00:00 |
20:48:27.39 |
-21:56:49.3 |
HIP 102743 |
20.92 |
| 2026-08-01 12:00 |
20:48:18.48 |
-21:57:11.9 |
HIP 102743 |
22.23 |
| 2026-08-02 00:00 |
20:48:09.57 |
-21:57:34.3 |
HIP 102743 |
23.64 |
| 2026-08-02 12:00 |
20:48:00.66 |
-21:57:56.7 |
HIP 102512 |
24.11 |
| 2026-08-03 00:00 |
20:47:51.75 |
-21:58:18.9 |
HIP 102512 |
22.14 |
| 2026-08-03 12:00 |
20:47:42.84 |
-21:58:41.0 |
HIP 102512 |
20.20 |
| 2026-08-04 00:00 |
20:47:33.95 |
-21:59:03.0 |
HIP 102512 |
18.30 |
| 2026-08-04 12:00 |
20:47:25.05 |
-21:59:24.9 |
HIP 102512 |
16.44 |
| 2026-08-05 00:00 |
20:47:16.16 |
-21:59:46.7 |
HIP 102512 |
14.66 |
| 2026-08-05 12:00 |
20:47:07.28 |
-22:00:08.3 |
HIP 102512 |
12.96 |
| 2026-08-06 00:00 |
20:46:58.41 |
-22:00:29.8 |
HIP 102512 |
11.41 |
| 2026-08-06 12:00 |
20:46:49.54 |
-22:00:51.2 |
HIP 102512 |
10.04 |
| 2026-08-07 00:00 |
20:46:40.68 |
-22:01:12.4 |
HIP 102512 |
8.97 |
| 2026-08-07 12:00 |
20:46:31.83 |
-22:01:33.5 |
HIP 102512 |
8.28 |
| 2026-08-08 00:00 |
20:46:22.99 |
-22:01:54.5 |
HIP 102512 |
8.09 |
| 2026-08-08 12:00 |
20:46:14.17 |
-22:02:15.4 |
HIP 102512 |
8.43 |
| 2026-08-09 00:00 |
20:46:05.35 |
-22:02:36.0 |
HIP 102512 |
9.23 |
| 2026-08-09 12:00 |
20:45:56.55 |
-22:02:56.6 |
HIP 102512 |
10.39 |
| 2026-08-10 00:00 |
20:45:47.76 |
-22:03:17.0 |
HIP 102512 |
11.80 |
| 2026-08-10 12:00 |
20:45:38.98 |
-22:03:37.3 |
HIP 102512 |
13.38 |
| 2026-08-11 00:00 |
20:45:30.22 |
-22:03:57.4 |
HIP 102512 |
15.07 |
| 2026-08-11 12:00 |
20:45:21.47 |
-22:04:17.3 |
HIP 102512 |
16.84 |
| 2026-08-12 00:00 |
20:45:12.74 |
-22:04:37.1 |
HIP 102512 |
18.67 |
| 2026-08-12 12:00 |
20:45:04.03 |
-22:04:56.7 |
HIP 102512 |
20.53 |
| 2026-08-13 00:00 |
20:44:55.33 |
-22:05:16.2 |
HIP 102512 |
22.42 |
| 2026-08-13 12:00 |
20:44:46.66 |
-22:05:35.5 |
HIP 102251 |
24.23 |
| 2026-08-14 00:00 |
20:44:38.00 |
-22:05:54.7 |
HIP 102251 |
22.46 |
| 2026-08-14 12:00 |
20:44:29.36 |
-22:06:13.6 |
HIP 102251 |
20.73 |
| 2026-08-15 00:00 |
20:44:20.75 |
-22:06:32.4 |
HIP 102251 |
19.07 |
| 2026-08-15 12:00 |
20:44:12.15 |
-22:06:51.1 |
HIP 102251 |
17.49 |
| 2026-08-16 00:00 |
20:44:03.58 |
-22:07:09.5 |
HIP 102251 |
16.00 |
| 2026-08-16 12:00 |
20:43:55.03 |
-22:07:27.8 |
HIP 102251 |
14.64 |
| 2026-08-17 00:00 |
20:43:46.50 |
-22:07:45.9 |
HIP 102251 |
13.45 |
| 2026-08-17 12:00 |
20:43:38.00 |
-22:08:03.8 |
HIP 102251 |
12.47 |
| 2026-08-18 00:00 |
20:43:29.53 |
-22:08:21.5 |
HIP 102251 |
11.75 |
| 2026-08-18 12:00 |
20:43:21.08 |
-22:08:39.1 |
HIP 102251 |
11.33 |
| 2026-08-19 00:00 |
20:43:12.65 |
-22:08:56.5 |
HIP 102251 |
11.24 |