C/2021 J2 (PANSTARRS)
| Parameter |
Value |
| Designation |
C/2021 J2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-09-22T11:24:15.621120Z |
| Orbit solution date (soln_date, UTC) |
2023-12-06T01:14:09Z |
| Obs used |
218 |
| NEO |
- |
| M1 |
13.600 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-05-10T09:49:17.990400Z |
| Discovery magnitude (MPC) |
22.06 w |
| Discovery observatory (MPC) |
F51 · Pan-STARRS 1, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-02-01.0000000 |
| e |
0.95985091 |
| q (au) |
4.706567 |
| a (au) |
117.227257 |
| i (deg) |
156.209020 |
| Ω (om, deg) |
23.329370 |
| ω (w, deg) |
172.059356 |
| M (ma, deg) |
0.102134 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.688 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.688 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.612 |
| k |
0.800 |
| δ90 |
10.000 |
| 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 |
06:54:27.10 |
-02:46:56.5 |
HIP 33243 |
8.05 |
| 2026-02-03 12:00 |
06:54:15.24 |
-02:46:00.3 |
HIP 33243 |
11.13 |
| 2026-02-04 00:00 |
06:54:03.44 |
-02:45:03.7 |
HIP 33243 |
14.21 |
| 2026-02-04 12:00 |
06:53:51.70 |
-02:44:06.7 |
HIP 33243 |
17.28 |
| 2026-02-05 00:00 |
06:53:40.03 |
-02:43:09.4 |
HIP 33243 |
20.34 |
| 2026-02-05 12:00 |
06:53:28.42 |
-02:42:11.6 |
HIP 33014 |
18.09 |
| 2026-02-06 00:00 |
06:53:16.88 |
-02:41:13.5 |
HIP 33014 |
15.73 |
| 2026-02-06 12:00 |
06:53:05.41 |
-02:40:15.0 |
HIP 33014 |
13.63 |
| 2026-02-07 00:00 |
06:52:54.00 |
-02:39:16.1 |
HIP 33014 |
11.94 |
| 2026-02-07 12:00 |
06:52:42.67 |
-02:38:16.8 |
HIP 33014 |
10.82 |
| 2026-02-08 00:00 |
06:52:31.41 |
-02:37:17.2 |
HIP 33014 |
10.46 |
| 2026-02-08 12:00 |
06:52:20.21 |
-02:36:17.3 |
HIP 33014 |
10.93 |
| 2026-02-09 00:00 |
06:52:09.09 |
-02:35:17.0 |
HIP 33014 |
12.10 |
| 2026-02-09 12:00 |
06:51:58.04 |
-02:34:16.4 |
HIP 32936 |
10.95 |
| 2026-02-10 00:00 |
06:51:47.06 |
-02:33:15.4 |
HIP 32936 |
9.21 |
| 2026-02-10 12:00 |
06:51:36.15 |
-02:32:14.1 |
HIP 32936 |
8.17 |
| 2026-02-11 00:00 |
06:51:25.32 |
-02:31:12.5 |
HIP 32936 |
8.09 |
| 2026-02-11 12:00 |
06:51:14.57 |
-02:30:10.6 |
HIP 32936 |
8.97 |
| 2026-02-12 00:00 |
06:51:03.88 |
-02:29:08.3 |
HIP 32936 |
10.57 |
| 2026-02-12 12:00 |
06:50:53.28 |
-02:28:05.8 |
HIP 32936 |
12.60 |
| 2026-02-13 00:00 |
06:50:42.75 |
-02:27:02.9 |
HIP 32936 |
14.89 |
| 2026-02-13 12:00 |
06:50:32.30 |
-02:25:59.8 |
HIP 32936 |
17.31 |
| 2026-02-14 00:00 |
06:50:21.93 |
-02:24:56.4 |
HIP 32698 |
18.50 |
| 2026-02-14 12:00 |
06:50:11.63 |
-02:23:52.7 |
HIP 32698 |
15.73 |
| 2026-02-15 00:00 |
06:50:01.42 |
-02:22:48.7 |
HIP 32698 |
12.98 |
| 2026-02-15 12:00 |
06:49:51.28 |
-02:21:44.5 |
HIP 32698 |
10.26 |
| 2026-02-16 00:00 |
06:49:41.23 |
-02:20:40.0 |
HIP 32698 |
7.57 |
| 2026-02-16 12:00 |
06:49:31.26 |
-02:19:35.2 |
HIP 32698 |
4.94 |
| 2026-02-17 00:00 |
06:49:21.36 |
-02:18:30.2 |
HIP 32698 |
2.51 |
| 2026-02-17 12:00 |
06:49:11.55 |
-02:17:25.0 |
HIP 32698 |
1.63 |
| 2026-02-18 00:00 |
06:49:01.83 |
-02:16:19.5 |
HIP 32698 |
3.64 |
| 2026-02-18 12:00 |
06:48:52.18 |
-02:15:13.8 |
HIP 32698 |
6.15 |
| 2026-02-19 00:00 |
06:48:42.62 |
-02:14:07.9 |
HIP 32698 |
8.72 |
| 2026-02-19 12:00 |
06:48:33.15 |
-02:13:01.8 |
HIP 32698 |
11.30 |
| 2026-02-20 00:00 |
06:48:23.76 |
-02:11:55.4 |
HIP 32698 |
13.87 |
| 2026-02-20 12:00 |
06:48:14.45 |
-02:10:48.9 |
HIP 32698 |
16.43 |
| 2026-02-21 00:00 |
06:48:05.23 |
-02:09:42.1 |
HIP 32698 |
18.97 |
| 2026-02-21 12:00 |
06:47:56.10 |
-02:08:35.2 |
HIP 32624 |
20.56 |
| 2026-02-22 00:00 |
06:47:47.05 |
-02:07:28.0 |
HIP 32624 |
20.36 |
| 2026-02-22 12:00 |
06:47:38.09 |
-02:06:20.8 |
HIP 32624 |
20.46 |
| 2026-02-23 00:00 |
06:47:29.22 |
-02:05:13.3 |
HIP 32624 |
20.85 |
| 2026-02-23 12:00 |
06:47:20.43 |
-02:04:05.7 |
HIP 32624 |
21.50 |
| 2026-02-24 00:00 |
06:47:11.73 |
-02:02:57.9 |
HIP 32624 |
22.39 |