| 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) |
| 2026-09-20 00:00 |
07:03:30.28 |
-00:23:50.4 |
HIP 34039 |
9.99 |
| 2026-09-20 12:00 |
07:03:30.58 |
-00:24:39.0 |
HIP 34039 |
9.19 |
| 2026-09-21 00:00 |
07:03:30.80 |
-00:25:27.8 |
HIP 34039 |
8.40 |
| 2026-09-21 12:00 |
07:03:30.96 |
-00:26:16.5 |
HIP 34039 |
7.63 |
| 2026-09-22 00:00 |
07:03:31.04 |
-00:27:05.4 |
HIP 34039 |
6.86 |
| 2026-09-22 12:00 |
07:03:31.05 |
-00:27:54.3 |
HIP 34039 |
6.12 |
| 2026-09-23 00:00 |
07:03:30.99 |
-00:28:43.2 |
HIP 34039 |
5.40 |
| 2026-09-23 12:00 |
07:03:30.86 |
-00:29:32.2 |
HIP 34039 |
4.73 |
| 2026-09-24 00:00 |
07:03:30.65 |
-00:30:21.2 |
HIP 34039 |
4.12 |
| 2026-09-24 12:00 |
07:03:30.37 |
-00:31:10.2 |
HIP 34039 |
3.61 |
| 2026-09-25 00:00 |
07:03:30.02 |
-00:31:59.3 |
HIP 34039 |
3.24 |
| 2026-09-25 12:00 |
07:03:29.59 |
-00:32:48.4 |
HIP 34039 |
3.08 |
| 2026-09-26 00:00 |
07:03:29.09 |
-00:33:37.6 |
HIP 34039 |
3.15 |
| 2026-09-26 12:00 |
07:03:28.51 |
-00:34:26.7 |
HIP 34039 |
3.44 |
| 2026-09-27 00:00 |
07:03:27.86 |
-00:35:15.9 |
HIP 34039 |
3.91 |
| 2026-09-27 12:00 |
07:03:27.13 |
-00:36:05.1 |
HIP 34039 |
4.51 |
| 2026-09-28 00:00 |
07:03:26.33 |
-00:36:54.3 |
HIP 34039 |
5.18 |
| 2026-09-28 12:00 |
07:03:25.46 |
-00:37:43.5 |
HIP 34039 |
5.91 |
| 2026-09-29 00:00 |
07:03:24.51 |
-00:38:32.7 |
HIP 34039 |
6.68 |
| 2026-09-29 12:00 |
07:03:23.48 |
-00:39:21.9 |
HIP 34039 |
7.48 |
| 2026-09-30 00:00 |
07:03:22.38 |
-00:40:11.1 |
HIP 34039 |
8.31 |
| 2026-09-30 12:00 |
07:03:21.20 |
-00:41:00.3 |
HIP 34039 |
9.15 |
| 2026-10-01 00:00 |
07:03:19.94 |
-00:41:49.4 |
HIP 34039 |
10.01 |
| 2026-10-01 12:00 |
07:03:18.61 |
-00:42:38.6 |
HIP 34039 |
10.88 |
| 2026-10-02 00:00 |
07:03:17.20 |
-00:43:27.8 |
HIP 34039 |
11.76 |
| 2026-10-02 12:00 |
07:03:15.71 |
-00:44:16.9 |
HIP 34039 |
12.65 |
| 2026-10-03 00:00 |
07:03:14.15 |
-00:45:06.0 |
HIP 34039 |
13.56 |
| 2026-10-03 12:00 |
07:03:12.51 |
-00:45:55.1 |
HIP 34039 |
14.47 |
| 2026-10-04 00:00 |
07:03:10.79 |
-00:46:44.1 |
HIP 34039 |
15.39 |
| 2026-10-04 12:00 |
07:03:09.00 |
-00:47:33.1 |
HIP 34039 |
16.32 |
| 2026-10-05 00:00 |
07:03:07.12 |
-00:48:22.1 |
HIP 34039 |
17.26 |
| 2026-10-05 12:00 |
07:03:05.17 |
-00:49:11.0 |
HIP 34039 |
18.21 |
| 2026-10-06 00:00 |
07:03:03.13 |
-00:49:59.9 |
HIP 34039 |
19.17 |
| 2026-10-06 12:00 |
07:03:01.02 |
-00:50:48.7 |
HIP 34049 |
19.11 |
| 2026-10-07 00:00 |
07:02:58.83 |
-00:51:37.4 |
HIP 34049 |
18.82 |
| 2026-10-07 12:00 |
07:02:56.56 |
-00:52:26.1 |
HIP 34049 |
18.59 |
| 2026-10-08 00:00 |
07:02:54.22 |
-00:53:14.7 |
HIP 34049 |
18.43 |
| 2026-10-08 12:00 |
07:02:51.79 |
-00:54:03.3 |
HIP 34049 |
18.34 |
| 2026-10-09 00:00 |
07:02:49.28 |
-00:54:51.7 |
HIP 34049 |
18.32 |
| 2026-10-09 12:00 |
07:02:46.69 |
-00:55:40.1 |
HIP 33874 |
18.02 |
| 2026-10-10 00:00 |
07:02:44.02 |
-00:56:28.4 |
HIP 33874 |
16.98 |
| 2026-10-10 12:00 |
07:02:41.27 |
-00:57:16.6 |
HIP 33874 |
15.93 |
| 2026-10-11 00:00 |
07:02:38.45 |
-00:58:04.7 |
HIP 33874 |
14.87 |