| Parameter |
Value |
| Designation |
C/2021 R7 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-04-14T11:28:22.085760Z |
| Orbit solution date (soln_date, UTC) |
2022-12-08T23:43:02Z |
| Obs used |
63 |
| NEO |
- |
| M1 |
7.700 |
| K1 |
14.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-09-05T10:13:05.577600Z |
| Discovery magnitude (MPC) |
22.01 w |
| Discovery observatory (MPC) |
F52 · Pan-STARRS 2, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-11-23.0000000 |
| e |
0.99519043 |
| q (au) |
5.640615 |
| a (au) |
1172.790949 |
| i (deg) |
158.854146 |
| Ω (om, deg) |
170.145186 |
| ω (w, deg) |
139.994299 |
| M (ma, deg) |
0.005461 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.384 + 5.410\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.384 |
| n |
5.410 |
| gf |
0.999 |
| gb |
-0.856 |
| k |
1.000 |
| 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) |
| 2026-05-12 00:00 |
20:16:18.89 |
-38:48:34.3 |
HIP 100033 |
24.54 |
| 2026-05-12 12:00 |
20:16:12.29 |
-38:49:42.0 |
HIP 100033 |
24.63 |
| 2026-05-13 00:00 |
20:16:05.58 |
-38:50:49.8 |
HIP 100033 |
24.84 |
| 2026-05-13 12:00 |
20:15:58.77 |
-38:51:57.8 |
HIP 100033 |
25.19 |
| 2026-05-14 00:00 |
20:15:51.86 |
-38:53:05.8 |
HIP 100033 |
25.66 |
| 2026-05-14 12:00 |
20:15:44.86 |
-38:54:14.0 |
HIP 100033 |
26.26 |
| 2026-05-15 00:00 |
20:15:37.75 |
-38:55:22.3 |
HIP 100033 |
26.98 |
| 2026-05-15 12:00 |
20:15:30.54 |
-38:56:30.7 |
HIP 100033 |
27.81 |
| 2026-05-16 00:00 |
20:15:23.22 |
-38:57:39.2 |
HIP 100033 |
28.75 |
| 2026-05-16 12:00 |
20:15:15.81 |
-38:58:47.9 |
HIP 100033 |
29.79 |
| 2026-05-17 00:00 |
20:15:08.30 |
-38:59:56.6 |
HIP 100033 |
30.92 |
| 2026-05-17 12:00 |
20:15:00.69 |
-39:01:05.4 |
HIP 99886 |
30.33 |
| 2026-05-18 00:00 |
20:14:52.98 |
-39:02:14.2 |
HIP 99886 |
29.85 |
| 2026-05-18 12:00 |
20:14:45.17 |
-39:03:23.2 |
HIP 99886 |
29.48 |
| 2026-05-19 00:00 |
20:14:37.27 |
-39:04:32.2 |
HIP 99886 |
29.25 |
| 2026-05-19 12:00 |
20:14:29.26 |
-39:05:41.3 |
HIP 99886 |
29.15 |
| 2026-05-20 00:00 |
20:14:21.16 |
-39:06:50.4 |
HIP 99886 |
29.19 |
| 2026-05-20 12:00 |
20:14:12.95 |
-39:07:59.6 |
HIP 99612 |
29.06 |
| 2026-05-21 00:00 |
20:14:04.65 |
-39:09:08.8 |
HIP 99612 |
27.25 |
| 2026-05-21 12:00 |
20:13:56.26 |
-39:10:18.1 |
HIP 99612 |
25.46 |
| 2026-05-22 00:00 |
20:13:47.76 |
-39:11:27.4 |
HIP 99612 |
23.69 |
| 2026-05-22 12:00 |
20:13:39.17 |
-39:12:36.8 |
HIP 99612 |
21.96 |
| 2026-05-23 00:00 |
20:13:30.49 |
-39:13:46.1 |
HIP 99612 |
20.28 |
| 2026-05-23 12:00 |
20:13:21.71 |
-39:14:55.5 |
HIP 99612 |
18.66 |
| 2026-05-24 00:00 |
20:13:12.83 |
-39:16:04.9 |
HIP 99612 |
17.13 |
| 2026-05-24 12:00 |
20:13:03.86 |
-39:17:14.3 |
HIP 99612 |
15.72 |
| 2026-05-25 00:00 |
20:12:54.80 |
-39:18:23.7 |
HIP 99612 |
14.48 |
| 2026-05-25 12:00 |
20:12:45.64 |
-39:19:33.0 |
HIP 99612 |
13.45 |
| 2026-05-26 00:00 |
20:12:36.39 |
-39:20:42.4 |
HIP 99612 |
12.70 |
| 2026-05-26 12:00 |
20:12:27.04 |
-39:21:51.8 |
HIP 99612 |
12.29 |
| 2026-05-27 00:00 |
20:12:17.60 |
-39:23:01.1 |
HIP 99612 |
12.25 |
| 2026-05-27 12:00 |
20:12:08.07 |
-39:24:10.4 |
HIP 99463 |
10.60 |
| 2026-05-28 00:00 |
20:11:58.45 |
-39:25:19.6 |
HIP 99463 |
8.64 |
| 2026-05-28 12:00 |
20:11:48.74 |
-39:26:28.8 |
HIP 99463 |
6.79 |
| 2026-05-29 00:00 |
20:11:38.94 |
-39:27:38.0 |
HIP 99463 |
5.22 |
| 2026-05-29 12:00 |
20:11:29.04 |
-39:28:47.1 |
HIP 99463 |
4.25 |
| 2026-05-30 00:00 |
20:11:19.06 |
-39:29:56.2 |
HIP 99463 |
4.33 |
| 2026-05-30 12:00 |
20:11:08.98 |
-39:31:05.2 |
HIP 99463 |
5.44 |
| 2026-05-31 00:00 |
20:10:58.82 |
-39:32:14.1 |
HIP 99463 |
7.12 |
| 2026-05-31 12:00 |
20:10:48.57 |
-39:33:22.9 |
HIP 99463 |
9.07 |
| 2026-06-01 00:00 |
20:10:38.23 |
-39:34:31.7 |
HIP 99463 |
11.16 |
| 2026-06-01 12:00 |
20:10:27.81 |
-39:35:40.3 |
HIP 99463 |
13.32 |
| 2026-06-02 00:00 |
20:10:17.30 |
-39:36:48.9 |
HIP 99463 |
15.54 |