C/2021 R7 (PANSTARRS)
| 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) |
| 2026-02-03 00:00 |
20:09:44.42 |
-36:52:04.9 |
HIP 99368 |
13.69 |
| 2026-02-03 12:00 |
20:09:52.25 |
-36:52:03.1 |
HIP 99368 |
13.19 |
| 2026-02-04 00:00 |
20:10:00.05 |
-36:52:01.5 |
HIP 99368 |
12.86 |
| 2026-02-04 12:00 |
20:10:07.83 |
-36:52:00.3 |
HIP 99368 |
12.72 |
| 2026-02-05 00:00 |
20:10:15.58 |
-36:51:59.5 |
HIP 99368 |
12.77 |
| 2026-02-05 12:00 |
20:10:23.31 |
-36:51:59.0 |
HIP 99368 |
13.02 |
| 2026-02-06 00:00 |
20:10:31.02 |
-36:51:58.9 |
HIP 99368 |
13.45 |
| 2026-02-06 12:00 |
20:10:38.70 |
-36:51:59.1 |
HIP 99368 |
14.04 |
| 2026-02-07 00:00 |
20:10:46.35 |
-36:51:59.7 |
HIP 99368 |
14.76 |
| 2026-02-07 12:00 |
20:10:53.97 |
-36:52:00.6 |
HIP 99368 |
15.61 |
| 2026-02-08 00:00 |
20:11:01.57 |
-36:52:01.9 |
HIP 99368 |
16.55 |
| 2026-02-08 12:00 |
20:11:09.14 |
-36:52:03.6 |
HIP 99368 |
17.58 |
| 2026-02-09 00:00 |
20:11:16.68 |
-36:52:05.6 |
HIP 99368 |
18.67 |
| 2026-02-09 12:00 |
20:11:24.19 |
-36:52:08.0 |
HIP 99368 |
19.82 |
| 2026-02-10 00:00 |
20:11:31.68 |
-36:52:10.7 |
HIP 99368 |
21.01 |
| 2026-02-10 12:00 |
20:11:39.13 |
-36:52:13.8 |
HIP 99368 |
22.24 |
| 2026-02-11 00:00 |
20:11:46.55 |
-36:52:17.3 |
HIP 99368 |
23.50 |
| 2026-02-11 12:00 |
20:11:53.93 |
-36:52:21.2 |
HIP 99368 |
24.78 |
| 2026-02-12 00:00 |
20:12:01.29 |
-36:52:25.4 |
HIP 99368 |
26.07 |
| 2026-02-12 12:00 |
20:12:08.61 |
-36:52:30.0 |
HIP 99368 |
27.39 |
| 2026-02-13 00:00 |
20:12:15.89 |
-36:52:34.9 |
HIP 99718 |
26.82 |
| 2026-02-13 12:00 |
20:12:23.14 |
-36:52:40.3 |
HIP 99718 |
25.71 |
| 2026-02-14 00:00 |
20:12:30.36 |
-36:52:46.0 |
HIP 99718 |
24.65 |
| 2026-02-14 12:00 |
20:12:37.54 |
-36:52:52.1 |
HIP 99718 |
23.63 |
| 2026-02-15 00:00 |
20:12:44.68 |
-36:52:58.6 |
HIP 99718 |
22.67 |
| 2026-02-15 12:00 |
20:12:51.78 |
-36:53:05.4 |
HIP 99718 |
21.78 |
| 2026-02-16 00:00 |
20:12:58.85 |
-36:53:12.7 |
HIP 99718 |
20.95 |
| 2026-02-16 12:00 |
20:13:05.88 |
-36:53:20.3 |
HIP 99718 |
20.20 |
| 2026-02-17 00:00 |
20:13:12.87 |
-36:53:28.3 |
HIP 99718 |
19.53 |
| 2026-02-17 12:00 |
20:13:19.81 |
-36:53:36.7 |
HIP 99718 |
18.96 |
| 2026-02-18 00:00 |
20:13:26.72 |
-36:53:45.5 |
HIP 99718 |
18.48 |
| 2026-02-18 12:00 |
20:13:33.59 |
-36:53:54.7 |
HIP 99718 |
18.10 |
| 2026-02-19 00:00 |
20:13:40.41 |
-36:54:04.2 |
HIP 99718 |
17.83 |
| 2026-02-19 12:00 |
20:13:47.19 |
-36:54:14.2 |
HIP 99718 |
17.68 |
| 2026-02-20 00:00 |
20:13:53.92 |
-36:54:24.5 |
HIP 99718 |
17.63 |
| 2026-02-20 12:00 |
20:14:00.62 |
-36:54:35.3 |
HIP 99718 |
17.70 |
| 2026-02-21 00:00 |
20:14:07.26 |
-36:54:46.4 |
HIP 99718 |
17.88 |
| 2026-02-21 12:00 |
20:14:13.86 |
-36:54:58.0 |
HIP 99718 |
18.16 |
| 2026-02-22 00:00 |
20:14:20.42 |
-36:55:09.9 |
HIP 99718 |
18.54 |
| 2026-02-22 12:00 |
20:14:26.93 |
-36:55:22.3 |
HIP 99718 |
19.00 |
| 2026-02-23 00:00 |
20:14:33.39 |
-36:55:35.0 |
HIP 99718 |
19.55 |
| 2026-02-23 12:00 |
20:14:39.80 |
-36:55:48.1 |
HIP 99718 |
20.17 |
| 2026-02-24 00:00 |
20:14:46.16 |
-36:56:01.7 |
HIP 99718 |
20.86 |