P/2021 R1 (PANSTARRS)
| Parameter |
Value |
| Designation |
P/2021 R1 (PANSTARRS) |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2021-12-17T19:36:46.062720Z |
| Orbit solution date (soln_date, UTC) |
2022-12-08T23:43:17Z |
| Obs used |
127 |
| NEO |
- |
| M1 |
7.500 |
| K1 |
15.250 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-09-04T08:31:35.241600Z |
| Discovery magnitude (MPC) |
20.60 w |
| Discovery observatory (MPC) |
F51 · Pan-STARRS 1, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-02-25.0000000 |
| e |
0.41886575 |
| q (au) |
4.885582 |
| a (au) |
8.406977 |
| i (deg) |
5.521079 |
| Ω (om, deg) |
143.406228 |
| ω (w, deg) |
220.343748 |
| M (ma, deg) |
2.797322 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.514 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.514 |
| n |
6.000 |
| gf |
0.923 |
| gb |
-0.916 |
| k |
1.000 |
| δ90 |
1.000 |
| 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 |
07:30:17.45 |
+18:44:24.8 |
HIP 36449 |
7.67 |
| 2026-02-03 12:00 |
07:30:07.06 |
+18:44:59.7 |
HIP 36449 |
7.35 |
| 2026-02-04 00:00 |
07:29:56.74 |
+18:45:34.5 |
HIP 36449 |
7.87 |
| 2026-02-04 12:00 |
07:29:46.49 |
+18:46:09.1 |
HIP 36449 |
9.07 |
| 2026-02-05 00:00 |
07:29:36.32 |
+18:46:43.7 |
HIP 36449 |
10.72 |
| 2026-02-05 12:00 |
07:29:26.23 |
+18:47:18.1 |
HIP 36449 |
12.62 |
| 2026-02-06 00:00 |
07:29:16.21 |
+18:47:52.4 |
HIP 36449 |
14.68 |
| 2026-02-06 12:00 |
07:29:06.27 |
+18:48:26.7 |
HIP 36449 |
16.82 |
| 2026-02-07 00:00 |
07:28:56.41 |
+18:49:00.7 |
HIP 36449 |
19.01 |
| 2026-02-07 12:00 |
07:28:46.63 |
+18:49:34.7 |
HIP 36249 |
18.63 |
| 2026-02-08 00:00 |
07:28:36.93 |
+18:50:08.5 |
HIP 36249 |
16.65 |
| 2026-02-08 12:00 |
07:28:27.32 |
+18:50:42.2 |
HIP 36249 |
14.79 |
| 2026-02-09 00:00 |
07:28:17.80 |
+18:51:15.8 |
HIP 36249 |
13.11 |
| 2026-02-09 12:00 |
07:28:08.36 |
+18:51:49.3 |
HIP 36249 |
11.65 |
| 2026-02-10 00:00 |
07:27:59.01 |
+18:52:22.6 |
HIP 36249 |
10.51 |
| 2026-02-10 12:00 |
07:27:49.75 |
+18:52:55.7 |
HIP 36249 |
9.77 |
| 2026-02-11 00:00 |
07:27:40.57 |
+18:53:28.7 |
HIP 36249 |
9.53 |
| 2026-02-11 12:00 |
07:27:31.49 |
+18:54:01.6 |
HIP 36249 |
9.79 |
| 2026-02-12 00:00 |
07:27:22.51 |
+18:54:34.3 |
HIP 36249 |
10.51 |
| 2026-02-12 12:00 |
07:27:13.62 |
+18:55:06.9 |
HIP 36174 |
11.16 |
| 2026-02-13 00:00 |
07:27:04.82 |
+18:55:39.3 |
HIP 36174 |
10.32 |
| 2026-02-13 12:00 |
07:26:56.12 |
+18:56:11.5 |
HIP 36174 |
9.88 |
| 2026-02-14 00:00 |
07:26:47.52 |
+18:56:43.6 |
HIP 36174 |
9.88 |
| 2026-02-14 12:00 |
07:26:39.01 |
+18:57:15.5 |
HIP 36174 |
10.30 |
| 2026-02-15 00:00 |
07:26:30.61 |
+18:57:47.3 |
HIP 36174 |
11.09 |
| 2026-02-15 12:00 |
07:26:22.31 |
+18:58:18.9 |
HIP 36174 |
12.17 |
| 2026-02-16 00:00 |
07:26:14.11 |
+18:58:50.3 |
HIP 36174 |
13.44 |
| 2026-02-16 12:00 |
07:26:06.01 |
+18:59:21.5 |
HIP 36000 |
13.33 |
| 2026-02-17 00:00 |
07:25:58.02 |
+18:59:52.6 |
HIP 36000 |
11.41 |
| 2026-02-17 12:00 |
07:25:50.13 |
+19:00:23.5 |
HIP 36000 |
9.54 |
| 2026-02-18 00:00 |
07:25:42.35 |
+19:00:54.2 |
HIP 36000 |
7.72 |
| 2026-02-18 12:00 |
07:25:34.68 |
+19:01:24.7 |
HIP 36000 |
5.98 |
| 2026-02-19 00:00 |
07:25:27.12 |
+19:01:55.0 |
HIP 36000 |
4.39 |
| 2026-02-19 12:00 |
07:25:19.67 |
+19:02:25.2 |
HIP 36000 |
3.13 |
| 2026-02-20 00:00 |
07:25:12.32 |
+19:02:55.1 |
HIP 36000 |
2.66 |
| 2026-02-20 12:00 |
07:25:05.09 |
+19:03:24.9 |
HIP 36000 |
3.28 |
| 2026-02-21 00:00 |
07:24:57.97 |
+19:03:54.4 |
HIP 36000 |
4.54 |
| 2026-02-21 12:00 |
07:24:50.97 |
+19:04:23.8 |
HIP 36000 |
6.03 |
| 2026-02-22 00:00 |
07:24:44.07 |
+19:04:53.0 |
HIP 36000 |
7.59 |
| 2026-02-22 12:00 |
07:24:37.30 |
+19:05:21.9 |
HIP 36000 |
9.18 |
| 2026-02-23 00:00 |
07:24:30.64 |
+19:05:50.7 |
HIP 36000 |
10.77 |
| 2026-02-23 12:00 |
07:24:24.09 |
+19:06:19.2 |
HIP 35928 |
11.70 |
| 2026-02-24 00:00 |
07:24:17.66 |
+19:06:47.5 |
HIP 35928 |
12.28 |