| Parameter |
Value |
| Designation |
C/2021 R2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-12-25T00:02:41.040960Z |
| Orbit solution date (soln_date, UTC) |
2022-12-08T23:43:01Z |
| Obs used |
126 |
| NEO |
- |
| M1 |
7.000 |
| K1 |
10.750 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-09-05T08:07:54.134400Z |
| Discovery magnitude (MPC) |
20.48 w |
| Discovery observatory (MPC) |
F52 · Pan-STARRS 2, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-11-08.0000000 |
| e |
0.99748693 |
| q (au) |
7.311968 |
| a (au) |
2909.581318 |
| i (deg) |
134.470894 |
| Ω (om, deg) |
16.283615 |
| ω (w, deg) |
32.298315 |
| M (ma, deg) |
359.999705 |
Magnitude
Scatter + Global Linear
$$
M_a = (2.347 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
2.347 |
| n |
6.000 |
| gf |
0.997 |
| gb |
-0.500 |
| 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 |
17:35:09.29 |
+21:41:54.1 |
HIP 85942 |
19.02 |
| 2026-05-12 12:00 |
17:34:56.58 |
+21:42:45.1 |
HIP 85942 |
16.82 |
| 2026-05-13 00:00 |
17:34:43.82 |
+21:43:35.3 |
HIP 85942 |
14.91 |
| 2026-05-13 12:00 |
17:34:31.01 |
+21:44:24.7 |
HIP 85942 |
13.43 |
| 2026-05-14 00:00 |
17:34:18.14 |
+21:45:13.2 |
HIP 85942 |
12.52 |
| 2026-05-14 12:00 |
17:34:05.21 |
+21:46:01.0 |
HIP 85942 |
12.34 |
| 2026-05-15 00:00 |
17:33:52.23 |
+21:46:47.9 |
HIP 85942 |
12.91 |
| 2026-05-15 12:00 |
17:33:39.21 |
+21:47:33.9 |
HIP 85873 |
12.02 |
| 2026-05-16 00:00 |
17:33:26.13 |
+21:48:19.2 |
HIP 85873 |
9.00 |
| 2026-05-16 12:00 |
17:33:13.00 |
+21:49:03.5 |
HIP 85873 |
6.08 |
| 2026-05-17 00:00 |
17:32:59.82 |
+21:49:47.0 |
HIP 85873 |
3.56 |
| 2026-05-17 12:00 |
17:32:46.59 |
+21:50:29.7 |
HIP 85873 |
2.86 |
| 2026-05-18 00:00 |
17:32:33.32 |
+21:51:11.5 |
HIP 85873 |
4.87 |
| 2026-05-18 12:00 |
17:32:20.00 |
+21:51:52.4 |
HIP 85873 |
7.71 |
| 2026-05-19 00:00 |
17:32:06.64 |
+21:52:32.4 |
HIP 85873 |
10.74 |
| 2026-05-19 12:00 |
17:31:53.23 |
+21:53:11.5 |
HIP 85873 |
13.84 |
| 2026-05-20 00:00 |
17:31:39.78 |
+21:53:49.8 |
HIP 85873 |
16.98 |
| 2026-05-20 12:00 |
17:31:26.29 |
+21:54:27.1 |
HIP 85655 |
17.46 |
| 2026-05-21 00:00 |
17:31:12.76 |
+21:55:03.6 |
HIP 85655 |
14.40 |
| 2026-05-21 12:00 |
17:30:59.19 |
+21:55:39.1 |
HIP 85655 |
11.41 |
| 2026-05-22 00:00 |
17:30:45.58 |
+21:56:13.8 |
HIP 85655 |
8.59 |
| 2026-05-22 12:00 |
17:30:31.93 |
+21:56:47.5 |
HIP 85655 |
6.16 |
| 2026-05-23 00:00 |
17:30:18.25 |
+21:57:20.3 |
HIP 85655 |
4.79 |
| 2026-05-23 12:00 |
17:30:04.52 |
+21:57:52.2 |
HIP 85655 |
5.37 |
| 2026-05-24 00:00 |
17:29:50.77 |
+21:58:23.2 |
HIP 85655 |
7.47 |
| 2026-05-24 12:00 |
17:29:36.98 |
+21:58:53.3 |
HIP 85655 |
10.19 |
| 2026-05-25 00:00 |
17:29:23.16 |
+21:59:22.4 |
HIP 85567 |
8.92 |
| 2026-05-25 12:00 |
17:29:09.31 |
+21:59:50.6 |
HIP 85567 |
8.16 |
| 2026-05-26 00:00 |
17:28:55.43 |
+22:00:17.9 |
HIP 85567 |
8.66 |
| 2026-05-26 12:00 |
17:28:41.52 |
+22:00:44.3 |
HIP 85567 |
10.24 |
| 2026-05-27 00:00 |
17:28:27.58 |
+22:01:09.7 |
HIP 85567 |
12.49 |
| 2026-05-27 12:00 |
17:28:13.61 |
+22:01:34.1 |
HIP 85567 |
15.13 |
| 2026-05-28 00:00 |
17:27:59.61 |
+22:01:57.6 |
HIP 85567 |
17.99 |
| 2026-05-28 12:00 |
17:27:45.59 |
+22:02:20.2 |
HIP 85344 |
19.54 |
| 2026-05-29 00:00 |
17:27:31.55 |
+22:02:41.8 |
HIP 85344 |
16.29 |
| 2026-05-29 12:00 |
17:27:17.48 |
+22:03:02.5 |
HIP 85344 |
13.05 |
| 2026-05-30 00:00 |
17:27:03.39 |
+22:03:22.2 |
HIP 85344 |
9.84 |
| 2026-05-30 12:00 |
17:26:49.28 |
+22:03:41.0 |
HIP 85344 |
6.69 |
| 2026-05-31 00:00 |
17:26:35.15 |
+22:03:58.8 |
HIP 85344 |
3.80 |
| 2026-05-31 12:00 |
17:26:21.00 |
+22:04:15.6 |
HIP 85344 |
2.39 |
| 2026-06-01 00:00 |
17:26:06.83 |
+22:04:31.5 |
HIP 85344 |
4.33 |
| 2026-06-01 12:00 |
17:25:52.64 |
+22:04:46.4 |
HIP 85344 |
7.32 |
| 2026-06-02 00:00 |
17:25:38.44 |
+22:05:00.3 |
HIP 85255 |
7.60 |