C/2021 B2 (PANSTARRS)
| Parameter |
Value |
| Designation |
C/2021 B2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-05-04T06:39:22.443840Z |
| Orbit solution date (soln_date, UTC) |
2022-06-07T21:45:07Z |
| Obs used |
93 |
| NEO |
- |
| M1 |
12.200 |
| K1 |
12.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-01-17T05:33:50.803200Z |
| Discovery magnitude (MPC) |
19.96 w |
| Discovery observatory (MPC) |
F51 · Pan-STARRS 1, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-04-03.0000000 |
| e |
0.99252519 |
| q (au) |
2.513062 |
| a (au) |
336.204150 |
| i (deg) |
38.094193 |
| Ω (om, deg) |
120.555561 |
| ω (w, deg) |
334.974070 |
| M (ma, deg) |
359.994999 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.993 + 5.531\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.993 |
| n |
5.531 |
| gf |
0.921 |
| gb |
-0.787 |
| k |
0.997 |
| δ90 |
6.451 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2020-12-24 |
2021-04-06 |
+21.0055 |
-9.074 |
| 2022-01-05 |
2022-05-25 |
-2.3834 |
+1.368 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
16:01:50.71 |
+16:26:39.6 |
HIP 78560 |
11.01 |
| 2026-02-03 12:00 |
16:01:54.66 |
+16:27:38.2 |
HIP 78560 |
10.96 |
| 2026-02-04 00:00 |
16:01:58.54 |
+16:28:37.3 |
HIP 78560 |
11.09 |
| 2026-02-04 12:00 |
16:02:02.35 |
+16:29:36.8 |
HIP 78560 |
11.40 |
| 2026-02-05 00:00 |
16:02:06.09 |
+16:30:36.6 |
HIP 78560 |
11.87 |
| 2026-02-05 12:00 |
16:02:09.76 |
+16:31:36.9 |
HIP 78560 |
12.48 |
| 2026-02-06 00:00 |
16:02:13.36 |
+16:32:37.6 |
HIP 78560 |
13.20 |
| 2026-02-06 12:00 |
16:02:16.88 |
+16:33:38.6 |
HIP 78560 |
14.02 |
| 2026-02-07 00:00 |
16:02:20.34 |
+16:34:40.1 |
HIP 78560 |
14.93 |
| 2026-02-07 12:00 |
16:02:23.72 |
+16:35:41.9 |
HIP 78560 |
15.89 |
| 2026-02-08 00:00 |
16:02:27.03 |
+16:36:44.1 |
HIP 78560 |
16.91 |
| 2026-02-08 12:00 |
16:02:30.27 |
+16:37:46.6 |
HIP 78560 |
17.98 |
| 2026-02-09 00:00 |
16:02:33.43 |
+16:38:49.6 |
HIP 78560 |
19.07 |
| 2026-02-09 12:00 |
16:02:36.52 |
+16:39:52.8 |
HIP 78560 |
20.20 |
| 2026-02-10 00:00 |
16:02:39.54 |
+16:40:56.5 |
HIP 78560 |
21.34 |
| 2026-02-10 12:00 |
16:02:42.49 |
+16:42:00.5 |
HIP 78560 |
22.51 |
| 2026-02-11 00:00 |
16:02:45.36 |
+16:43:04.8 |
HIP 78560 |
23.69 |
| 2026-02-11 12:00 |
16:02:48.15 |
+16:44:09.5 |
HIP 78560 |
24.88 |
| 2026-02-12 00:00 |
16:02:50.88 |
+16:45:14.5 |
HIP 78560 |
26.07 |
| 2026-02-12 12:00 |
16:02:53.52 |
+16:46:19.9 |
HIP 78719 |
27.20 |
| 2026-02-13 00:00 |
16:02:56.10 |
+16:47:25.6 |
HIP 78719 |
25.99 |
| 2026-02-13 12:00 |
16:02:58.60 |
+16:48:31.6 |
HIP 78719 |
24.78 |
| 2026-02-14 00:00 |
16:03:01.02 |
+16:49:37.9 |
HIP 78719 |
23.59 |
| 2026-02-14 12:00 |
16:03:03.37 |
+16:50:44.5 |
HIP 78719 |
22.42 |
| 2026-02-15 00:00 |
16:03:05.64 |
+16:51:51.4 |
HIP 78719 |
21.27 |
| 2026-02-15 12:00 |
16:03:07.84 |
+16:52:58.6 |
HIP 78719 |
20.13 |
| 2026-02-16 00:00 |
16:03:09.96 |
+16:54:06.1 |
HIP 78719 |
19.02 |
| 2026-02-16 12:00 |
16:03:12.00 |
+16:55:13.9 |
HIP 78719 |
17.94 |
| 2026-02-17 00:00 |
16:03:13.97 |
+16:56:22.0 |
HIP 78719 |
16.90 |
| 2026-02-17 12:00 |
16:03:15.86 |
+16:57:30.3 |
HIP 78719 |
15.89 |
| 2026-02-18 00:00 |
16:03:17.68 |
+16:58:38.9 |
HIP 78719 |
14.92 |
| 2026-02-18 12:00 |
16:03:19.42 |
+16:59:47.8 |
HIP 78719 |
14.02 |
| 2026-02-19 00:00 |
16:03:21.08 |
+17:00:56.9 |
HIP 78719 |
13.17 |
| 2026-02-19 12:00 |
16:03:22.66 |
+17:02:06.3 |
HIP 78719 |
12.41 |
| 2026-02-20 00:00 |
16:03:24.17 |
+17:03:15.9 |
HIP 78719 |
11.74 |
| 2026-02-20 12:00 |
16:03:25.60 |
+17:04:25.8 |
HIP 78719 |
11.19 |
| 2026-02-21 00:00 |
16:03:26.96 |
+17:05:35.9 |
HIP 78719 |
10.75 |
| 2026-02-21 12:00 |
16:03:28.24 |
+17:06:46.2 |
HIP 78719 |
10.47 |
| 2026-02-22 00:00 |
16:03:29.44 |
+17:07:56.7 |
HIP 78719 |
10.33 |
| 2026-02-22 12:00 |
16:03:30.56 |
+17:09:07.4 |
HIP 78719 |
10.35 |
| 2026-02-23 00:00 |
16:03:31.60 |
+17:10:18.3 |
HIP 78719 |
10.54 |
| 2026-02-23 12:00 |
16:03:32.57 |
+17:11:29.5 |
HIP 78719 |
10.87 |
| 2026-02-24 00:00 |
16:03:33.46 |
+17:12:40.8 |
HIP 78719 |
11.34 |