C/2021 O3 (PANSTARRS)
| Parameter |
Value |
| Designation |
C/2021 O3 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-04-21T00:59:54.507840Z |
| Orbit solution date (soln_date, UTC) |
2024-08-08T14:32:18Z |
| Obs used |
760 |
| NEO |
- |
| M1 |
13.600 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-07-26T11:32:37.104000Z |
| Discovery magnitude (MPC) |
19.87 i |
| Discovery observatory (MPC) |
F51 · Pan-STARRS 1, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-10-30.0000000 |
| e |
1.00015130 |
| q (au) |
0.287322 |
| a (au) |
-1899.062785 |
| i (deg) |
56.772789 |
| Ω (om, deg) |
189.027335 |
| ω (w, deg) |
299.983286 |
| M (ma, deg) |
-0.002061 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.384 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.384 |
| n |
2.000 |
| gf |
0.800 |
| gb |
-0.680 |
| k |
0.800 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2021-07-26 |
2021-09-18 |
+2.7400 |
-1.427 |
| 2021-09-18 |
2021-11-07 |
+8.8781 |
-4.666 |
| 2021-11-07 |
2021-12-08 |
+4.2020 |
-2.285 |
| 2021-12-08 |
2022-04-19 |
+4.8581 |
-2.406 |
| 2022-04-22 |
2022-07-12 |
-0.0579 |
+1.173 |
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 |
19:34:01.11 |
+30:35:10.3 |
HIP 96295 |
10.38 |
| 2026-02-03 12:00 |
19:34:10.70 |
+30:36:01.4 |
HIP 96295 |
8.98 |
| 2026-02-04 00:00 |
19:34:20.25 |
+30:36:53.3 |
HIP 96295 |
7.99 |
| 2026-02-04 12:00 |
19:34:29.78 |
+30:37:45.9 |
HIP 96295 |
7.55 |
| 2026-02-05 00:00 |
19:34:39.27 |
+30:38:39.2 |
HIP 96295 |
7.78 |
| 2026-02-05 12:00 |
19:34:48.72 |
+30:39:33.3 |
HIP 96295 |
8.60 |
| 2026-02-06 00:00 |
19:34:58.14 |
+30:40:28.0 |
HIP 96295 |
9.88 |
| 2026-02-06 12:00 |
19:35:07.52 |
+30:41:23.4 |
HIP 96295 |
11.46 |
| 2026-02-07 00:00 |
19:35:16.87 |
+30:42:19.5 |
HIP 96295 |
13.23 |
| 2026-02-07 12:00 |
19:35:26.18 |
+30:43:16.3 |
HIP 96295 |
15.12 |
| 2026-02-08 00:00 |
19:35:35.46 |
+30:44:13.8 |
HIP 96295 |
17.09 |
| 2026-02-08 12:00 |
19:35:44.69 |
+30:45:12.0 |
HIP 96295 |
19.12 |
| 2026-02-09 00:00 |
19:35:53.89 |
+30:46:10.9 |
HIP 96295 |
21.19 |
| 2026-02-09 12:00 |
19:36:03.05 |
+30:47:10.4 |
HIP 96295 |
23.29 |
| 2026-02-10 00:00 |
19:36:12.17 |
+30:48:10.7 |
HIP 96295 |
25.40 |
| 2026-02-10 12:00 |
19:36:21.25 |
+30:49:11.6 |
HIP 96452 |
25.13 |
| 2026-02-11 00:00 |
19:36:30.29 |
+30:50:13.1 |
HIP 96452 |
23.96 |
| 2026-02-11 12:00 |
19:36:39.29 |
+30:51:15.4 |
HIP 96452 |
22.93 |
| 2026-02-12 00:00 |
19:36:48.25 |
+30:52:18.3 |
HIP 96452 |
22.05 |
| 2026-02-12 12:00 |
19:36:57.17 |
+30:53:21.8 |
HIP 96452 |
21.36 |
| 2026-02-13 00:00 |
19:37:06.04 |
+30:54:26.0 |
HIP 96452 |
20.85 |
| 2026-02-13 12:00 |
19:37:14.87 |
+30:55:30.9 |
HIP 96452 |
20.55 |
| 2026-02-14 00:00 |
19:37:23.66 |
+30:56:36.4 |
HIP 96452 |
20.47 |
| 2026-02-14 12:00 |
19:37:32.40 |
+30:57:42.5 |
HIP 96452 |
20.60 |
| 2026-02-15 00:00 |
19:37:41.10 |
+30:58:49.3 |
HIP 96618 |
18.91 |
| 2026-02-15 12:00 |
19:37:49.75 |
+30:59:56.7 |
HIP 96618 |
16.86 |
| 2026-02-16 00:00 |
19:37:58.35 |
+31:01:04.8 |
HIP 96618 |
14.85 |
| 2026-02-16 12:00 |
19:38:06.91 |
+31:02:13.5 |
HIP 96618 |
12.88 |
| 2026-02-17 00:00 |
19:38:15.43 |
+31:03:22.7 |
HIP 96618 |
10.97 |
| 2026-02-17 12:00 |
19:38:23.89 |
+31:04:32.7 |
HIP 96618 |
9.18 |
| 2026-02-18 00:00 |
19:38:32.31 |
+31:05:43.2 |
HIP 96618 |
7.56 |
| 2026-02-18 12:00 |
19:38:40.68 |
+31:06:54.3 |
HIP 96618 |
6.26 |
| 2026-02-19 00:00 |
19:38:48.99 |
+31:08:06.0 |
HIP 96618 |
5.51 |
| 2026-02-19 12:00 |
19:38:57.26 |
+31:09:18.3 |
HIP 96618 |
5.52 |
| 2026-02-20 00:00 |
19:39:05.48 |
+31:10:31.2 |
HIP 96618 |
6.30 |
| 2026-02-20 12:00 |
19:39:13.65 |
+31:11:44.7 |
HIP 96618 |
7.60 |
| 2026-02-21 00:00 |
19:39:21.77 |
+31:12:58.8 |
HIP 96618 |
9.20 |
| 2026-02-21 12:00 |
19:39:29.83 |
+31:14:13.5 |
HIP 96618 |
10.98 |
| 2026-02-22 00:00 |
19:39:37.84 |
+31:15:28.7 |
HIP 96618 |
12.85 |
| 2026-02-22 12:00 |
19:39:45.80 |
+31:16:44.5 |
HIP 96804 |
14.06 |
| 2026-02-23 00:00 |
19:39:53.71 |
+31:18:00.8 |
HIP 96804 |
11.95 |
| 2026-02-23 12:00 |
19:40:01.56 |
+31:19:17.7 |
HIP 96804 |
9.85 |
| 2026-02-24 00:00 |
19:40:09.36 |
+31:20:35.1 |
HIP 96804 |
7.76 |