| Parameter |
Value |
| Designation |
C/2015 O1 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-02-19T00:42:22.034880Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:13Z |
| Obs used |
3677 |
| NEO |
- |
| M1 |
7.200 |
| K1 |
8.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-02-12.0000000 |
| e |
0.99999427 |
| q (au) |
3.729638 |
| a (au) |
651202.297761 |
| i (deg) |
127.211078 |
| Ω (om, deg) |
299.855849 |
| ω (w, deg) |
89.593861 |
| M (ma, deg) |
360.000000 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.999 + 2.835\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.999 |
| n |
2.835 |
| gf |
0.898 |
| gb |
-0.500 |
| k |
0.965 |
| δ90 |
1.020 |
| 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 |
| 2015-06-15 |
2017-06-06 |
-1.5915 |
+0.977 |
| 2017-06-06 |
2018-02-18 |
+13.0862 |
-8.231 |
| 2018-02-21 |
2020-03-20 |
+2.8414 |
-2.032 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
06:24:13.47 |
-06:37:21.8 |
HIP 30262 |
35.52 |
| 2026-09-20 12:00 |
06:24:13.61 |
-06:38:12.7 |
HIP 30262 |
35.82 |
| 2026-09-21 00:00 |
06:24:13.70 |
-06:39:03.6 |
HIP 30262 |
36.13 |
| 2026-09-21 12:00 |
06:24:13.75 |
-06:39:54.6 |
HIP 30262 |
36.44 |
| 2026-09-22 00:00 |
06:24:13.75 |
-06:40:45.6 |
HIP 30262 |
36.77 |
| 2026-09-22 12:00 |
06:24:13.69 |
-06:41:36.6 |
HIP 30262 |
37.09 |
| 2026-09-23 00:00 |
06:24:13.59 |
-06:42:27.7 |
HIP 30262 |
37.42 |
| 2026-09-23 12:00 |
06:24:13.44 |
-06:43:18.8 |
HIP 30262 |
37.76 |
| 2026-09-24 00:00 |
06:24:13.25 |
-06:44:10.0 |
HIP 30262 |
38.11 |
| 2026-09-24 12:00 |
06:24:13.00 |
-06:45:01.2 |
HIP 30262 |
38.46 |
| 2026-09-25 00:00 |
06:24:12.70 |
-06:45:52.4 |
HIP 30262 |
38.81 |
| 2026-09-25 12:00 |
06:24:12.35 |
-06:46:43.6 |
HIP 30262 |
39.17 |
| 2026-09-26 00:00 |
06:24:11.96 |
-06:47:34.9 |
HIP 30262 |
39.53 |
| 2026-09-26 12:00 |
06:24:11.51 |
-06:48:26.2 |
HIP 30262 |
39.90 |
| 2026-09-27 00:00 |
06:24:11.02 |
-06:49:17.4 |
HIP 30380 |
39.98 |
| 2026-09-27 12:00 |
06:24:10.47 |
-06:50:08.7 |
HIP 30380 |
39.13 |
| 2026-09-28 00:00 |
06:24:09.88 |
-06:51:00.0 |
HIP 30380 |
38.27 |
| 2026-09-28 12:00 |
06:24:09.24 |
-06:51:51.4 |
HIP 30380 |
37.41 |
| 2026-09-29 00:00 |
06:24:08.55 |
-06:52:42.7 |
HIP 30380 |
36.55 |
| 2026-09-29 12:00 |
06:24:07.80 |
-06:53:34.0 |
HIP 30380 |
35.68 |
| 2026-09-30 00:00 |
06:24:07.01 |
-06:54:25.3 |
HIP 30380 |
34.81 |
| 2026-09-30 12:00 |
06:24:06.17 |
-06:55:16.6 |
HIP 30380 |
33.94 |
| 2026-10-01 00:00 |
06:24:05.28 |
-06:56:07.9 |
HIP 30380 |
33.06 |
| 2026-10-01 12:00 |
06:24:04.33 |
-06:56:59.2 |
HIP 30380 |
32.18 |
| 2026-10-02 00:00 |
06:24:03.34 |
-06:57:50.5 |
HIP 30380 |
31.29 |
| 2026-10-02 12:00 |
06:24:02.30 |
-06:58:41.7 |
HIP 30380 |
30.40 |
| 2026-10-03 00:00 |
06:24:01.20 |
-06:59:32.9 |
HIP 30380 |
29.51 |
| 2026-10-03 12:00 |
06:24:00.06 |
-07:00:24.1 |
HIP 30380 |
28.61 |
| 2026-10-04 00:00 |
06:23:58.87 |
-07:01:15.3 |
HIP 30380 |
27.71 |
| 2026-10-04 12:00 |
06:23:57.62 |
-07:02:06.5 |
HIP 30380 |
26.80 |
| 2026-10-05 00:00 |
06:23:56.33 |
-07:02:57.6 |
HIP 30380 |
25.89 |
| 2026-10-05 12:00 |
06:23:54.98 |
-07:03:48.7 |
HIP 30380 |
24.97 |
| 2026-10-06 00:00 |
06:23:53.58 |
-07:04:39.7 |
HIP 30380 |
24.06 |
| 2026-10-06 12:00 |
06:23:52.14 |
-07:05:30.7 |
HIP 30380 |
23.13 |
| 2026-10-07 00:00 |
06:23:50.64 |
-07:06:21.6 |
HIP 30380 |
22.21 |
| 2026-10-07 12:00 |
06:23:49.09 |
-07:07:12.5 |
HIP 30380 |
21.28 |
| 2026-10-08 00:00 |
06:23:47.49 |
-07:08:03.3 |
HIP 30380 |
20.35 |
| 2026-10-08 12:00 |
06:23:45.84 |
-07:08:54.1 |
HIP 30380 |
19.41 |
| 2026-10-09 00:00 |
06:23:44.14 |
-07:09:44.8 |
HIP 30380 |
18.47 |
| 2026-10-09 12:00 |
06:23:42.39 |
-07:10:35.4 |
HIP 30380 |
17.53 |
| 2026-10-10 00:00 |
06:23:40.59 |
-07:11:26.0 |
HIP 30380 |
16.59 |
| 2026-10-10 12:00 |
06:23:38.74 |
-07:12:16.5 |
HIP 30380 |
15.64 |
| 2026-10-11 00:00 |
06:23:36.84 |
-07:13:06.9 |
HIP 30380 |
14.69 |