| 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
$$
M_a = (7.985 + 2.835\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.985 |
| n |
2.835 |
| gf |
0.895 |
| gb |
-0.500 |
| k |
0.966 |
| δ90 |
1.089 |
| 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 |
-1.5918 |
+0.977 |
| 2017-06-06 |
2018-02-18 |
+13.0867 |
-8.232 |
| 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) |
| 2026-05-12 00:00 |
06:07:52.39 |
-05:03:14.5 |
HIP 29120 |
19.10 |
| 2026-05-12 12:00 |
06:07:56.17 |
-05:02:57.0 |
HIP 29120 |
18.97 |
| 2026-05-13 00:00 |
06:07:59.99 |
-05:02:39.8 |
HIP 29120 |
18.88 |
| 2026-05-13 12:00 |
06:08:03.83 |
-05:02:22.9 |
HIP 29120 |
18.84 |
| 2026-05-14 00:00 |
06:08:07.69 |
-05:02:06.3 |
HIP 29120 |
18.85 |
| 2026-05-14 12:00 |
06:08:11.59 |
-05:01:49.9 |
HIP 29120 |
18.90 |
| 2026-05-15 00:00 |
06:08:15.52 |
-05:01:33.8 |
HIP 29120 |
19.00 |
| 2026-05-15 12:00 |
06:08:19.47 |
-05:01:18.1 |
HIP 29201 |
18.67 |
| 2026-05-16 00:00 |
06:08:23.45 |
-05:01:02.6 |
HIP 29201 |
17.73 |
| 2026-05-16 12:00 |
06:08:27.45 |
-05:00:47.4 |
HIP 29201 |
16.79 |
| 2026-05-17 00:00 |
06:08:31.49 |
-05:00:32.5 |
HIP 29201 |
15.86 |
| 2026-05-17 12:00 |
06:08:35.55 |
-05:00:17.9 |
HIP 29201 |
14.93 |
| 2026-05-18 00:00 |
06:08:39.63 |
-05:00:03.6 |
HIP 29201 |
14.02 |
| 2026-05-18 12:00 |
06:08:43.74 |
-04:59:49.6 |
HIP 29201 |
13.11 |
| 2026-05-19 00:00 |
06:08:47.87 |
-04:59:35.9 |
HIP 29201 |
12.22 |
| 2026-05-19 12:00 |
06:08:52.03 |
-04:59:22.4 |
HIP 29201 |
11.35 |
| 2026-05-20 00:00 |
06:08:56.21 |
-04:59:09.3 |
HIP 29201 |
10.50 |
| 2026-05-20 12:00 |
06:09:00.42 |
-04:58:56.5 |
HIP 29201 |
9.70 |
| 2026-05-21 00:00 |
06:09:04.65 |
-04:58:44.0 |
HIP 29201 |
8.94 |
| 2026-05-21 12:00 |
06:09:08.90 |
-04:58:31.8 |
HIP 29201 |
8.24 |
| 2026-05-22 00:00 |
06:09:13.18 |
-04:58:19.9 |
HIP 29201 |
7.62 |
| 2026-05-22 12:00 |
06:09:17.48 |
-04:58:08.3 |
HIP 29201 |
7.11 |
| 2026-05-23 00:00 |
06:09:21.80 |
-04:57:57.0 |
HIP 29201 |
6.73 |
| 2026-05-23 12:00 |
06:09:26.14 |
-04:57:46.0 |
HIP 29201 |
6.51 |
| 2026-05-24 00:00 |
06:09:30.50 |
-04:57:35.4 |
HIP 29201 |
6.46 |
| 2026-05-24 12:00 |
06:09:34.89 |
-04:57:25.0 |
HIP 29201 |
6.60 |
| 2026-05-25 00:00 |
06:09:39.29 |
-04:57:14.9 |
HIP 29201 |
6.90 |
| 2026-05-25 12:00 |
06:09:43.72 |
-04:57:05.2 |
HIP 29201 |
7.36 |
| 2026-05-26 00:00 |
06:09:48.16 |
-04:56:55.7 |
HIP 29201 |
7.95 |
| 2026-05-26 12:00 |
06:09:52.63 |
-04:56:46.6 |
HIP 29201 |
8.64 |
| 2026-05-27 00:00 |
06:09:57.11 |
-04:56:37.8 |
HIP 29201 |
9.41 |
| 2026-05-27 12:00 |
06:10:01.61 |
-04:56:29.3 |
HIP 29201 |
10.25 |
| 2026-05-28 00:00 |
06:10:06.13 |
-04:56:21.1 |
HIP 29201 |
11.14 |
| 2026-05-28 12:00 |
06:10:10.67 |
-04:56:13.2 |
HIP 29201 |
12.07 |
| 2026-05-29 00:00 |
06:10:15.23 |
-04:56:05.6 |
HIP 29201 |
13.03 |
| 2026-05-29 12:00 |
06:10:19.80 |
-04:55:58.4 |
HIP 29201 |
14.03 |
| 2026-05-30 00:00 |
06:10:24.39 |
-04:55:51.4 |
HIP 29201 |
15.04 |
| 2026-05-30 12:00 |
06:10:29.00 |
-04:55:44.8 |
HIP 29358 |
14.58 |
| 2026-05-31 00:00 |
06:10:33.63 |
-04:55:38.5 |
HIP 29358 |
13.69 |
| 2026-05-31 12:00 |
06:10:38.27 |
-04:55:32.5 |
HIP 29358 |
12.84 |
| 2026-06-01 00:00 |
06:10:42.92 |
-04:55:26.8 |
HIP 29358 |
12.04 |
| 2026-06-01 12:00 |
06:10:47.60 |
-04:55:21.4 |
HIP 29358 |
11.29 |
| 2026-06-02 00:00 |
06:10:52.28 |
-04:55:16.4 |
HIP 29358 |
10.61 |