| 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) |
| 2026-03-26 00:00 |
06:04:47.44 |
-05:47:17.5 |
HIP 28897 |
19.40 |
| 2026-03-26 12:00 |
06:04:47.27 |
-05:46:42.2 |
HIP 28897 |
19.62 |
| 2026-03-27 00:00 |
06:04:47.14 |
-05:46:07.0 |
HIP 28897 |
19.84 |
| 2026-03-27 12:00 |
06:04:47.07 |
-05:45:31.9 |
HIP 28897 |
20.06 |
| 2026-03-28 00:00 |
06:04:47.06 |
-05:44:56.9 |
HIP 28897 |
20.29 |
| 2026-03-28 12:00 |
06:04:47.09 |
-05:44:21.9 |
HIP 28897 |
20.51 |
| 2026-03-29 00:00 |
06:04:47.17 |
-05:43:47.1 |
HIP 28897 |
20.74 |
| 2026-03-29 12:00 |
06:04:47.31 |
-05:43:12.3 |
HIP 28897 |
20.97 |
| 2026-03-30 00:00 |
06:04:47.50 |
-05:42:37.6 |
HIP 28897 |
21.20 |
| 2026-03-30 12:00 |
06:04:47.73 |
-05:42:03.0 |
HIP 28897 |
21.43 |
| 2026-03-31 00:00 |
06:04:48.02 |
-05:41:28.5 |
HIP 28809 |
20.99 |
| 2026-03-31 12:00 |
06:04:48.36 |
-05:40:54.1 |
HIP 28809 |
20.41 |
| 2026-04-01 00:00 |
06:04:48.75 |
-05:40:19.8 |
HIP 28809 |
19.84 |
| 2026-04-01 12:00 |
06:04:49.19 |
-05:39:45.7 |
HIP 28809 |
19.26 |
| 2026-04-02 00:00 |
06:04:49.68 |
-05:39:11.6 |
HIP 28809 |
18.68 |
| 2026-04-02 12:00 |
06:04:50.22 |
-05:38:37.6 |
HIP 28809 |
18.11 |
| 2026-04-03 00:00 |
06:04:50.81 |
-05:38:03.7 |
HIP 28809 |
17.53 |
| 2026-04-03 12:00 |
06:04:51.45 |
-05:37:30.0 |
HIP 28809 |
16.96 |
| 2026-04-04 00:00 |
06:04:52.14 |
-05:36:56.4 |
HIP 28809 |
16.39 |
| 2026-04-04 12:00 |
06:04:52.88 |
-05:36:22.8 |
HIP 28809 |
15.82 |
| 2026-04-05 00:00 |
06:04:53.67 |
-05:35:49.5 |
HIP 28809 |
15.26 |
| 2026-04-05 12:00 |
06:04:54.50 |
-05:35:16.2 |
HIP 28809 |
14.69 |
| 2026-04-06 00:00 |
06:04:55.39 |
-05:34:43.1 |
HIP 28809 |
14.14 |
| 2026-04-06 12:00 |
06:04:56.32 |
-05:34:10.1 |
HIP 28809 |
13.59 |
| 2026-04-07 00:00 |
06:04:57.30 |
-05:33:37.2 |
HIP 28809 |
13.04 |
| 2026-04-07 12:00 |
06:04:58.33 |
-05:33:04.5 |
HIP 28809 |
12.50 |
| 2026-04-08 00:00 |
06:04:59.41 |
-05:32:31.9 |
HIP 28809 |
11.98 |
| 2026-04-08 12:00 |
06:05:00.54 |
-05:31:59.4 |
HIP 28809 |
11.46 |
| 2026-04-09 00:00 |
06:05:01.71 |
-05:31:27.1 |
HIP 28809 |
10.95 |
| 2026-04-09 12:00 |
06:05:02.94 |
-05:30:54.9 |
HIP 28809 |
10.47 |
| 2026-04-10 00:00 |
06:05:04.21 |
-05:30:22.9 |
HIP 28809 |
10.00 |
| 2026-04-10 12:00 |
06:05:05.52 |
-05:29:51.0 |
HIP 28809 |
9.55 |
| 2026-04-11 00:00 |
06:05:06.89 |
-05:29:19.3 |
HIP 28809 |
9.13 |
| 2026-04-11 12:00 |
06:05:08.30 |
-05:28:47.8 |
HIP 28809 |
8.75 |
| 2026-04-12 00:00 |
06:05:09.75 |
-05:28:16.4 |
HIP 28809 |
8.39 |
| 2026-04-12 12:00 |
06:05:11.25 |
-05:27:45.2 |
HIP 28809 |
8.09 |
| 2026-04-13 00:00 |
06:05:12.80 |
-05:27:14.1 |
HIP 28809 |
7.83 |
| 2026-04-13 12:00 |
06:05:14.40 |
-05:26:43.2 |
HIP 28809 |
7.62 |
| 2026-04-14 00:00 |
06:05:16.04 |
-05:26:12.5 |
HIP 28809 |
7.48 |
| 2026-04-14 12:00 |
06:05:17.73 |
-05:25:41.9 |
HIP 28809 |
7.40 |
| 2026-04-15 00:00 |
06:05:19.46 |
-05:25:11.6 |
HIP 28809 |
7.39 |
| 2026-04-15 12:00 |
06:05:21.23 |
-05:24:41.4 |
HIP 28809 |
7.46 |
| 2026-04-16 00:00 |
06:05:23.06 |
-05:24:11.3 |
HIP 28809 |
7.59 |