| Parameter |
Value |
| Designation |
C/2013 W2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2015-01-05T06:10:39.014400Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:43Z |
| Obs used |
179 |
| NEO |
- |
| M1 |
6.900 |
| K1 |
13.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-01-20.0000000 |
| e |
0.57470690 |
| q (au) |
4.444439 |
| a (au) |
10.450297 |
| i (deg) |
4.567063 |
| Ω (om, deg) |
179.842795 |
| ω (w, deg) |
307.197933 |
| M (ma, deg) |
0.430116 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.108 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.108 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.734 |
| k |
1.000 |
| 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 |
| 2013-11-27 |
2014-10-24 |
+27.9138 |
-19.052 |
| 2015-01-17 |
2016-05-05 |
+3.0612 |
-2.167 |
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 |
19:26:46.37 |
-17:07:26.7 |
HIP 95610 |
20.44 |
| 2026-05-12 12:00 |
19:26:43.51 |
-17:07:24.3 |
HIP 95610 |
20.41 |
| 2026-05-13 00:00 |
19:26:40.58 |
-17:07:22.0 |
HIP 95610 |
20.40 |
| 2026-05-13 12:00 |
19:26:37.59 |
-17:07:20.0 |
HIP 95610 |
20.43 |
| 2026-05-14 00:00 |
19:26:34.52 |
-17:07:18.1 |
HIP 95610 |
20.48 |
| 2026-05-14 12:00 |
19:26:31.39 |
-17:07:16.4 |
HIP 95610 |
20.57 |
| 2026-05-15 00:00 |
19:26:28.20 |
-17:07:14.9 |
HIP 95610 |
20.69 |
| 2026-05-15 12:00 |
19:26:24.93 |
-17:07:13.5 |
HIP 95610 |
20.85 |
| 2026-05-16 00:00 |
19:26:21.61 |
-17:07:12.4 |
HIP 95610 |
21.04 |
| 2026-05-16 12:00 |
19:26:18.21 |
-17:07:11.4 |
HIP 95610 |
21.26 |
| 2026-05-17 00:00 |
19:26:14.75 |
-17:07:10.6 |
HIP 95610 |
21.52 |
| 2026-05-17 12:00 |
19:26:11.23 |
-17:07:10.0 |
HIP 95482 |
21.08 |
| 2026-05-18 00:00 |
19:26:07.64 |
-17:07:09.6 |
HIP 95482 |
20.58 |
| 2026-05-18 12:00 |
19:26:03.99 |
-17:07:09.3 |
HIP 95482 |
20.10 |
| 2026-05-19 00:00 |
19:26:00.28 |
-17:07:09.2 |
HIP 95482 |
19.63 |
| 2026-05-19 12:00 |
19:25:56.50 |
-17:07:09.3 |
HIP 95482 |
19.20 |
| 2026-05-20 00:00 |
19:25:52.66 |
-17:07:09.6 |
HIP 95482 |
18.79 |
| 2026-05-20 12:00 |
19:25:48.76 |
-17:07:10.1 |
HIP 95482 |
18.41 |
| 2026-05-21 00:00 |
19:25:44.80 |
-17:07:10.7 |
HIP 95482 |
18.08 |
| 2026-05-21 12:00 |
19:25:40.77 |
-17:07:11.5 |
HIP 95482 |
17.79 |
| 2026-05-22 00:00 |
19:25:36.68 |
-17:07:12.5 |
HIP 95482 |
17.54 |
| 2026-05-22 12:00 |
19:25:32.54 |
-17:07:13.7 |
HIP 95482 |
17.35 |
| 2026-05-23 00:00 |
19:25:28.33 |
-17:07:15.0 |
HIP 95482 |
17.21 |
| 2026-05-23 12:00 |
19:25:24.06 |
-17:07:16.5 |
HIP 95482 |
17.13 |
| 2026-05-24 00:00 |
19:25:19.74 |
-17:07:18.2 |
HIP 95482 |
17.12 |
| 2026-05-24 12:00 |
19:25:15.35 |
-17:07:20.1 |
HIP 95482 |
17.17 |
| 2026-05-25 00:00 |
19:25:10.91 |
-17:07:22.1 |
HIP 95482 |
17.29 |
| 2026-05-25 12:00 |
19:25:06.41 |
-17:07:24.3 |
HIP 95482 |
17.48 |
| 2026-05-26 00:00 |
19:25:01.85 |
-17:07:26.7 |
HIP 95482 |
17.74 |
| 2026-05-26 12:00 |
19:24:57.23 |
-17:07:29.3 |
HIP 95343 |
16.86 |
| 2026-05-27 00:00 |
19:24:52.56 |
-17:07:32.0 |
HIP 95343 |
15.77 |
| 2026-05-27 12:00 |
19:24:47.83 |
-17:07:34.9 |
HIP 95343 |
14.67 |
| 2026-05-28 00:00 |
19:24:43.05 |
-17:07:38.0 |
HIP 95343 |
13.56 |
| 2026-05-28 12:00 |
19:24:38.21 |
-17:07:41.2 |
HIP 95343 |
12.45 |
| 2026-05-29 00:00 |
19:24:33.32 |
-17:07:44.6 |
HIP 95343 |
11.33 |
| 2026-05-29 12:00 |
19:24:28.37 |
-17:07:48.2 |
HIP 95343 |
10.21 |
| 2026-05-30 00:00 |
19:24:23.36 |
-17:07:51.9 |
HIP 95343 |
9.09 |
| 2026-05-30 12:00 |
19:24:18.31 |
-17:07:55.8 |
HIP 95343 |
7.99 |
| 2026-05-31 00:00 |
19:24:13.20 |
-17:08:00.0 |
HIP 95343 |
6.90 |
| 2026-05-31 12:00 |
19:24:08.04 |
-17:08:04.2 |
HIP 95343 |
5.86 |
| 2026-06-01 00:00 |
19:24:02.82 |
-17:08:08.6 |
HIP 95343 |
4.90 |
| 2026-06-01 12:00 |
19:23:57.56 |
-17:08:13.1 |
HIP 95343 |
4.08 |
| 2026-06-02 00:00 |
19:23:52.24 |
-17:08:17.9 |
HIP 95343 |
3.54 |