| 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 |
-0.507 |
| 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) |
| 2026-07-29 00:00 |
19:10:49.47 |
-17:31:00.5 |
HIP 94061 |
26.86 |
| 2026-07-29 12:00 |
19:10:42.64 |
-17:31:16.8 |
HIP 94061 |
25.23 |
| 2026-07-30 00:00 |
19:10:35.84 |
-17:31:33.2 |
HIP 94061 |
23.60 |
| 2026-07-30 12:00 |
19:10:29.06 |
-17:31:49.5 |
HIP 94061 |
21.98 |
| 2026-07-31 00:00 |
19:10:22.32 |
-17:32:05.9 |
HIP 94061 |
20.37 |
| 2026-07-31 12:00 |
19:10:15.61 |
-17:32:22.3 |
HIP 94061 |
18.77 |
| 2026-08-01 00:00 |
19:10:08.93 |
-17:32:38.7 |
HIP 94061 |
17.18 |
| 2026-08-01 12:00 |
19:10:02.28 |
-17:32:55.1 |
HIP 94061 |
15.61 |
| 2026-08-02 00:00 |
19:09:55.66 |
-17:33:11.5 |
HIP 94061 |
14.05 |
| 2026-08-02 12:00 |
19:09:49.08 |
-17:33:28.0 |
HIP 94061 |
12.51 |
| 2026-08-03 00:00 |
19:09:42.53 |
-17:33:44.4 |
HIP 94061 |
11.00 |
| 2026-08-03 12:00 |
19:09:36.01 |
-17:34:00.9 |
HIP 94061 |
9.52 |
| 2026-08-04 00:00 |
19:09:29.53 |
-17:34:17.4 |
HIP 94061 |
8.08 |
| 2026-08-04 12:00 |
19:09:23.09 |
-17:34:33.8 |
HIP 94061 |
6.70 |
| 2026-08-05 00:00 |
19:09:16.68 |
-17:34:50.3 |
HIP 94061 |
5.44 |
| 2026-08-05 12:00 |
19:09:10.31 |
-17:35:06.8 |
HIP 94061 |
4.38 |
| 2026-08-06 00:00 |
19:09:03.98 |
-17:35:23.3 |
HIP 94061 |
3.67 |
| 2026-08-06 12:00 |
19:08:57.68 |
-17:35:39.8 |
HIP 94061 |
3.54 |
| 2026-08-07 00:00 |
19:08:51.42 |
-17:35:56.3 |
HIP 94061 |
4.03 |
| 2026-08-07 12:00 |
19:08:45.21 |
-17:36:12.8 |
HIP 94061 |
4.94 |
| 2026-08-08 00:00 |
19:08:39.03 |
-17:36:29.4 |
HIP 94061 |
6.09 |
| 2026-08-08 12:00 |
19:08:32.90 |
-17:36:45.9 |
HIP 94061 |
7.36 |
| 2026-08-09 00:00 |
19:08:26.80 |
-17:37:02.4 |
HIP 94061 |
8.69 |
| 2026-08-09 12:00 |
19:08:20.75 |
-17:37:18.8 |
HIP 94061 |
10.05 |
| 2026-08-10 00:00 |
19:08:14.74 |
-17:37:35.3 |
HIP 94061 |
11.43 |
| 2026-08-10 12:00 |
19:08:08.78 |
-17:37:51.8 |
HIP 94061 |
12.82 |
| 2026-08-11 00:00 |
19:08:02.86 |
-17:38:08.3 |
HIP 94061 |
14.21 |
| 2026-08-11 12:00 |
19:07:56.98 |
-17:38:24.7 |
HIP 94061 |
15.60 |
| 2026-08-12 00:00 |
19:07:51.15 |
-17:38:41.2 |
HIP 94061 |
16.98 |
| 2026-08-12 12:00 |
19:07:45.37 |
-17:38:57.6 |
HIP 94061 |
18.36 |
| 2026-08-13 00:00 |
19:07:39.63 |
-17:39:14.0 |
HIP 94061 |
19.73 |
| 2026-08-13 12:00 |
19:07:33.94 |
-17:39:30.4 |
HIP 94061 |
21.10 |
| 2026-08-14 00:00 |
19:07:28.30 |
-17:39:46.8 |
HIP 94061 |
22.45 |
| 2026-08-14 12:00 |
19:07:22.71 |
-17:40:03.1 |
HIP 94061 |
23.80 |
| 2026-08-15 00:00 |
19:07:17.16 |
-17:40:19.5 |
HIP 94061 |
25.14 |
| 2026-08-15 12:00 |
19:07:11.67 |
-17:40:35.8 |
HIP 93906 |
26.14 |
| 2026-08-16 00:00 |
19:07:06.22 |
-17:40:52.1 |
HIP 93906 |
26.52 |
| 2026-08-16 12:00 |
19:07:00.83 |
-17:41:08.3 |
HIP 93906 |
26.96 |
| 2026-08-17 00:00 |
19:06:55.49 |
-17:41:24.6 |
HIP 93906 |
27.45 |
| 2026-08-17 12:00 |
19:06:50.20 |
-17:41:40.8 |
HIP 93906 |
28.00 |
| 2026-08-18 00:00 |
19:06:44.96 |
-17:41:57.0 |
HIP 93906 |
28.58 |
| 2026-08-18 12:00 |
19:06:39.78 |
-17:42:13.1 |
HIP 93693 |
27.59 |
| 2026-08-19 00:00 |
19:06:34.64 |
-17:42:29.2 |
HIP 93693 |
26.34 |