| Parameter |
Value |
| Designation |
C/2015 X5 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-12-31T00:50:40.139520Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:20Z |
| Obs used |
227 |
| NEO |
- |
| M1 |
6.600 |
| K1 |
10.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-07-11.0000000 |
| e |
1.00304318 |
| q (au) |
6.801746 |
| a (au) |
-2235.080422 |
| i (deg) |
124.284533 |
| Ω (om, deg) |
122.311473 |
| ω (w, deg) |
27.750506 |
| M (ma, deg) |
-0.001614 |
Magnitude
Scatter + Global Linear
$$
M_a = (6.073 + 3.992\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
6.073 |
| n |
3.992 |
| gf |
0.967 |
| gb |
-0.501 |
| k |
1.000 |
| δ90 |
9.960 |
| 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 |
| 2015-12-06 |
2017-12-23 |
+1.9144 |
-1.449 |
| 2018-01-05 |
2020-02-14 |
-8.6346 |
+7.072 |
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 |
21:37:59.50 |
+24:42:12.0 |
HIP 106873 |
21.12 |
| 2026-05-12 12:00 |
21:37:59.06 |
+24:42:53.6 |
HIP 106873 |
21.77 |
| 2026-05-13 00:00 |
21:37:58.57 |
+24:43:35.1 |
HIP 106873 |
22.43 |
| 2026-05-13 12:00 |
21:37:58.03 |
+24:44:16.4 |
HIP 106873 |
23.09 |
| 2026-05-14 00:00 |
21:37:57.43 |
+24:44:57.5 |
HIP 106873 |
23.76 |
| 2026-05-14 12:00 |
21:37:56.77 |
+24:45:38.4 |
HIP 106873 |
24.44 |
| 2026-05-15 00:00 |
21:37:56.06 |
+24:46:19.2 |
HIP 106873 |
25.11 |
| 2026-05-15 12:00 |
21:37:55.29 |
+24:46:59.7 |
HIP 106873 |
25.80 |
| 2026-05-16 00:00 |
21:37:54.47 |
+24:47:40.1 |
HIP 106873 |
26.48 |
| 2026-05-16 12:00 |
21:37:53.59 |
+24:48:20.2 |
HIP 106873 |
27.17 |
| 2026-05-17 00:00 |
21:37:52.66 |
+24:49:00.1 |
HIP 106873 |
27.86 |
| 2026-05-17 12:00 |
21:37:51.66 |
+24:49:39.8 |
HIP 106873 |
28.56 |
| 2026-05-18 00:00 |
21:37:50.62 |
+24:50:19.3 |
HIP 106873 |
29.25 |
| 2026-05-18 12:00 |
21:37:49.52 |
+24:50:58.6 |
HIP 106873 |
29.95 |
| 2026-05-19 00:00 |
21:37:48.36 |
+24:51:37.7 |
HIP 106746 |
29.66 |
| 2026-05-19 12:00 |
21:37:47.14 |
+24:52:16.5 |
HIP 106746 |
28.97 |
| 2026-05-20 00:00 |
21:37:45.87 |
+24:52:55.1 |
HIP 106746 |
28.29 |
| 2026-05-20 12:00 |
21:37:44.55 |
+24:53:33.4 |
HIP 106746 |
27.61 |
| 2026-05-21 00:00 |
21:37:43.17 |
+24:54:11.5 |
HIP 106746 |
26.93 |
| 2026-05-21 12:00 |
21:37:41.73 |
+24:54:49.3 |
HIP 106746 |
26.26 |
| 2026-05-22 00:00 |
21:37:40.24 |
+24:55:26.9 |
HIP 106746 |
25.59 |
| 2026-05-22 12:00 |
21:37:38.69 |
+24:56:04.3 |
HIP 106746 |
24.93 |
| 2026-05-23 00:00 |
21:37:37.08 |
+24:56:41.4 |
HIP 106746 |
24.27 |
| 2026-05-23 12:00 |
21:37:35.43 |
+24:57:18.2 |
HIP 106746 |
23.62 |
| 2026-05-24 00:00 |
21:37:33.71 |
+24:57:54.7 |
HIP 106746 |
22.98 |
| 2026-05-24 12:00 |
21:37:31.94 |
+24:58:31.0 |
HIP 106746 |
22.34 |
| 2026-05-25 00:00 |
21:37:30.12 |
+24:59:07.0 |
HIP 106746 |
21.72 |
| 2026-05-25 12:00 |
21:37:28.24 |
+24:59:42.7 |
HIP 106746 |
21.11 |
| 2026-05-26 00:00 |
21:37:26.30 |
+25:00:18.1 |
HIP 106746 |
20.50 |
| 2026-05-26 12:00 |
21:37:24.31 |
+25:00:53.3 |
HIP 106746 |
19.92 |
| 2026-05-27 00:00 |
21:37:22.27 |
+25:01:28.1 |
HIP 106746 |
19.34 |
| 2026-05-27 12:00 |
21:37:20.17 |
+25:02:02.7 |
HIP 106746 |
18.79 |
| 2026-05-28 00:00 |
21:37:18.02 |
+25:02:37.0 |
HIP 106746 |
18.25 |
| 2026-05-28 12:00 |
21:37:15.81 |
+25:03:10.9 |
HIP 106746 |
17.74 |
| 2026-05-29 00:00 |
21:37:13.55 |
+25:03:44.6 |
HIP 106746 |
17.25 |
| 2026-05-29 12:00 |
21:37:11.23 |
+25:04:18.0 |
HIP 106746 |
16.79 |
| 2026-05-30 00:00 |
21:37:08.86 |
+25:04:51.0 |
HIP 106746 |
16.36 |
| 2026-05-30 12:00 |
21:37:06.43 |
+25:05:23.7 |
HIP 106746 |
15.96 |
| 2026-05-31 00:00 |
21:37:03.95 |
+25:05:56.1 |
HIP 106746 |
15.60 |
| 2026-05-31 12:00 |
21:37:01.42 |
+25:06:28.2 |
HIP 106746 |
15.28 |
| 2026-06-01 00:00 |
21:36:58.83 |
+25:07:00.0 |
HIP 106746 |
15.00 |
| 2026-06-01 12:00 |
21:36:56.19 |
+25:07:31.4 |
HIP 106746 |
14.78 |
| 2026-06-02 00:00 |
21:36:53.49 |
+25:08:02.5 |
HIP 106746 |
14.60 |