| 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) |
| 2026-03-26 00:00 |
21:34:52.07 |
+23:34:03.3 |
HIP 106611 |
26.42 |
| 2026-03-26 12:00 |
21:34:56.15 |
+23:34:42.6 |
HIP 106611 |
25.48 |
| 2026-03-27 00:00 |
21:35:00.20 |
+23:35:22.2 |
HIP 106611 |
24.55 |
| 2026-03-27 12:00 |
21:35:04.21 |
+23:36:02.0 |
HIP 106611 |
23.64 |
| 2026-03-28 00:00 |
21:35:08.18 |
+23:36:41.9 |
HIP 106611 |
22.75 |
| 2026-03-28 12:00 |
21:35:12.12 |
+23:37:22.1 |
HIP 106611 |
21.88 |
| 2026-03-29 00:00 |
21:35:16.01 |
+23:38:02.5 |
HIP 106611 |
21.03 |
| 2026-03-29 12:00 |
21:35:19.87 |
+23:38:43.0 |
HIP 106611 |
20.21 |
| 2026-03-30 00:00 |
21:35:23.69 |
+23:39:23.8 |
HIP 106611 |
19.41 |
| 2026-03-30 12:00 |
21:35:27.47 |
+23:40:04.7 |
HIP 106611 |
18.64 |
| 2026-03-31 00:00 |
21:35:31.20 |
+23:40:45.8 |
HIP 106630 |
17.80 |
| 2026-03-31 12:00 |
21:35:34.90 |
+23:41:27.0 |
HIP 106630 |
16.92 |
| 2026-04-01 00:00 |
21:35:38.56 |
+23:42:08.5 |
HIP 106630 |
16.06 |
| 2026-04-01 12:00 |
21:35:42.18 |
+23:42:50.1 |
HIP 106630 |
15.24 |
| 2026-04-02 00:00 |
21:35:45.76 |
+23:43:31.8 |
HIP 106630 |
14.44 |
| 2026-04-02 12:00 |
21:35:49.30 |
+23:44:13.8 |
HIP 106630 |
13.68 |
| 2026-04-03 00:00 |
21:35:52.80 |
+23:44:55.9 |
HIP 106630 |
12.96 |
| 2026-04-03 12:00 |
21:35:56.25 |
+23:45:38.1 |
HIP 106630 |
12.28 |
| 2026-04-04 00:00 |
21:35:59.67 |
+23:46:20.5 |
HIP 106630 |
11.66 |
| 2026-04-04 12:00 |
21:36:03.04 |
+23:47:03.0 |
HIP 106630 |
11.10 |
| 2026-04-05 00:00 |
21:36:06.37 |
+23:47:45.7 |
HIP 106630 |
10.61 |
| 2026-04-05 12:00 |
21:36:09.66 |
+23:48:28.5 |
HIP 106630 |
10.20 |
| 2026-04-06 00:00 |
21:36:12.90 |
+23:49:11.5 |
HIP 106630 |
9.87 |
| 2026-04-06 12:00 |
21:36:16.11 |
+23:49:54.5 |
HIP 106630 |
9.64 |
| 2026-04-07 00:00 |
21:36:19.27 |
+23:50:37.8 |
HIP 106630 |
9.50 |
| 2026-04-07 12:00 |
21:36:22.38 |
+23:51:21.1 |
HIP 106630 |
9.46 |
| 2026-04-08 00:00 |
21:36:25.45 |
+23:52:04.5 |
HIP 106630 |
9.52 |
| 2026-04-08 12:00 |
21:36:28.48 |
+23:52:48.1 |
HIP 106630 |
9.67 |
| 2026-04-09 00:00 |
21:36:31.46 |
+23:53:31.8 |
HIP 106630 |
9.92 |
| 2026-04-09 12:00 |
21:36:34.40 |
+23:54:15.6 |
HIP 106630 |
10.25 |
| 2026-04-10 00:00 |
21:36:37.30 |
+23:54:59.5 |
HIP 106630 |
10.64 |
| 2026-04-10 12:00 |
21:36:40.15 |
+23:55:43.5 |
HIP 106630 |
11.11 |
| 2026-04-11 00:00 |
21:36:42.95 |
+23:56:27.5 |
HIP 106630 |
11.62 |
| 2026-04-11 12:00 |
21:36:45.71 |
+23:57:11.7 |
HIP 106630 |
12.18 |
| 2026-04-12 00:00 |
21:36:48.42 |
+23:57:56.0 |
HIP 106630 |
12.78 |
| 2026-04-12 12:00 |
21:36:51.09 |
+23:58:40.4 |
HIP 106630 |
13.41 |
| 2026-04-13 00:00 |
21:36:53.71 |
+23:59:24.8 |
HIP 106630 |
14.07 |
| 2026-04-13 12:00 |
21:36:56.28 |
+24:00:09.3 |
HIP 106630 |
14.75 |
| 2026-04-14 00:00 |
21:36:58.81 |
+24:00:53.9 |
HIP 106630 |
15.45 |
| 2026-04-14 12:00 |
21:37:01.29 |
+24:01:38.5 |
HIP 106630 |
16.16 |
| 2026-04-15 00:00 |
21:37:03.72 |
+24:02:23.3 |
HIP 106630 |
16.88 |
| 2026-04-15 12:00 |
21:37:06.10 |
+24:03:08.0 |
HIP 106630 |
17.62 |
| 2026-04-16 00:00 |
21:37:08.44 |
+24:03:52.9 |
HIP 106630 |
18.35 |