| Parameter |
Value |
| Designation |
C/2015 H2 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2016-09-13T06:35:06.138240Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:09Z |
| Obs used |
204 |
| NEO |
- |
| M1 |
11.300 |
| K1 |
5.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-02-24.0000000 |
| e |
1.00351211 |
| q (au) |
4.967122 |
| a (au) |
-1414.285460 |
| i (deg) |
33.705314 |
| Ω (om, deg) |
350.691893 |
| ω (w, deg) |
287.907632 |
| M (ma, deg) |
0.003034 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.727 + 2.871\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.727 |
| n |
2.871 |
| gf |
1.000 |
| gb |
-0.966 |
| 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 |
| 2014-05-19 |
2016-09-08 |
+5.0679 |
-3.734 |
| 2016-11-03 |
2018-08-10 |
+6.2905 |
-4.906 |
| 2018-08-10 |
2019-10-22 |
-4.7741 |
+4.167 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
01:43:09.03 |
+39:17:07.1 |
HIP 7951 |
14.08 |
| 2026-09-20 12:00 |
01:43:03.98 |
+39:17:12.1 |
HIP 7951 |
13.22 |
| 2026-09-21 00:00 |
01:42:58.91 |
+39:17:16.6 |
HIP 7951 |
12.38 |
| 2026-09-21 12:00 |
01:42:53.81 |
+39:17:20.7 |
HIP 7951 |
11.56 |
| 2026-09-22 00:00 |
01:42:48.68 |
+39:17:24.5 |
HIP 7951 |
10.78 |
| 2026-09-22 12:00 |
01:42:43.53 |
+39:17:27.7 |
HIP 7951 |
10.03 |
| 2026-09-23 00:00 |
01:42:38.34 |
+39:17:30.6 |
HIP 7951 |
9.33 |
| 2026-09-23 12:00 |
01:42:33.13 |
+39:17:33.1 |
HIP 7951 |
8.69 |
| 2026-09-24 00:00 |
01:42:27.89 |
+39:17:35.2 |
HIP 7951 |
8.13 |
| 2026-09-24 12:00 |
01:42:22.62 |
+39:17:36.8 |
HIP 7951 |
7.67 |
| 2026-09-25 00:00 |
01:42:17.32 |
+39:17:38.0 |
HIP 7951 |
7.33 |
| 2026-09-25 12:00 |
01:42:12.01 |
+39:17:38.9 |
HIP 7951 |
7.13 |
| 2026-09-26 00:00 |
01:42:06.66 |
+39:17:39.3 |
HIP 7951 |
7.08 |
| 2026-09-26 12:00 |
01:42:01.29 |
+39:17:39.3 |
HIP 7951 |
7.19 |
| 2026-09-27 00:00 |
01:41:55.90 |
+39:17:38.8 |
HIP 7951 |
7.45 |
| 2026-09-27 12:00 |
01:41:50.48 |
+39:17:38.0 |
HIP 7951 |
7.85 |
| 2026-09-28 00:00 |
01:41:45.04 |
+39:17:36.8 |
HIP 7951 |
8.37 |
| 2026-09-28 12:00 |
01:41:39.58 |
+39:17:35.1 |
HIP 7951 |
8.99 |
| 2026-09-29 00:00 |
01:41:34.09 |
+39:17:33.0 |
HIP 7951 |
9.70 |
| 2026-09-29 12:00 |
01:41:28.59 |
+39:17:30.6 |
HIP 7951 |
10.47 |
| 2026-09-30 00:00 |
01:41:23.06 |
+39:17:27.7 |
HIP 7951 |
11.30 |
| 2026-09-30 12:00 |
01:41:17.51 |
+39:17:24.3 |
HIP 7951 |
12.17 |
| 2026-10-01 00:00 |
01:41:11.94 |
+39:17:20.6 |
HIP 7923 |
13.04 |
| 2026-10-01 12:00 |
01:41:06.35 |
+39:17:16.5 |
HIP 7923 |
13.74 |
| 2026-10-02 00:00 |
01:41:00.74 |
+39:17:11.9 |
HIP 7923 |
14.49 |
| 2026-10-02 12:00 |
01:40:55.11 |
+39:17:07.0 |
HIP 7923 |
15.29 |
| 2026-10-03 00:00 |
01:40:49.46 |
+39:17:01.6 |
HIP 7923 |
16.13 |
| 2026-10-03 12:00 |
01:40:43.79 |
+39:16:55.8 |
HIP 7923 |
17.01 |
| 2026-10-04 00:00 |
01:40:38.11 |
+39:16:49.6 |
HIP 7923 |
17.92 |
| 2026-10-04 12:00 |
01:40:32.41 |
+39:16:43.0 |
HIP 7793 |
18.78 |
| 2026-10-05 00:00 |
01:40:26.70 |
+39:16:36.0 |
HIP 7793 |
18.76 |
| 2026-10-05 12:00 |
01:40:20.96 |
+39:16:28.6 |
HIP 7773 |
18.61 |
| 2026-10-06 00:00 |
01:40:15.21 |
+39:16:20.8 |
HIP 7773 |
18.31 |
| 2026-10-06 12:00 |
01:40:09.45 |
+39:16:12.5 |
HIP 7773 |
18.07 |
| 2026-10-07 00:00 |
01:40:03.67 |
+39:16:03.9 |
HIP 7773 |
17.89 |
| 2026-10-07 12:00 |
01:39:57.88 |
+39:15:54.8 |
HIP 7773 |
17.77 |
| 2026-10-08 00:00 |
01:39:52.08 |
+39:15:45.4 |
HIP 7773 |
17.72 |
| 2026-10-08 12:00 |
01:39:46.26 |
+39:15:35.5 |
HIP 7631 |
17.66 |
| 2026-10-09 00:00 |
01:39:40.44 |
+39:15:25.3 |
HIP 7631 |
16.66 |
| 2026-10-09 12:00 |
01:39:34.60 |
+39:15:14.6 |
HIP 7631 |
15.68 |
| 2026-10-10 00:00 |
01:39:28.75 |
+39:15:03.5 |
HIP 7631 |
14.72 |
| 2026-10-10 12:00 |
01:39:22.89 |
+39:14:52.1 |
HIP 7631 |
13.79 |
| 2026-10-11 00:00 |
01:39:17.01 |
+39:14:40.2 |
HIP 7631 |
12.89 |