| 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) |
| 2026-06-01 00:00 |
01:42:50.19 |
+37:00:03.0 |
HIP 8072 |
11.62 |
| 2026-06-01 12:00 |
01:42:55.29 |
+37:00:52.8 |
HIP 8072 |
10.35 |
| 2026-06-02 00:00 |
01:43:00.36 |
+37:01:42.8 |
HIP 8072 |
9.11 |
| 2026-06-02 12:00 |
01:43:05.39 |
+37:02:32.8 |
HIP 8072 |
7.88 |
| 2026-06-03 00:00 |
01:43:10.40 |
+37:03:22.8 |
HIP 8072 |
6.70 |
| 2026-06-03 12:00 |
01:43:15.37 |
+37:04:12.9 |
HIP 8072 |
5.57 |
| 2026-06-04 00:00 |
01:43:20.30 |
+37:05:03.1 |
HIP 8072 |
4.55 |
| 2026-06-04 12:00 |
01:43:25.21 |
+37:05:53.3 |
HIP 8072 |
3.70 |
| 2026-06-05 00:00 |
01:43:30.07 |
+37:06:43.6 |
HIP 8072 |
3.17 |
| 2026-06-05 12:00 |
01:43:34.91 |
+37:07:33.9 |
HIP 8072 |
3.12 |
| 2026-06-06 00:00 |
01:43:39.71 |
+37:08:24.3 |
HIP 8072 |
3.56 |
| 2026-06-06 12:00 |
01:43:44.48 |
+37:09:14.7 |
HIP 8072 |
4.35 |
| 2026-06-07 00:00 |
01:43:49.21 |
+37:10:05.2 |
HIP 8072 |
5.32 |
| 2026-06-07 12:00 |
01:43:53.91 |
+37:10:55.7 |
HIP 8072 |
6.40 |
| 2026-06-08 00:00 |
01:43:58.57 |
+37:11:46.2 |
HIP 8072 |
7.52 |
| 2026-06-08 12:00 |
01:44:03.19 |
+37:12:36.8 |
HIP 8072 |
8.69 |
| 2026-06-09 00:00 |
01:44:07.78 |
+37:13:27.4 |
HIP 8072 |
9.86 |
| 2026-06-09 12:00 |
01:44:12.33 |
+37:14:18.1 |
HIP 8072 |
11.05 |
| 2026-06-10 00:00 |
01:44:16.85 |
+37:15:08.7 |
HIP 8072 |
12.25 |
| 2026-06-10 12:00 |
01:44:21.33 |
+37:15:59.4 |
HIP 8072 |
13.45 |
| 2026-06-11 00:00 |
01:44:25.77 |
+37:16:50.2 |
HIP 8072 |
14.65 |
| 2026-06-11 12:00 |
01:44:30.17 |
+37:17:40.9 |
HIP 8072 |
15.85 |
| 2026-06-12 00:00 |
01:44:34.54 |
+37:18:31.7 |
HIP 8072 |
17.04 |
| 2026-06-12 12:00 |
01:44:38.86 |
+37:19:22.4 |
HIP 8072 |
18.24 |
| 2026-06-13 00:00 |
01:44:43.15 |
+37:20:13.2 |
HIP 8072 |
19.43 |
| 2026-06-13 12:00 |
01:44:47.40 |
+37:21:04.0 |
HIP 8123 |
19.64 |
| 2026-06-14 00:00 |
01:44:51.61 |
+37:21:54.8 |
HIP 8123 |
19.05 |
| 2026-06-14 12:00 |
01:44:55.78 |
+37:22:45.6 |
HIP 8123 |
18.51 |
| 2026-06-15 00:00 |
01:44:59.92 |
+37:23:36.4 |
HIP 8123 |
18.03 |
| 2026-06-15 12:00 |
01:45:04.01 |
+37:24:27.3 |
HIP 8123 |
17.62 |
| 2026-06-16 00:00 |
01:45:08.06 |
+37:25:18.1 |
HIP 8123 |
17.27 |
| 2026-06-16 12:00 |
01:45:12.07 |
+37:26:08.9 |
HIP 8123 |
16.99 |
| 2026-06-17 00:00 |
01:45:16.04 |
+37:26:59.7 |
HIP 8123 |
16.78 |
| 2026-06-17 12:00 |
01:45:19.97 |
+37:27:50.4 |
HIP 8123 |
16.65 |
| 2026-06-18 00:00 |
01:45:23.86 |
+37:28:41.2 |
HIP 8123 |
16.58 |
| 2026-06-18 12:00 |
01:45:27.70 |
+37:29:32.0 |
HIP 8123 |
16.59 |
| 2026-06-19 00:00 |
01:45:31.51 |
+37:30:22.7 |
HIP 8123 |
16.67 |
| 2026-06-19 12:00 |
01:45:35.27 |
+37:31:13.4 |
HIP 8123 |
16.82 |
| 2026-06-20 00:00 |
01:45:38.99 |
+37:32:04.1 |
HIP 8123 |
17.03 |
| 2026-06-20 12:00 |
01:45:42.67 |
+37:32:54.8 |
HIP 8123 |
17.31 |
| 2026-06-21 00:00 |
01:45:46.30 |
+37:33:45.4 |
HIP 8123 |
17.65 |
| 2026-06-21 12:00 |
01:45:49.89 |
+37:34:36.0 |
HIP 8123 |
18.04 |
| 2026-06-22 00:00 |
01:45:53.44 |
+37:35:26.6 |
HIP 8123 |
18.47 |