| 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
$$
M_a = (10.029 + 2.136\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.029 |
| n |
2.136 |
| gf |
0.974 |
| gb |
-0.500 |
| k |
1.000 |
| δ90 |
9.982 |
| 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 |
+6.5323 |
-4.790 |
| 2016-11-03 |
2019-10-22 |
+0.0641 |
-0.234 |
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 |
01:39:03.16 |
+36:28:06.5 |
HIP 7700 |
4.59 |
| 2026-05-12 12:00 |
01:39:09.30 |
+36:28:52.0 |
HIP 7700 |
3.75 |
| 2026-05-13 00:00 |
01:39:15.42 |
+36:29:37.6 |
HIP 7700 |
3.35 |
| 2026-05-13 12:00 |
01:39:21.52 |
+36:30:23.3 |
HIP 7700 |
3.55 |
| 2026-05-14 00:00 |
01:39:27.61 |
+36:31:09.2 |
HIP 7700 |
4.25 |
| 2026-05-14 12:00 |
01:39:33.67 |
+36:31:55.3 |
HIP 7700 |
5.25 |
| 2026-05-15 00:00 |
01:39:39.71 |
+36:32:41.5 |
HIP 7700 |
6.42 |
| 2026-05-15 12:00 |
01:39:45.73 |
+36:33:27.8 |
HIP 7700 |
7.68 |
| 2026-05-16 00:00 |
01:39:51.73 |
+36:34:14.3 |
HIP 7728 |
8.70 |
| 2026-05-16 12:00 |
01:39:57.70 |
+36:35:01.0 |
HIP 7728 |
8.74 |
| 2026-05-17 00:00 |
01:40:03.65 |
+36:35:47.7 |
HIP 7728 |
9.00 |
| 2026-05-17 12:00 |
01:40:09.58 |
+36:36:34.6 |
HIP 7728 |
9.47 |
| 2026-05-18 00:00 |
01:40:15.49 |
+36:37:21.7 |
HIP 7728 |
10.11 |
| 2026-05-18 12:00 |
01:40:21.38 |
+36:38:08.8 |
HIP 7728 |
10.89 |
| 2026-05-19 00:00 |
01:40:27.24 |
+36:38:56.1 |
HIP 7728 |
11.79 |
| 2026-05-19 12:00 |
01:40:33.07 |
+36:39:43.6 |
HIP 7728 |
12.77 |
| 2026-05-20 00:00 |
01:40:38.88 |
+36:40:31.1 |
HIP 7903 |
13.63 |
| 2026-05-20 12:00 |
01:40:44.67 |
+36:41:18.8 |
HIP 7903 |
13.10 |
| 2026-05-21 00:00 |
01:40:50.43 |
+36:42:06.5 |
HIP 7903 |
12.70 |
| 2026-05-21 12:00 |
01:40:56.17 |
+36:42:54.4 |
HIP 7903 |
12.46 |
| 2026-05-22 00:00 |
01:41:01.88 |
+36:43:42.4 |
HIP 7903 |
12.38 |
| 2026-05-22 12:00 |
01:41:07.56 |
+36:44:30.6 |
HIP 7903 |
12.46 |
| 2026-05-23 00:00 |
01:41:13.22 |
+36:45:18.8 |
HIP 7903 |
12.70 |
| 2026-05-23 12:00 |
01:41:18.85 |
+36:46:07.1 |
HIP 7903 |
13.09 |
| 2026-05-24 00:00 |
01:41:24.45 |
+36:46:55.6 |
HIP 7903 |
13.60 |
| 2026-05-24 12:00 |
01:41:30.03 |
+36:47:44.1 |
HIP 7903 |
14.24 |
| 2026-05-25 00:00 |
01:41:35.57 |
+36:48:32.8 |
HIP 7903 |
14.98 |
| 2026-05-25 12:00 |
01:41:41.09 |
+36:49:21.5 |
HIP 7903 |
15.81 |
| 2026-05-26 00:00 |
01:41:46.59 |
+36:50:10.3 |
HIP 7903 |
16.71 |
| 2026-05-26 12:00 |
01:41:52.05 |
+36:50:59.3 |
HIP 7903 |
17.67 |
| 2026-05-27 00:00 |
01:41:57.48 |
+36:51:48.3 |
HIP 7903 |
18.68 |
| 2026-05-27 12:00 |
01:42:02.89 |
+36:52:37.4 |
HIP 7903 |
19.73 |
| 2026-05-28 00:00 |
01:42:08.27 |
+36:53:26.6 |
HIP 7903 |
20.82 |
| 2026-05-28 12:00 |
01:42:13.61 |
+36:54:15.8 |
HIP 8072 |
20.80 |
| 2026-05-29 00:00 |
01:42:18.93 |
+36:55:05.2 |
HIP 8072 |
19.46 |
| 2026-05-29 12:00 |
01:42:24.22 |
+36:55:54.6 |
HIP 8072 |
18.14 |
| 2026-05-30 00:00 |
01:42:29.47 |
+36:56:44.2 |
HIP 8072 |
16.82 |
| 2026-05-30 12:00 |
01:42:34.70 |
+36:57:33.7 |
HIP 8072 |
15.50 |
| 2026-05-31 00:00 |
01:42:39.89 |
+36:58:23.4 |
HIP 8072 |
14.20 |
| 2026-05-31 12:00 |
01:42:45.06 |
+36:59:13.1 |
HIP 8072 |
12.90 |
| 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 |